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ECON 20110 Fall 2013 - Lecture 13: Redistribution — Transcript

by Glen Weyl · 10,611 words · 1,558 segments · language en · Watch on YouTube

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  1. 0:01okay let's get started so
  2. 0:05um today we're going to apply Monopoly
  3. 0:08Theory to I think a very important
  4. 0:10social problem which is the growing
  5. 0:13inequality uh in the United States uh um
  6. 0:17as well as many other countries and I'm
  7. 0:19going to talk about why one might be
  8. 0:21concerned about this um even from sort
  9. 0:25of a Libertarian perspective why
  10. 0:27redistribution might be valuable because
  11. 0:30it provides insurance against risks that
  12. 0:33people would have chosen to insure
  13. 0:35themselves against if they had the
  14. 0:36opportunity to do so but that they don't
  15. 0:38have the opportunity to
  16. 0:40do um and I'll talk about from that
  17. 0:43perspective what
  18. 0:45optimal Insurance should try to do
  19. 0:48maximizing people's expected
  20. 0:50utilities and that uh concave utility as
  21. 0:54a function of wealth means that the poor
  22. 0:57value a marginal dollar more than the
  23. 0:58rich do and therefore that
  24. 1:00redistribution is valuable and we'll
  25. 1:02talk about logarithmic utility as a good
  26. 1:04approximation to this we'll then build a
  27. 1:06framework for analyzing optimal
  28. 1:09Taxation and we'll analyze two things in
  29. 1:12that context first uh the optimal linear
  30. 1:16or sort of average tax rate that people
  31. 1:18pay so you know in reality tax schedules
  32. 1:21are like you know you pay a certain rate
  33. 1:23on the first certain amount of income
  34. 1:25more on the next certain amount etc
  35. 1:28etc um but you can think of the optimal
  36. 1:31linear tax as a measure of um sort of
  37. 1:35what the average tax rate should be and
  38. 1:37we'll calibrate that using a log
  39. 1:40logistic distribution of income which is
  40. 1:42a reasonably good fit to the US income
  41. 1:44distribution then we'll also talk about
  42. 1:46the optimal special sear charge for the
  43. 1:48rich so I don't know if you guys
  44. 1:50remember but a few years ago Obama was
  45. 1:52talking about introducing an extra tax
  46. 1:54on people earning over a million dollar
  47. 1:56and we'll talk about uh what what that
  48. 1:58should be and we'll calibrate that using
  49. 2:01the fact that at the top end of the
  50. 2:02income Spectrum the distribution of
  51. 2:04incomes is roughly
  52. 2:06Paro um like those fat tail
  53. 2:08distributions we talked about and then
  54. 2:10we'll talk about evidence on labor
  55. 2:12Supply elasticity which is the other key
  56. 2:14parameter other than inequality in
  57. 2:17determining optimal
  58. 2:18redistribution and then finally I'll
  59. 2:20talk a little bit about an alternative
  60. 2:22theory of optimal income taxation that
  61. 2:25um that I've been developing with some
  62. 2:28co-authors recently okay so income
  63. 2:31inequality uh can be measured in roughly
  64. 2:35three broad types of ways one is income
  65. 2:38inequality at the very bottom of the
  66. 2:39distribution the second is income
  67. 2:41inequality throughout the main part of
  68. 2:42the distribution and the third is at the
  69. 2:44very top so poverty me measures
  70. 2:47inequality at the very bottom and this
  71. 2:49is typically measured by the fraction of
  72. 2:50individuals who are below some line um
  73. 2:54so there's a global poverty line of $1
  74. 2:57per day but uh that's not really a
  75. 3:01reasonable or useful measure in the
  76. 3:02United States where people are so much
  77. 3:04richer so in the United States there's
  78. 3:06also sort of a relative poverty line
  79. 3:08which measures this inequality at the
  80. 3:10bottom and the interesting thing is
  81. 3:12despite the fact that we'll talk about
  82. 3:14um how inequality is been growing uh
  83. 3:17poverty in the United States has not
  84. 3:19been growing in fact it's been declining
  85. 3:22so uh inequality at the bottom end of
  86. 3:24the spectrum has not been grown on the
  87. 3:26other hand inequality in the mid-range
  88. 3:29is usually measured by the Genny
  89. 3:31coefficient which is a measure of how
  90. 3:34far from perfect equality the economy is
  91. 3:36and let me just show you what that looks
  92. 3:38like so um this curve here is called the
  93. 3:43Loren curve this says if we consider the
  94. 3:46bottom say 50% of people in the
  95. 3:49population what fraction of all of the
  96. 3:52income do they earn if there was perfect
  97. 3:54equality that would be 50% right then
  98. 3:57you can get you know at the bottom 7 %
  99. 4:00what fraction do they earn Etc that
  100. 4:02draws out this thing called Loren curve
  101. 4:04and then the geny coefficient is the
  102. 4:07area above the Loren's curve and below
  103. 4:09the line of perfect equality divided by
  104. 4:12the total area of this
  105. 4:15triangle yep has there been any Research
  106. 4:17into what is the optimal level of
  107. 4:21inequality on any kind of meure uh yeah
  108. 4:24there's a ton of stuff about that um
  109. 4:26there's a whole literature on whether
  110. 4:28inequality or to what extent inequality
  111. 4:30might increase or decrease growth one
  112. 4:33way of thinking about that is exactly
  113. 4:34what we're going to study today which is
  114. 4:37how much redistribution should you do
  115. 4:40but you know the question when you say
  116. 4:42optimal is optimal with respect to what
  117. 4:44intervention you know what I mean
  118. 4:46because like how would one change
  119. 4:48inequality well one way you could do it
  120. 4:50is by taxing and redistributing another
  121. 4:53way you could do it is by killing off
  122. 4:56all the poor
  123. 4:57people another way you could do it is by
  124. 5:00not killing off all the poor people but
  125. 5:01stopping any poor people from having
  126. 5:03children so I mean there are many
  127. 5:05different interventions and to really
  128. 5:07talk about the optimal extent of
  129. 5:09inequality you need to say optimal with
  130. 5:11respect to like what particular policy
  131. 5:13intervention that could change it so
  132. 5:15yeah I guess a related question is why
  133. 5:17is it that when they that um you're
  134. 5:21measuring this so when you do your gain
  135. 5:23coition it's with respect to perfect
  136. 5:24equality so why is it necessarily that
  137. 5:27as close to a some level of inequality
  138. 5:29well because it's just trying to measure
  139. 5:31how much inequality there
  140. 5:33is it's not attempting to say what it
  141. 5:37should be it's just measuring the degree
  142. 5:39of inequality so it's a it's a purely
  143. 5:41positive measure not a normative
  144. 5:45measure okay so
  145. 5:48um the the second uh the last measure is
  146. 5:54top income
  147. 5:56shares so this is what part of income
  148. 5:59does the do the richest people take so
  149. 6:03you might ask what fraction does the top
  150. 6:0410% take of all income top 1% and this
  151. 6:08measures inequality at the very uh high
  152. 6:11end of the spectrum as well so this has
  153. 6:14been growing radically in recent years
  154. 6:17in the United States and it's mostly at
  155. 6:19the very very top so this shows over the
  156. 6:22years what fraction of national income
  157. 6:25is acing to the top 1% the top 5 to 1%
  158. 6:30and the top 10 to 5% and as you'll
  159. 6:32notice there's been a little bit of
  160. 6:33increase in the top 5 to 1% hardly any
  161. 6:36increase in the top 10 to 5% and the top
  162. 6:391% has just
  163. 6:42skyrocketed but in other countries
  164. 6:46that's not uh true so if you look at the
  165. 6:49top 1%
  166. 6:51share in France it's come down and
  167. 6:54stayed down in Japan it's come down and
  168. 6:57stayed down Etc
  169. 7:02okay um
  170. 7:05and if you look at inequality at a a
  171. 7:08global
  172. 7:09scale the only part of it that's been
  173. 7:12increasing is the number of people that
  174. 7:14are super
  175. 7:16rich whereas overall geny coefficient
  176. 7:18has increased a little bit uh but not
  177. 7:21very much um especially not in recent
  178. 7:25years and um uh the fraction
  179. 7:30uh Super Rich that are coming from the
  180. 7:32United States is actually not increased
  181. 7:34because there come to be a lot more
  182. 7:36super rich people in other uh
  183. 7:38countries okay so many Libertarians and
  184. 7:43conservatives tend to oppose
  185. 7:45redistribution and I used to be uh one
  186. 7:48of these so I sort of emphathize with
  187. 7:50these ideas uh and let me go through
  188. 7:53what some of their standard arguments
  189. 7:55against redistribution are so one the
  190. 7:58most common one is that you know rich
  191. 7:59people earn their money so who has the
  192. 8:01right to take it away from them another
  193. 8:03argument that you hear a lot is social
  194. 8:05Darwinism which is that rich people are
  195. 8:08better than other people uh that's why
  196. 8:11they got rich and if we want the society
  197. 8:13to be healthy to work you know Etc we
  198. 8:15need to have more uh of them that could
  199. 8:18either mean that we want them to have
  200. 8:19more children and we think if they have
  201. 8:20more money they'll have more children it
  202. 8:22could also be that we think that they're
  203. 8:24better at using that money in a
  204. 8:26productive way poor people will just
  205. 8:27piss that money away or whatever the
  206. 8:29rich people use it for productive
  207. 8:32Investments another argument from Robert
  208. 8:36nosek uh is that um if they got their
  209. 8:41money in a fair way who has the right to
  210. 8:43take it away from them like if we
  211. 8:44started with an initially Fair situation
  212. 8:47and we enforced Fair rules along the way
  213. 8:49and some people got rich that well
  214. 8:51that's just the outcome of a bunch of
  215. 8:53fair things happening and so it couldn't
  216. 8:55be unfair another argument is that
  217. 9:00a Protestant argument is that the
  218. 9:02wealthy are wealthy because they were
  219. 9:04chosen by God and you know man should
  220. 9:06not undo what God
  221. 9:08chose Ein Rand argues that taxation is a
  222. 9:11form of violence and that property is
  223. 9:13basically inviable it's another standard
  224. 9:16libertarian perspective there are sort
  225. 9:19of fascistic arguments for uh against
  226. 9:22redistribution that basically
  227. 9:24redistribution encourages people to have
  228. 9:26conflicts between classes and that it's
  229. 9:28important to like Unity within a society
  230. 9:31and in order to do that uh we have to um
  231. 9:34avoid uh redistribution conservatives
  232. 9:38tend to argue that every like element of
  233. 9:41society has a role to play Within
  234. 9:43society and that redistribution can
  235. 9:45upset the ability of those traditional
  236. 9:48groups to play their relevant roles now
  237. 9:51um I think some of these arguments are
  238. 9:53quite interesting and powerful and I'm
  239. 9:55going to try to return a little bit to
  240. 9:57them later um
  241. 10:00and a lot of them haven't really been
  242. 10:01modeled that well by
  243. 10:03economists uh but I think that there's a
  244. 10:06pretty compelling argument even for a
  245. 10:09Libertarian for redistribution and in
  246. 10:11fact when I was a Libertarian it was
  247. 10:13this argument that originally persuaded
  248. 10:15me that redistribution might be
  249. 10:18desirable and it's very related to a
  250. 10:21classic Christian saying by John
  251. 10:24Bradford so he saw poor people being led
  252. 10:28through the streets uh to like a
  253. 10:30workhouse and he said there but for the
  254. 10:34grace of God go I and that is sort of
  255. 10:38the idea behind uh John
  256. 10:41haran uh and rs's argument for
  257. 10:44redistribution so you read the piece by
  258. 10:45John har this idea I've learned recently
  259. 10:48actually shows up even earlier in a
  260. 10:51paper by William vicory who won the
  261. 10:53Nobel prize in economics um and they
  262. 10:57gave sort of a Libertarian or
  263. 10:59choice-based approach to why we should
  264. 11:02have uh uh
  265. 11:05redistribution and can anyone tell me
  266. 11:08what what the basic idea of that is yeah
  267. 11:09Adam well um pretty much uh because
  268. 11:12people are too young in that situation
  269. 11:16to like make a decision about like
  270. 11:17insurance but because people are usually
  271. 11:20risk averse they would choose in that
  272. 11:22situation to lower their income in like
  273. 11:25the wealthy State and raise it in the
  274. 11:27poor State as a form of insurance so the
  275. 11:29government should do you do that
  276. 11:32redistribution because they obviously
  277. 11:34can't yeah so the idea is you know
  278. 11:36people almost always seek re uh
  279. 11:39insurance against bad things that might
  280. 11:41happen to them major risks in their life
  281. 11:43like medical insurance auto insurance
  282. 11:45Etc and the reason is because money is
  283. 11:47worth more to you when you have a lot of
  284. 11:49it than when you don't have as much of
  285. 11:51it and you know one of the biggest risks
  286. 11:54you face in life is what position you're
  287. 11:56going to end up in are you going to be a
  288. 11:57brilliant person who makes a lot of
  289. 11:59money money or you going to be a um poor
  290. 12:02person who makes a lot less money right
  291. 12:04which parents will you have will you
  292. 12:05have good parents or will you have
  293. 12:06crappy parents who don't take good care
  294. 12:09of you um what country or town are you
  295. 12:12born into Etc and people can't buy
  296. 12:15insurance against these things because
  297. 12:16they're too young or not even born yet
  298. 12:19and therefore the government should act
  299. 12:20as an insurance agent CH giving people
  300. 12:23the insurance that they would have
  301. 12:25chosen to get had they been able to
  302. 12:27choose to do so um and that's exactly
  303. 12:30what redistributive spending does so um
  304. 12:34this Advocates the idea that we should
  305. 12:36implement the policy that people would
  306. 12:38have chosen behind the veil of ignorance
  307. 12:40about who they are within
  308. 12:43Society um another way of putting it is
  309. 12:47Adam Smith so rather than the veil of
  310. 12:50ignorance he said imagine you were an
  311. 12:51impartial Outsider looking at people
  312. 12:54what would you think of as the
  313. 12:57distribution that you would you would
  314. 12:58choose yeah can so on about the John R
  315. 13:01said about this the here whole thing of
  316. 13:04the max Min principle which is Rel
  317. 13:06that's an extreme version of this and I
  318. 13:09think it's not a very plausible version
  319. 13:10of this or very consistent with his own
  320. 13:13logic because behind the veil of
  321. 13:14ignorance why would people suddenly have
  322. 13:16this Max Min uh preference rather than
  323. 13:19the risk preferences we see them
  324. 13:21actually having in the world which are
  325. 13:23not completely maxmen yeah that's
  326. 13:25basically exactly what I was ask about
  327. 13:27why yeah so I I I'm not I don't find
  328. 13:29rs's version of this very compelling I
  329. 13:32find the vicory and harani versions much
  330. 13:34more compelling yeah my um would this uh
  331. 13:38leg justification have like in itself
  332. 13:40moral hazard problems well but the thing
  333. 13:43is we didn't say that that necessarily
  334. 13:45means that you should redistribute
  335. 13:48everything because there might be
  336. 13:50consequences if I redistribute that I'll
  337. 13:52work less hard that's the reason why we
  338. 13:54don't give perfect Insurance to people
  339. 13:56because we want to retain some incentive
  340. 13:58that theyy to avoid the bad events right
  341. 14:02the idea is we wouldn't just like
  342. 14:03perfectly yeah and that's what the rest
  343. 14:05of the class is going to be about is the
  344. 14:06tradeoff between Insurance versus
  345. 14:08incentives
  346. 14:10okay um yeah that's up people who are
  347. 14:14highly
  348. 14:15talented like before like even before
  349. 14:17the veil of even with the veil of
  350. 14:19ignorance and even um like before
  351. 14:22knowing their position in life if
  352. 14:23they're like inly talented say that
  353. 14:26there is well but maybe their talent you
  354. 14:28can step back to a step before they know
  355. 14:30what their talent is that's sort of the
  356. 14:32idea I mean I don't know if you think
  357. 14:34you can step back to such a state and in
  358. 14:36fact that's like a big debate uh whether
  359. 14:38like there are things which even behind
  360. 14:40the veil of ignorance you already know
  361. 14:41about yourself but you know because I
  362. 14:44mean in no way that's like the classic
  363. 14:46argument against fre distribution right
  364. 14:48because some people like some I don't
  365. 14:51necessarily believe this but some people
  366. 14:52believe you know people who are inly
  367. 14:54talented the called and so if they're
  368. 14:57yeah so I mean if you basically believe
  369. 14:58that there are certain things like that
  370. 15:00it's just that certain types of people
  371. 15:02have more than other types of people
  372. 15:04because like say even behind there's no
  373. 15:07situation in which they didn't know that
  374. 15:10Noble sess that they had right and in
  375. 15:12some sense that's like the Protestant
  376. 15:15idea as well right it's the idea that
  377. 15:16like certain people are sort of chosen
  378. 15:18by God to be more talented so if you
  379. 15:21believe that then you wouldn't want this
  380. 15:23and in fact you know I think a really
  381. 15:25interesting research program that hasn't
  382. 15:27really been worked out in economics is
  383. 15:30like what would optimal taxes be in a
  384. 15:32world where there's some properties that
  385. 15:34we don't want to redistribute and others
  386. 15:36that we do so like for example when when
  387. 15:39like there's a ugly person we don't
  388. 15:41usually say oh it's so unlucky for them
  389. 15:44that they were ugly right whereas when
  390. 15:46there's a beautiful person that gets hit
  391. 15:48by a car and now is ugly we say it was
  392. 15:50so unlucky that such a beautiful person
  393. 15:51ended up ugly right so people might
  394. 15:54approach these some things is more like
  395. 15:56about luck and some things more about
  396. 15:58what you Des erve or what you earned
  397. 16:00Yeah Austin not strictly do any like
  398. 16:03political science research into the
  399. 16:05decline of religion Europe trying to
  400. 16:06connect that to the rise of the
  401. 16:08distribution so I feel like that yes
  402. 16:10there definitely has been I don't know
  403. 16:11it that well but I could definitely
  404. 16:13direct you to somebody who would know it
  405. 16:14I have a friend who like knows the
  406. 16:15redistributive literature like better
  407. 16:17than anybody in political science so um
  408. 16:21yeah right um this is like still like
  409. 16:24ultimately like a philosophical sort of
  410. 16:26judgment right yeah I mean lots of
  411. 16:29things that we build our theories up
  412. 16:30from our philosophical
  413. 16:32judgments pretty much everything is
  414. 16:34because in the
  415. 16:36end you can only deductively bring
  416. 16:39things back to some fundamental
  417. 16:41principles that you just have to accept
  418. 16:42on faith
  419. 16:44so um okay so this perspective would say
  420. 16:48that we should try to maximize average
  421. 16:50utility and that's called
  422. 16:53utilitarianism uh Jeremy benam uh
  423. 16:56described it as trying to create the
  424. 16:57greatest good for the greatest number of
  425. 17:00people um and usually the way that we
  426. 17:03model this is that people have some
  427. 17:05utility that depend on income plus some
  428. 17:07value that they get from everything else
  429. 17:11like Leisure their identity enjoyable
  430. 17:13work
  431. 17:14etc so for utilitarian social welfare is
  432. 17:19the sum of all these individual welfares
  433. 17:22and people are waited equally because
  434. 17:24you don't know uh which individual
  435. 17:26you're going to be you're equally likely
  436. 17:27to be any of them so from this
  437. 17:29perspective inequality is just another
  438. 17:31form of inefficiency it's an
  439. 17:33inefficiency from the failure to provide
  440. 17:35Insurance um because the rich don't
  441. 17:37value money as much as the poor do and
  442. 17:40the reason is risk aversion and that's
  443. 17:42what we're going to go through now yeah
  444. 17:44Tanner in that equation what is the uh F
  445. 17:47of little i what does that function mean
  446. 17:48that's the number of people with that
  447. 17:51income I yeah EV should U should U of I
  448. 17:55plus v of X be in parentheses
  449. 18:00yeah yeah that's right I mean I yeah
  450. 18:04exactly uh yeah Adam um so in this
  451. 18:08equation like then um redistribution
  452. 18:11isn't solely like monetary based like
  453. 18:13someone finds work more enjoyable then
  454. 18:15they might have like we distribute less
  455. 18:17income to them they get utility from
  456. 18:20other areas
  457. 18:22or yeah so that's actually a really good
  458. 18:24question so um this is really assuming
  459. 18:27that everyone has the same utility
  460. 18:28function over
  461. 18:30income and if that's true then this is
  462. 18:32going to be the right formulation but
  463. 18:34we'll talk a little bit I think at the
  464. 18:35end of the class about a model where
  465. 18:37people could vary both in terms of how
  466. 18:40much they like
  467. 18:41money versus other things and how
  468. 18:45talented they are right and depending on
  469. 18:50whether you think you should
  470. 18:51redistribute that or how you should
  471. 18:52think you should redistribute that that
  472. 18:54could affect so a lot of people think
  473. 18:56that there's like a basic principle that
  474. 18:58we should redistribute differences in
  475. 19:00ability but we shouldn't redistribute
  476. 19:02the fact that like one person likes to
  477. 19:04work harder than another person does or
  478. 19:06like cares more about money than another
  479. 19:08person does so yeah Tanner doesn't this
  480. 19:11assume that utility is Cardinal not
  481. 19:13ordinal well but but I think that people
  482. 19:17view it that way because they have to
  483. 19:19make like when people buy insurance
  484. 19:21they're saying that money is worth more
  485. 19:23to them when they're poor than when
  486. 19:24they're rich right and if you want to
  487. 19:27say like what would be my value for
  488. 19:28being various different people in the
  489. 19:30world you have to have some Cardinal
  490. 19:32isation of your utility for that so like
  491. 19:35when you have when you think about
  492. 19:36Choice over uncertainty that creates
  493. 19:38that has to create a calization of
  494. 19:42utility okay so utility is assumed to be
  495. 19:45concave in income and the idea behind
  496. 19:48this is risk aversion roughly you start
  497. 19:51as you get more money running out of
  498. 19:53good uses of that money so like when
  499. 19:55you're poor money is great because it
  500. 19:57allows you to buy like a house that
  501. 19:58doesn't fall down and food that you need
  502. 20:01and health basic health care as you
  503. 20:02start get getting richer what do you do
  504. 20:04with all the money I guess you can have
  505. 20:05like you know Justin Bieber come and
  506. 20:07sing for your daughter whatever but it
  507. 20:10maybe that's not as valuable per dollar
  508. 20:12as the other things right
  509. 20:15um okay now if you don't believe in risk
  510. 20:18aversion uh let let me give you a little
  511. 20:21example that hopefully will persuade you
  512. 20:23uh to believe in risk aversion okay so
  513. 20:26imagine that we flip a coin
  514. 20:29um and you get $2 if it comes up heads
  515. 20:32and if it comes up sorry if it comes up
  516. 20:34tails and if it comes up heads you flip
  517. 20:36it again if if it comes up tails you get
  518. 20:39$4 and if it comes up heads you flip it
  519. 20:41again etc etc etc doubling each time
  520. 20:46right so uh Austin how much would you be
  521. 20:50willing to pay in order for me to offer
  522. 20:52you this bet if you flip a coin can you
  523. 20:55explain that here okay I flip a coin if
  524. 20:58it comes up tails you get $2 if it comes
  525. 21:00up heads you get to flip again if it
  526. 21:03comes up tails you get $4 if it comes up
  527. 21:05heads you flip it again if it comes up
  528. 21:08taals you get 16 $8 yeah Etc let's see
  529. 21:11here it would be the value would be the
  530. 21:14sum
  531. 21:16of 2 n * 1 2
  532. 21:21N so
  533. 21:24$2 is that the sum of hold on 2 to the n
  534. 21:281 what's the sum from I = 1 to Infinity
  535. 21:33of 2 the I * 1 2 the i 2
  536. 21:38I what is 2 the I over 1 * 1 over 2 the
  537. 21:44i 2 I over
  538. 21:472 yeah what's that one one so it's the
  539. 21:51sum of one + 1 + 1 + 1 + 1 + 1 + 1
  540. 21:56infinitely so how much would you you
  541. 21:59personally be willing to pay in order to
  542. 22:01get me to do
  543. 22:03this you know I feel like there's some
  544. 22:08Inc yeah maybe yeah what would you what
  545. 22:13would you be willing to pay for this
  546. 22:14I'll put in 100 bucks 100 bucks is
  547. 22:17anyone here willing to pay more than 100
  548. 22:19bucks raise your
  549. 22:21hand um uh is anyone here willing to pay
  550. 22:26more than 200 bucks more than than a
  551. 22:28th000 bucks more than 10,000 bucks no I
  552. 22:33didn't think so okay uh so clearly you
  553. 22:35guys are not okay how much would a risk
  554. 22:38neutral person be willing to pay for
  555. 22:40this uh yes so well like
  556. 22:44an expected the
  557. 22:47expected exactly is
  558. 22:50this what no sorry you going say I was
  559. 22:53just thinking this kind of reminds me of
  560. 22:54like a physics question where like
  561. 22:56theoretically the tales are infinite but
  562. 22:58just because of like quantization is
  563. 22:59practic it seems like you got a similar
  564. 23:02thing no but I mean I could give you
  565. 23:03things that like didn't literally sum to
  566. 23:05an infinite amount but sub to something
  567. 23:07enormous and you still wouldn't be
  568. 23:08willing to pay you know a very large
  569. 23:11amount for it yeah M so every time it it
  570. 23:15lands heads you get to flip again yeah
  571. 23:17so why wouldn't anybody pay $10,000 for
  572. 23:20this because you keep getting larger
  573. 23:21payouts and then you know that it's
  574. 23:23going to come up taals like infly many
  575. 23:25times right if you but you only get to
  576. 23:27do it once oh
  577. 23:29okay so yeah yeah re so I mean in this
  578. 23:34it's possible you flip it once and get
  579. 23:36once you paid $10,000 for it you flip at
  580. 23:38ones it lands tails and you get two both
  581. 23:41yeah okay so you could
  582. 23:43lose
  583. 23:489,000 okay so apparently you guys are
  584. 23:50not risk
  585. 23:51neutral right and it's hard to imagine
  586. 23:54any reasonable person paying all that
  587. 23:56much for this thing right and and so
  588. 23:58therefore it seems reasonable to think
  589. 24:01that people are risk averse so imagine
  590. 24:03that people had log
  591. 24:05utility you could just go through and
  592. 24:07compute how much people are willing to
  593. 24:09pay for this uh starting from zero they
  594. 24:12should be willing to pay the log of all
  595. 24:13these things which is rather than
  596. 24:16doubling it it's only adding a constant
  597. 24:18so it would die off exponentially and
  598. 24:21you would be willing to pay very little
  599. 24:22for this yeah uh doesn't it depend on
  600. 24:25how much income you're currently at
  601. 24:28depend
  602. 24:29it does yeah so the more income you're
  603. 24:31currently at the more you should be
  604. 24:32willing to pay for this for
  605. 24:35sure um yeah so uh like even a gambler
  606. 24:41or like somebody who's considered
  607. 24:45um risk loving yeah they wouldn't like
  608. 24:49CU they're not really risk loving over
  609. 24:51the full range that's the point right
  610. 24:53like they might be risk lugging for a
  611. 24:55little bit but they wouldn't really take
  612. 24:57this big of a risk you know so they're
  613. 25:00like Risk loving for certain levels
  614. 25:03maybe I don't even think they're really
  615. 25:04risk loving I think that they like they
  616. 25:06they just are over optimistic about
  617. 25:08their chances of winning I mean that's
  618. 25:09my basic view yeah Tanner I actually
  619. 25:12want a guy who trades through for J
  620. 25:14Morgan say that he would want to bet on
  621. 25:15Cor if he could like in his job well of
  622. 25:19course that's true because he's betting
  623. 25:21with the government's
  624. 25:22money person like he loves to gamble
  625. 25:25that's people do I don't believe it
  626. 25:27maybe it's because he's used to
  627. 25:28something with a much lower expect no I
  628. 25:31I think that he's saying that like with
  629. 25:32the company's money he would want to do
  630. 25:34that because then in the end like you
  631. 25:37know if if it loses a lot of money the
  632. 25:39worst thing that happens is he get fired
  633. 25:41and if he makes a lot of money he gets
  634. 25:4230% of that he was talking about this in
  635. 25:44conjunction with his like gambling habit
  636. 25:46so like his personal I think he would do
  637. 25:48it for both time both but I would
  638. 25:49certainly wouldn't do it for like this
  639. 25:52much you know no but for some for some
  640. 25:54measure he was risk buing yeah maybe
  641. 25:57yeah I don't isn't it possible to be
  642. 25:59like purely risk averse and be a gambler
  643. 26:02you just also derive like utility from
  644. 26:04like the adrenaline or whatever maybe
  645. 26:06yeah I mean I think that it's mostly
  646. 26:08that people like misestimate the chance
  647. 26:11that they are going to win or they trick
  648. 26:15themselves into the kingdom yeah okay so
  649. 26:20um risk
  650. 26:21aversion um alone uh therefore gives
  651. 26:25some motive for redistribution
  652. 26:28but the if we're more specific about the
  653. 26:30form of utility we can get a much more
  654. 26:32useful uh
  655. 26:34measure um and luckily there's some
  656. 26:37pretty powerful evidence about this the
  657. 26:39same way there was for Zip's law in
  658. 26:41partic in particular a lot of uh
  659. 26:44evidence points us to The View that
  660. 26:45people's utility is roughly logarithmic
  661. 26:47which is kind of amazing because this
  662. 26:49form for utility was first proposed in
  663. 26:51the 17th century and basically nothing
  664. 26:53we've done since then has convinced us
  665. 26:55that there's any better approximation to
  666. 26:57people's utility since then um and this
  667. 27:00is super intuitive to think about it
  668. 27:02basically says the value of a certain
  669. 27:04percentage increase in your income is
  670. 27:06constant no matter what income you're at
  671. 27:07so like d like someone is just as happy
  672. 27:10to move from $50,000 of income to
  673. 27:12100,000 as from 100,000 to2 200,000 as
  674. 27:15from 200,000 to 400,000 Etc it's
  675. 27:18mathematically very convenient and has a
  676. 27:20lot of empirical support so my favorite
  677. 27:23support for this comes from uh paper by
  678. 27:25uh Dan sax and co-authors and they
  679. 27:28studied subjective wellbeing measures
  680. 27:31these are when we run a survey and we
  681. 27:33ask people on a ladder of life from zero
  682. 27:36being like the worst life you can
  683. 27:38imagine living to 10 being the best life
  684. 27:40you can imagine living where would you
  685. 27:42put yourself and let's let H be the
  686. 27:45number that people report and I be the
  687. 27:47income that they earn yeah philli um
  688. 27:50don't if you survey someone with
  689. 27:52sufficiently high income uh might you
  690. 27:55have a problem fitting this to a log
  691. 27:57data because if it was log outa they
  692. 27:59would want to report above a 10 but they
  693. 28:02can't because it's yeah I mean I don't
  694. 28:04think that you in a random sample very
  695. 28:07often get such people that's true
  696. 28:09because like yeah there's not that many
  697. 28:13people who are 10 log points higher than
  698. 28:17like a average person in the
  699. 28:19population it's it has to be even more
  700. 28:21than 10 log points here because the
  701. 28:23coefficient turns out to be33 so they'd
  702. 28:26have to be 30 log points out
  703. 28:30so that's a
  704. 28:31lot uh let me figure out exactly what
  705. 28:34that
  706. 28:41is but still isn't that kind of like
  707. 28:44somewhat fla
  708. 28:46measurement well hold on one second let
  709. 28:48me just figure this out e to the 30
  710. 28:52times let's say that someone who's at
  711. 28:54one is at one right so
  712. 28:59yeah it can't even tell me what that is
  713. 29:00it's some like ungodly large number
  714. 29:03about 10 to the it's on the order of
  715. 29:05about 10
  716. 29:1015 because e is approximately theare of
  717. 29:1310 so it's something like that yeah
  718. 29:17that's like that's like trillions of
  719. 29:20trillions of dollars right
  720. 29:23so um okay 1.07 * 10 the
  721. 29:2913 what's 10 the 13th so we take three
  722. 29:31off of that to get thousand three off of
  723. 29:33that nine off of that gets us to
  724. 29:36billions right take another three off
  725. 29:39that gets us to trillions so that's like
  726. 29:42hund tens or hundreds of trillions of
  727. 29:44dollars or something so yeah you're not
  728. 29:45going to get someone like that in exle
  729. 29:48okay uh so this is what they find fits
  730. 29:51incredibly well so this if you run this
  731. 29:55regression you get H is equal to35 * the
  732. 29:58log of income plus Epsilon so just to
  733. 30:00show you how powerful this is here are
  734. 30:03200 countries and each one of these
  735. 30:05countries they ran the regression within
  736. 30:07the country of income and here are the
  737. 30:10regression coefficients like given by
  738. 30:13these lines
  739. 30:14right and here is the cross country
  740. 30:16regression so you see these things are
  741. 30:18like all pretty much the same and
  742. 30:20they're all pretty much parallel to the
  743. 30:21cross country relationship so I think
  744. 30:24that shows pretty compelling evidence
  745. 30:26that um BAS basically logiic income does
  746. 30:30a good job of explaining uh yeah right
  747. 30:33but um doesn't like sort of measure of
  748. 30:37your wellbeing like run the same
  749. 30:39problems like a con valuation surve you
  750. 30:41would think so wouldn't
  751. 30:44you but I think the data speaks louder
  752. 30:47than the theory I mean like the fact
  753. 30:50that people that this does such a good
  754. 30:53job explaining the data I think answers
  755. 30:56a lot of the objections that you could
  756. 30:58happen too but what if like everybody
  757. 31:00has the same sort of bies like but then
  758. 31:03why does it line up so perfectly with
  759. 31:05the logarithm of their
  760. 31:11income I mean it's just like you know
  761. 31:13yeah I agree there th This Is Right
  762. 31:15without having any right to be right but
  763. 31:17still it is seems to be right yeah
  764. 31:20Austin what about like relative income
  765. 31:22effects exactly that's what you would
  766. 31:23think if it was relative income effects
  767. 31:25then you would expect the relationship
  768. 31:27cross countries to be much flatter than
  769. 31:28the Rel relationship within countries
  770. 31:31because the rich countries would
  771. 31:32everyone would have a higher Baseline
  772. 31:34and you wouldn't expect them to be any
  773. 31:35happier but that's not what
  774. 31:38happens yeah um is there any data on
  775. 31:42risk preferences that also support yes
  776. 31:45there's like a ton of data there's a
  777. 31:47nice paper by Raj cheddy that looks at
  778. 31:49like 10 different ways of measuring risk
  779. 31:51aversion they all line up really well
  780. 31:52with logarithmic
  781. 31:55utility okay so all the things together
  782. 31:58mean that I think especially given that
  783. 32:00it's so convenient we can just go run
  784. 32:02with logarithmic utility okay so
  785. 32:05designing an optimal tax system involves
  786. 32:07a wide range of issues you have to
  787. 32:09decide what you're going to tax is it
  788. 32:10going to be income consumption Capital
  789. 32:13how is the um how do we redistribute the
  790. 32:16money that's
  791. 32:17collected um what deductions do we give
  792. 32:21people and what is the base for the
  793. 32:23taxes uh do we give just uniform
  794. 32:26deductions or do we give them targeted
  795. 32:28to particular groups for doing
  796. 32:29particular things do we have inheritance
  797. 32:32taxes you know how do we tax different
  798. 32:34Generations how many brackets do we have
  799. 32:38and where at what income thresholds what
  800. 32:40rate do we have over each of these
  801. 32:42brackets we have to make decisions about
  802. 32:44the administrative process what
  803. 32:46government programs to spend the money
  804. 32:48on to give subsidies maybe over some
  805. 32:51range just for people getting into the
  806. 32:53workforce at all so these are really
  807. 32:55important issues but today we're only
  808. 32:57going to focus on two of them that have
  809. 32:59been sort of very important to economics
  810. 33:01as well as in the news one is how high
  811. 33:05should overall tax rates be and how flat
  812. 33:08or Progressive should things be on the
  813. 33:10Super Rich should we have like a higher
  814. 33:12rate on the Super Rich than on the rest
  815. 33:13of the population or not okay
  816. 33:16so you know if we if the poor value uh
  817. 33:22money more than the rich do why should
  818. 33:24we not just redistribute everything
  819. 33:26until we have perfect to Quality can
  820. 33:29someone uh yeah Julian uh because then
  821. 33:32nobody would have any incentive to work
  822. 33:34CU they can do not work and then they're
  823. 33:36still the same amount of money exactly
  824. 33:38because if you tax people more they have
  825. 33:40less marginal incentive to work so in
  826. 33:42particular Beyond some point more taxes
  827. 33:44are counterproductive because you'll
  828. 33:46actually raise less total revenue and
  829. 33:48this is uh called the equity efficiency
  830. 33:50tradeoff or the insurance incentives
  831. 33:53trade-off and the basic goal in this
  832. 33:55problem is to maximize average utility
  833. 33:58given that we can only use let's say a
  834. 34:00simple instrument we have like a linear
  835. 34:03tax on everyone's income and then we
  836. 34:06redistribute that back to people and
  837. 34:08then maybe we have the search charge on
  838. 34:09the rich and that raising taxes causes
  839. 34:12less work because people substitute down
  840. 34:15to doing less work and all revenue is
  841. 34:17given back lump sum to everyone now to
  842. 34:20keep things simple we're going to ignore
  843. 34:22income effects because
  844. 34:25um a lot of reseearch has shown that
  845. 34:28those aren't all that important to
  846. 34:29determining this problem we can
  847. 34:31incorporate them of course but the
  848. 34:33formulas get a uh
  849. 34:36Messier uh and it doesn't make much of a
  850. 34:38difference right so in that case all the
  851. 34:40reduction comes from What's called the
  852. 34:41labor Supply
  853. 34:42elasticity which is the percent Fallen
  854. 34:45work when your wages Fall by a percent
  855. 34:48and let's say that people who are
  856. 34:50currently earning income I have an
  857. 34:53average labor Supply elasticity of
  858. 34:55Epsilon bar
  859. 34:58okay now people's income after we have
  860. 35:01taxes and transfers are going to be
  861. 35:04they'll get one minus the tax rate times
  862. 35:07their income plus the tax rate times the
  863. 35:09average income because we're going to
  864. 35:11redistribute that average income that we
  865. 35:13tax away back to people lump some okay
  866. 35:17so um the post tax wage that people earn
  867. 35:22is one minus the tax rate times their
  868. 35:24wage
  869. 35:25right and so if we raise taxes by uh one
  870. 35:31unit how much is that going to cause
  871. 35:35people's earnings to Fall by if they
  872. 35:37have an elasticity of Epsilon Tanner can
  873. 35:40you derive
  874. 35:42that Bo yeah
  875. 35:44sure so the remember that the labor
  876. 35:47Supply elasticity was the
  877. 35:50elasticity of um like how much your
  878. 35:54income changed when your wage Changed by
  879. 35:571%
  880. 35:59%
  881. 36:25yep the post test which is that so you
  882. 36:28want to find the change in that as the
  883. 36:30tax changes yes exactly no the change
  884. 36:33the change in the total amount of income
  885. 36:35you're going to earn we also have to do
  886. 36:37that yeah so we'll have to figure out
  887. 36:39how much this changes how much the
  888. 36:40elasticity Chang yeah and then the
  889. 36:41elasticity will do the rest for us okay
  890. 37:14[Applause]
  891. 37:22so tea only shows up once in there right
  892. 37:24yeah so I'm
  893. 37:34yeah that's it and then you need to
  894. 37:37multiply so to get that turn that into
  895. 37:39an elas uh to to okay so then the
  896. 37:44elasticity says uh if you take that
  897. 37:48number uh and you divide it by the
  898. 37:53current uh wage which is W * 1 -
  899. 37:59T then you can multiply it by the
  900. 38:05elasticity and and then yeah and that
  901. 38:09should give you um how
  902. 38:13much uh how much the income by what uh
  903. 38:18percentage the amount that people work
  904. 38:20changes so it's just this
  905. 38:25yeah exactly
  906. 38:31so when we raise um the income when we
  907. 38:36raise
  908. 38:37taxes they'll uh the amount that people
  909. 38:40work will fall by the labor Supply
  910. 38:42elasticity averaged at that income tax
  911. 38:45level times 1 minus uh the T divided by
  912. 38:491 minus the tax rate okay and this is
  913. 38:54the income weighted average elasticity
  914. 38:57of Labor
  915. 38:59Supply uh and imagine that there is a
  916. 39:02density of people over different incomes
  917. 39:05of f ofi so like that's the number of
  918. 39:07people earning a given income that's
  919. 39:08what we were talking about before again
  920. 39:11we're going to ignore income effects so
  921. 39:14then total welfare remember is going to
  922. 39:17be the integral over the incomes of the
  923. 39:20logarithm of the income right now each
  924. 39:24individual by the envelope theorem the
  925. 39:27the only cost to them of taxing them is
  926. 39:30the amount of money that they
  927. 39:32lose times whatever their marginal
  928. 39:34valuation of that money is because any
  929. 39:37amount that they go into working uh into
  930. 39:41reducing the amount of work right
  931. 39:43they're choosing the optimal amount of
  932. 39:45work given um given uh the tax rate
  933. 39:49right so we can now take the derivative
  934. 39:52of this and what do we
  935. 39:55get well uh derivative of the logarithm
  936. 39:59is one over the inside right times the
  937. 40:03number of people at that income and then
  938. 40:05what happens to uh what happens to my
  939. 40:09income by the envelope theorem I can
  940. 40:11hold fixed but the average income is
  941. 40:14going to change because people other
  942. 40:15people are going to work less when we
  943. 40:17tax more right and what's that going to
  944. 40:21change by well I'm going to raise this
  945. 40:24by one because I'm collecting more taxes
  946. 40:29and then I'm going to reduce it by um
  947. 40:35the amount of
  948. 40:36taxes times however much the income
  949. 40:39changes which is the elasticity Time 1
  950. 40:42minus the tax rate and then these people
  951. 40:45also lose directly by the envelope
  952. 40:47theorem their
  953. 40:51income and that gives us this formula
  954. 40:55here which is 1
  955. 40:59minus the tax rate times the
  956. 41:02elasticity ID 1us the tax rate times the
  957. 41:06average income and the average welfare
  958. 41:08weight that's one o this is the amount
  959. 41:11of like value that the person gets from
  960. 41:13an additional dollar that's one over
  961. 41:15their post tax
  962. 41:17income minus the average value of the
  963. 41:20product of income and the welfare weight
  964. 41:24right now I'm going to define a variable
  965. 41:28Sigma which is going to be the negative
  966. 41:31co-variance of income divided by average
  967. 41:34income with welfare weight divided by
  968. 41:36average welfare weight now why should
  969. 41:38this be a negative number well the
  970. 41:41Richer someone is the less they value an
  971. 41:43additional dollar and this is sort of a
  972. 41:45measure of
  973. 41:47inequality why because if everyone had
  974. 41:50the same income there would be no
  975. 41:51covariance there right the more
  976. 41:54covariance there is there the more
  977. 41:56inequality there
  978. 41:58right the more that people's income are
  979. 42:01moving around and therefore the more
  980. 42:03their welfare rates are moving around
  981. 42:04now obviously if we have higher taxes
  982. 42:07that's reducing inequality and leading
  983. 42:09to less variation in the welfare weights
  984. 42:10and therefore less Co negative
  985. 42:12co-variance with income yes you well can
  986. 42:15you explain why um you Define welfare
  987. 42:16weight as one over the because that's
  988. 42:19the marginal utility that someone gets
  989. 42:21from an additional unit of uh dollar and
  990. 42:24that's therefore the weight the society
  991. 42:25should place on them getting an addition
  992. 42:27so if everybody has the same log
  993. 42:29function then isn't the coherence always
  994. 42:31going to
  995. 42:33be the same um no because it depends on
  996. 42:36the degree of inequality right because
  997. 42:38the thing is that um if someone has
  998. 42:40higher income then their weight is going
  999. 42:42to be lower because they value income
  1000. 42:45they value money less right and if you
  1001. 42:47make things more equal by having higher
  1002. 42:49tax rates then these are going to be
  1003. 42:50closer to being equal and there will be
  1004. 42:52less co-variance
  1005. 42:54there okay so
  1006. 43:00um optimization
  1007. 43:03then is going to
  1008. 43:05be that uh
  1009. 43:091us T average elasticity over 1 minus t
  1010. 43:13is equal to this
  1011. 43:16co-variance and so we can just solve out
  1012. 43:19that the optimal tax rate is going to be
  1013. 43:21equal to this measure of inequality
  1014. 43:24which depends on the tax rate divided by
  1015. 43:26the average elasticity times this
  1016. 43:28measure of inequality which depends on
  1017. 43:30the tax
  1018. 43:31rate okay so the tax is going to be
  1019. 43:37increasing in Sigma and decreasing in
  1020. 43:41epsilon and how does that uh capture the
  1021. 43:44trade-off between equity and efficiency
  1022. 43:46can someone explain that yeah joh this
  1023. 43:49it's increasing that means the equity is
  1024. 43:53increasing along the perance rate sorry
  1025. 43:56say that again it's becom more evitable
  1026. 43:58because the sigma is
  1027. 44:00increasing well so Sigma is a measure of
  1028. 44:03inequality right sorry so it's becom
  1029. 44:04more inequitable uhhuh so but okay so
  1030. 44:09what this is saying is that the more the
  1031. 44:11bigger Sigma is the bigger the optimal
  1032. 44:13tax rate should be and the bigger
  1033. 44:15Epsilon is the lower the optimal tax
  1034. 44:18rate should be so how does that reflect
  1035. 44:20this logic we were discussing before
  1036. 44:23that Julian was pointing out of the
  1037. 44:24trade-off between trying to get greater
  1038. 44:26equal quity and greater uh efficiency so
  1039. 44:31if Sigma is greater that means the tax
  1040. 44:34be greater at the same time that because
  1041. 44:36why why because why should it be greater
  1042. 44:40because well no I I agree but but why
  1043. 44:43why intuitively how does that correspond
  1044. 44:45to the intuitive logic we were talking
  1045. 44:46about before about the trade-off between
  1046. 44:48equality and
  1047. 44:52efficiency anybody else uh yep um bar uh
  1048. 44:59so uh as the elasticity increases the
  1049. 45:02tax rate should be lower because um if
  1050. 45:06the elasticity is higher that means
  1051. 45:08people are more responsive to a higher
  1052. 45:10tax rate will work less yes and
  1053. 45:12therefore there's more efficiency cost
  1054. 45:15because of the moral hazard issues right
  1055. 45:17yeah and and what about Sigma why when
  1056. 45:19that's higher should there be higher T
  1057. 45:22um because in that case if Sig higher is
  1058. 45:25more inquality yeah so a higher tax is
  1059. 45:28necessary
  1060. 45:29to distribute that because poor value
  1061. 45:32exactly
  1062. 45:35exactly
  1063. 45:37um okay so this is a simple
  1064. 45:39formalization of the equity efficiency
  1065. 45:41tradeoff and if Sigma is getting very
  1066. 45:44very large except near T equals 1 then
  1067. 45:48we're going to want tax rate of one or
  1068. 45:51if the elasticity goes to zero we're
  1069. 45:52going to want a tax rate of one and vice
  1070. 45:54versa so the more inequality there is
  1071. 45:57and the less elasticity is the higher
  1072. 45:59the optimal tax rate is okay so that
  1073. 46:03average tax rate covers um like the tax
  1074. 46:08that is going to be faced by most
  1075. 46:09Americans or most people in a given
  1076. 46:12country but Obama has now not that
  1077. 46:15recently caused uh called for a sear
  1078. 46:18charge on the super rich and when taxing
  1079. 46:23the super rich the amount of money that
  1080. 46:25they lose as a result of that tax
  1081. 46:27doesn't matter that much to see that
  1082. 46:29notice that um one over a million dollar
  1083. 46:34is only about 1 12th of one over the
  1084. 46:37median income in the United States and
  1085. 46:39so therefore like the marginal value of
  1086. 46:41an additional uh dollar for the rich
  1087. 46:44people is hardly anything compared to
  1088. 46:46for a typical person right and so a
  1089. 46:49simple way to think about this is that
  1090. 46:50we should just try to maximize revenues
  1091. 46:54um on on the wealthy right so imagine
  1092. 46:58that we had a tax rate for those earning
  1093. 47:01over a million dollar uh which we called
  1094. 47:05uh T sub 10 6 and let's let uh I bar sub
  1095. 47:1010 the 6 be the average income of those
  1096. 47:12who are earning over a million dollar
  1097. 47:15right now if we raise this tax rate
  1098. 47:18that's going to cause uh two effects can
  1099. 47:20someone describe to me what those two
  1100. 47:22effects will
  1101. 47:23be uh yeah um you're going to have a
  1102. 47:27higher a tax take mechanically cuz we
  1103. 47:31are raising uh we're taxing more heavily
  1104. 47:34but they are going to respond by working
  1105. 47:36less and that's going to have a opposite
  1106. 47:39effect exactly so there's a mechanical
  1107. 47:42increase in the revenue that we earn
  1108. 47:44which is that for every dollar that
  1109. 47:46these people earn over a million dollars
  1110. 47:48we'll get one more Dollar in tax revenue
  1111. 47:51but also there will be for everyone
  1112. 47:53earning an income Above This their
  1113. 47:55incomes will fall by this this amount
  1114. 47:57which will reduce the tax taxes that we
  1115. 47:59get by this amount yeah how is this so
  1116. 48:03when you say that increase revenue from
  1117. 48:05I by IUS 106 does that mean you're
  1118. 48:07taking every no it's only we don't get
  1119. 48:10money that's below a million these
  1120. 48:13people earn right because the tax ratees
  1121. 48:15only charged above a million do so it's
  1122. 48:18a marginal tax rate above a million doar
  1123. 48:20okay oh so you're just saying that we
  1124. 48:22get T * IUS well we get we're changing T
  1125. 48:26right so we get for every unit change in
  1126. 48:28t This Much from each
  1127. 48:30person yeah
  1128. 48:34re was what T der that's the percent
  1129. 48:37change yeah
  1130. 48:39exactly anybody
  1131. 48:42else okay so the total effect on revenue
  1132. 48:47is therefore we get i - 10 6 * 1 minus
  1133. 48:52this
  1134. 48:53reduction uh in in taxes is from the
  1135. 48:58effect we talked about and the optimal
  1136. 49:00tax is going to equate this to zero on
  1137. 49:02average for people above a million
  1138. 49:05dollar and this was the formula derived
  1139. 49:08by Emanuel Siz in 2001 so if we take
  1140. 49:11averages we just can put bars over all
  1141. 49:13this stuff right where again e bar sub
  1142. 49:1710 6 is the a average income weighted
  1143. 49:20elasticity of people earning an income
  1144. 49:22above uh a million dollar and I bar the
  1145. 49:266 again is the average income of those
  1146. 49:28who are earning over a
  1147. 49:30million okay so now let's define Alpha
  1148. 49:33to be I bar sub 10 6 divided I bar sub
  1149. 49:3810 6 minus 10 6 so that's the average
  1150. 49:41income that people earning above a
  1151. 49:42million are doing divided by on average
  1152. 49:45how much more than a million dollar are
  1153. 49:47they
  1154. 49:47earning okay so by the same logic as
  1155. 49:51before um what are we going to uh get as
  1156. 49:55the optimal tax formula Adam you could
  1157. 49:57you derive that on board yeah
  1158. 50:13sure so you'd set that equal to zero
  1159. 50:16yeah exactly and then try to use that
  1160. 50:19Alpha thing that
  1161. 50:20I find
  1162. 50:28o
  1163. 51:14C
  1164. 51:32[Applause]
  1165. 51:38[Applause]
  1166. 51:48yes so you've got to get all the t's on
  1167. 51:50one side so you can divide through and
  1168. 51:52solve for it right yeah so I just divide
  1169. 51:54by oh you've got another one on that
  1170. 51:57right so I actually don't think you did
  1171. 51:59a very good job isolating it there yeah
  1172. 52:02forgot about that too uh
  1173. 52:19so how about isolating the left hand
  1174. 52:22side
  1175. 52:23thing this over here yeah
  1176. 52:27and so subtracting one from subtract one
  1177. 52:29from both sides
  1178. 52:50yeah okay now before you do anything
  1179. 52:53else try turning the right hand side
  1180. 52:54into something that's related to
  1181. 52:55something I have on the
  1182. 52:57board
  1183. 52:59um
  1184. 53:01so this
  1185. 53:20equals so that would be one over Alpha
  1186. 53:23good okay so try putting that in that's
  1187. 53:25going to make your life easier
  1188. 53:43um now you need to isolate T sub 10 6
  1189. 53:59multiply both sides by the denominator
  1190. 54:01right
  1191. 54:17yeah okay
  1192. 54:32+ one
  1193. 54:36yeah what that uh okay try doing it this
  1194. 54:40way try just bringing the other t to the
  1195. 54:43other side of the equation so you'll
  1196. 54:45have t * 10 6 * EP Epsilon + 1 over
  1197. 54:50Alpha is equal to 1
  1198. 54:52Alpha what you say again try bringing
  1199. 54:55the T term t Alpha to that side of the
  1200. 54:57equation and factoring out the T the sub
  1201. 55:0110
  1202. 55:026 bring this one to the side and then
  1203. 55:04factor out the T sub 6 on the
  1204. 55:13left no no don't divide don't divide
  1205. 55:17okay just just bring this over and then
  1206. 55:20factor of T so you can then divide so
  1207. 55:24does setal zer this saying subtract
  1208. 55:41this okay
  1209. 55:54plus off
  1210. 55:56and now you got it
  1211. 56:14yeah okay nicely done Adam so that's
  1212. 56:18what Adam got 1 over Alpha + 1 Alpha
  1213. 56:21plus e sub 10 6 now remember that Alpha
  1214. 56:26uh what where do we use Alpha
  1215. 56:28before well it turns out that this thing
  1216. 56:33up here is equal exactly to the Proto
  1217. 56:36coefficient of the upper tail of the
  1218. 56:37income
  1219. 56:39distribution
  1220. 56:41um so uh what this says is that the
  1221. 56:47lower is
  1222. 56:48Alpha right the higher should be taxes
  1223. 56:52and the higher is the elasticity the
  1224. 56:54lower should be taxes right
  1225. 56:57in
  1226. 56:58particular if 1 over Alpha is greater
  1227. 57:02than the our other measure of inequality
  1228. 57:06then we're going to tend to make taxes
  1229. 57:09more Progressive that is the rate at the
  1230. 57:10top should be higher than it is
  1231. 57:13throughout and it will tend to be more
  1232. 57:16Progressive if the rich have lower
  1233. 57:18elasticity than most Americans
  1234. 57:20do
  1235. 57:21right so those are the conditions under
  1236. 57:24which things are progressive okay
  1237. 57:26so to get a sense for uh Sigma let's
  1238. 57:31first assume that the distribution of
  1239. 57:33income is log
  1240. 57:34logistic um that means that it takes
  1241. 57:37this form turns out then that beta is
  1242. 57:39equal to one over the Genny coefficient
  1243. 57:42which is about 045 in the United States
  1244. 57:44and the mean income turns out to be
  1245. 57:47equal to this which uh mean income is
  1246. 57:50about 46,000 in the US and that gives us
  1247. 57:54that the alpha coefficient sorry this is
  1248. 57:56a little bit confusing this is the alpha
  1249. 57:57for the log logistic distribution not
  1250. 57:59the alpha for the upper tail of the
  1251. 58:01income distribution is uh that and so
  1252. 58:05then you get that Sigma is a function of
  1253. 58:07T looks approximately like this so um
  1254. 58:13if uh we
  1255. 58:16then uh plug that into our previous
  1256. 58:19equation Sigma over the elasticity plus
  1257. 58:22uh Sigma we get curves looking like this
  1258. 58:26that determine what the optimal tax rate
  1259. 58:28is so if the elasticity is .1 optimal
  1260. 58:32taxes are about uh SE
  1261. 58:3765% or so if elasticity is.3 optimal
  1262. 58:41taxes are about um uh 40 uh 7% and as
  1263. 58:48elasticity increases optimal taxes
  1264. 58:51fall okay calcul yes well sorry so you
  1265. 58:54used um Ed a measure of inequality and
  1266. 58:57average income to determine like the
  1267. 58:58spread of income ranges yeah but um how
  1268. 59:01did you like how did you choose that
  1269. 59:03this still be like the distri
  1270. 59:05distribution function to be log logistic
  1271. 59:07you mean or like why would it be log
  1272. 59:09logistic well just because that seems to
  1273. 59:11be good approximation if you look at
  1274. 59:12more detailed data about the US income
  1275. 59:14distribution the log logistic
  1276. 59:16distribution over most of the range
  1277. 59:17seems to be pretty good it's not good at
  1278. 59:19the top part of the income distribution
  1279. 59:21at
  1280. 59:22all but um this is mostly like our
  1281. 59:25average tax rate so it's mostly going to
  1282. 59:27be dependent on the things like the
  1283. 59:29Genny that determine the average income
  1284. 59:31not uh income inequality over the main
  1285. 59:34range not over the very top was like one
  1286. 59:37of the reasons you chose it because it
  1287. 59:38just includes the Gen coefficient was
  1288. 59:40that yeah I mean you can also do that
  1289. 59:42with log normal but it's a slightly more
  1290. 59:44complicated transformation but yeah
  1291. 59:47right sorry on that last slide like uh
  1292. 59:50what do what does each line
  1293. 59:54mean so each of these Cur curves
  1294. 59:56represents Sigma of T divided by the
  1295. 59:59elasticity plus Sigma of T okay which
  1296. 1:00:02was what we said was the right hand side
  1297. 1:00:04of the optimal tax formula so and the
  1298. 1:00:07left hand side is the tax rate so we
  1299. 1:00:08just intersect this with the 45° line to
  1300. 1:00:10get the optimal
  1301. 1:00:12taxes okay calculating Alpha is even
  1302. 1:00:17easier so the upper part of the income
  1303. 1:00:19distribution has a Proto tail which
  1304. 1:00:21let's say is equal to 1.5 though it's
  1305. 1:00:24somewhere between 1.5 and 3
  1306. 1:00:27if you then just go through and
  1307. 1:00:28calculate what I bar is under a Proto
  1308. 1:00:32distribution uh you get that it's equal
  1309. 1:00:34to 10
  1310. 1:00:366 * Alpha over 1 + Alpha and so that
  1311. 1:00:40gives you that I bar 10 6 over I 10 6 -
  1312. 1:00:4310 6 is exactly equal to Alpha so I
  1313. 1:00:46named it Alpha because it was the upper
  1314. 1:00:48tail of a prto
  1315. 1:00:51distribution prto distributions always
  1316. 1:00:53have the property that if you take the
  1317. 1:00:55average value of income above some level
  1318. 1:00:58divided by that average value minus that
  1319. 1:01:00level you always get a constant which is
  1320. 1:01:02equal to Alpha okay so if you then plug
  1321. 1:01:06into the formula with the elasticities
  1322. 1:01:07of
  1323. 1:01:080.13.5 and 1 you get optimal taxes of
  1324. 1:01:1187. 6957 and4 as compared to Optimal
  1325. 1:01:16taxes for the same elasticities of 6748
  1326. 1:01:2038 and
  1327. 1:01:2126 uh under for the main part of the
  1328. 1:01:25income distribution
  1329. 1:01:26now of course the elasticity is for
  1330. 1:01:28these different groups is going to be
  1331. 1:01:29crucial but this tends to lean us
  1332. 1:01:31towards having Progressive taxes and the
  1333. 1:01:33main reason is because inequality is so
  1334. 1:01:35high at the top end of the income
  1335. 1:01:36distribution if we hadn't been having
  1336. 1:01:38this dramatic increase of inequality at
  1337. 1:01:40the top end then we wouldn't have wanted
  1338. 1:01:42to have more Progressive taxes so the
  1339. 1:01:45reason why you tend to have this is
  1340. 1:01:48because inequality has been growing more
  1341. 1:01:50at the top end of the distribution than
  1342. 1:01:52uh throughout the middle range of the
  1343. 1:01:54jny coefficient
  1344. 1:01:57okay now there yeah Adam I just a
  1345. 1:02:00question so is this pretty much like
  1346. 1:02:02with the look of the elasticity and the
  1347. 1:02:03fact that this pretty much just like
  1348. 1:02:05static view attack is like not the
  1349. 1:02:06effect of like increase productivity
  1350. 1:02:09over time well okay remember that when
  1351. 1:02:12we talked about static models we can
  1352. 1:02:14have short-run static models and long
  1353. 1:02:16run static models so the issue is not
  1354. 1:02:17really about whether it's static not
  1355. 1:02:19it's about how longterm you're thinking
  1356. 1:02:21about things and that's what I'm about
  1357. 1:02:23to bring in so almost all the evidence
  1358. 1:02:25that we have about the effects of taxes
  1359. 1:02:28is based on short run changes right um
  1360. 1:02:33and this can either bias things upward
  1361. 1:02:37or downward so a really short run change
  1362. 1:02:40might lead people to work less but they
  1363. 1:02:42might just work more the next year or
  1364. 1:02:43more importantly they might like
  1365. 1:02:44manipulate their taxes to make it look
  1366. 1:02:47like they had less income this year and
  1367. 1:02:48then that it came in the next year right
  1368. 1:02:50to take advantage of the lower taxes but
  1369. 1:02:52on the other hand as you're pointing out
  1370. 1:02:54at them there might be longer term
  1371. 1:02:56things that higher taxes do for example
  1372. 1:02:58it might change the types of careers
  1373. 1:03:00people do it might change whether people
  1374. 1:03:02get a good education in order to get a
  1375. 1:03:05higher paying job it might change
  1376. 1:03:07whether people go into the labor force
  1377. 1:03:08at all until they get older it might
  1378. 1:03:11change uh like the whole culture of a
  1379. 1:03:13country that people are just like lazy
  1380. 1:03:15in Europe because and everything thinks
  1381. 1:03:19that's acceptable because taxes are
  1382. 1:03:20lower right are higher right okay so
  1383. 1:03:24these measures has shown that the labor
  1384. 1:03:27Supply elasticity of the rich is very
  1385. 1:03:30low but their taxable income elasticity
  1386. 1:03:33that is the total amount that they're
  1387. 1:03:35reporting earning e even though they
  1388. 1:03:37don't work less when taxes rise at least
  1389. 1:03:39in the short term they do report earning
  1390. 1:03:42a lot uh less and uh why might that be
  1391. 1:03:46the case uh is Kim here I don't think he
  1392. 1:03:48is no um Can somebody else guess why
  1393. 1:03:52that might be the case uh yeah myy uh
  1394. 1:03:56like loopholes in the tax system
  1395. 1:03:58basically yeah they can shift their
  1396. 1:04:00income over time they can make it look
  1397. 1:04:02like they earned
  1398. 1:04:04income later right or they might just uh
  1399. 1:04:09put more effort when taxes are higher
  1400. 1:04:10into evading taxes that's another thing
  1401. 1:04:13right yeah so could it also be that
  1402. 1:04:16because they value income more in the
  1403. 1:04:18present they just underreports that then
  1404. 1:04:20when they're paying taxes on more in the
  1405. 1:04:22future it's still discounted
  1406. 1:04:26sorry say that again so if they
  1407. 1:04:28underreport their income in the short
  1408. 1:04:31run yeah it could just be because they
  1409. 1:04:33value it more now so if they have to
  1410. 1:04:34report it in the future even though
  1411. 1:04:36they're paying taxes on on that what do
  1412. 1:04:39you mean by value it more now in other
  1413. 1:04:41words it's not discounted
  1414. 1:04:43now yeah I mean but that's why they're
  1415. 1:04:45substituting they're like making it look
  1416. 1:04:47like they earned the income later in
  1417. 1:04:49order to try to pay less taxes right
  1418. 1:04:52yeah isn't that ask asking why
  1419. 1:04:56well no but I mean of course the reason
  1420. 1:04:58why they're doing that is to pay less
  1421. 1:04:59taxes right um yeah so uh you
  1422. 1:05:06know so I think a lot of people think
  1423. 1:05:09the right number here is at highest
  1424. 1:05:11about. 3 and maybe closer to 0.1 on the
  1425. 1:05:14other hand on the middle class labor
  1426. 1:05:15Supply elasticity seems to be a bit
  1427. 1:05:17higher because more middle class people
  1428. 1:05:21uh tend to say for example women uh in
  1429. 1:05:25the labor force might stay at home if
  1430. 1:05:27the taxes get higher
  1431. 1:05:29um and that leads to about 40% average
  1432. 1:05:33income tax rising to about 80% at the
  1433. 1:05:35top which is really quite Progressive
  1434. 1:05:38right so one possible interpretation
  1435. 1:05:41that Emanuel sias and uh Peter diamond
  1436. 1:05:43and uh Toma come take from this is
  1437. 1:05:46that we should have a much higher and
  1438. 1:05:48more progressive tax system but some
  1439. 1:05:51have also argued that the long run labor
  1440. 1:05:53Supply elasticity is much higher than
  1441. 1:05:54this uh as Adam was sort of suggesting
  1442. 1:05:58okay so let me talk a little bit about
  1443. 1:06:00some of these long run things and
  1444. 1:06:02whether they actually mean that we
  1445. 1:06:03should have uh lower taxes or not okay
  1446. 1:06:08my view is that basically no ambitious
  1447. 1:06:11intelligent person is ever going to
  1448. 1:06:12slack off and just not work hard because
  1449. 1:06:14of incentives and that's why these labor
  1450. 1:06:16Supply elasticities are so low but on
  1451. 1:06:18the other hand the choice of the career
  1452. 1:06:20that you go into is very affected by
  1453. 1:06:22incentives so for example in the 1950s
  1454. 1:06:25most PE there used to be a large number
  1455. 1:06:27of people going into Academia government
  1456. 1:06:30and
  1457. 1:06:31engineering and today almost everybody
  1458. 1:06:33goes into Finance right from top schools
  1459. 1:06:35right and the I think an important
  1460. 1:06:38reason is the relative wage that you
  1461. 1:06:39earn in finance over a lifetime is about
  1462. 1:06:41three or four times higher now relative
  1463. 1:06:44to uh those other professions than it
  1464. 1:06:46was in the
  1465. 1:06:471950s and uh so that increased by about
  1466. 1:06:51three or four times those relative wages
  1467. 1:06:53but in response the relative proportion
  1468. 1:06:55of people going into Finance compared to
  1469. 1:06:57those other things changed by about 10
  1470. 1:06:59times so that suggest a giant
  1471. 1:07:01elasticity right um and so under the
  1472. 1:07:05standard theory that would say giant
  1473. 1:07:07elasticity we should have low taxes
  1474. 1:07:09because if we don't have low taxes
  1475. 1:07:10everyone's going to waste society's
  1476. 1:07:12money by becoming academics government
  1477. 1:07:15you know everyone all these people who
  1478. 1:07:16could be so productive being in finance
  1479. 1:07:18are instead going to do all these low
  1480. 1:07:20productivity professions like
  1481. 1:07:22engineering Academia and government
  1482. 1:07:24right so the the question is do you
  1483. 1:07:26really believe that logic uh you know is
  1484. 1:07:29the world would the world really be
  1485. 1:07:30better if we had lower taxes so that
  1486. 1:07:32everyone went into Finance perhaps you
  1487. 1:07:35know maybe professions get paid
  1488. 1:07:37something that's not exactly the same as
  1489. 1:07:39their social value right um and so this
  1490. 1:07:42is an alternative basis for optimal
  1491. 1:07:44taxation not redistribution but charging
  1492. 1:07:47people a tax rate uh that reflects the
  1493. 1:07:50externalities created by their
  1494. 1:07:52profession and in fact I think this does
  1495. 1:07:54a good job matching what you hear Karl
  1496. 1:07:57Marx writing so Karl Marx doesn't say we
  1497. 1:07:59should tax the rich because they'll keep
  1498. 1:08:02working despite the fact that we tax
  1499. 1:08:05them which is what this model would
  1500. 1:08:07require and Ein Rand doesn't write in
  1501. 1:08:09fact she writes the opposite that oh
  1502. 1:08:11don't tax the rich because they won't
  1503. 1:08:12work if you tax them right uh instead
  1504. 1:08:17the Ein Rand writes that the rich are
  1505. 1:08:18doing wonderful things that they're
  1506. 1:08:19making the world a better place and that
  1507. 1:08:21the poor are you know not doing anything
  1508. 1:08:24good and uh and Marx writes that the
  1509. 1:08:27rich are parasites and that's why we
  1510. 1:08:28should tax them right um and so what we
  1511. 1:08:32did in this paper that I recently wrote
  1512. 1:08:34called Taxation and the allocation of
  1513. 1:08:36talent is that we tried to calibrate all
  1514. 1:08:40of these
  1515. 1:08:41things based on uh the distribution of
  1516. 1:08:44incomes that exist in different
  1517. 1:08:46professions and the views of different
  1518. 1:08:48groups about how much externalities
  1519. 1:08:50different professions have so uh here we
  1520. 1:08:54don't care at all about about
  1521. 1:08:55redistribution we're just trying to
  1522. 1:08:57charge different incomes the
  1523. 1:08:59externalities that they're likely to be
  1524. 1:09:00creating and if you take a view of
  1525. 1:09:02someone from the tea party that leads to
  1526. 1:09:04basically no taxes or even slightly
  1527. 1:09:06negative taxes whereas for Occupy Wall
  1528. 1:09:09Street views you can look at what they
  1529. 1:09:11are this leads to quite high taxes uh
  1530. 1:09:14for my personal views which are very
  1531. 1:09:16similar to my co-author Ben Lockwood it
  1532. 1:09:17leads to pretty modest but positive
  1533. 1:09:19taxes and for my very skeptical
  1534. 1:09:21co-author who doesn't believe that
  1535. 1:09:22there's any externalities it leads to
  1536. 1:09:24near zero taxes but you can just go
  1537. 1:09:26online plug in your own views about the
  1538. 1:09:29productivity of different professions on
  1539. 1:09:31our applet and it will tell you what you
  1540. 1:09:33think optimal taxes should be so this is
  1541. 1:09:34a very different view of of what optimal
  1542. 1:09:37taxation is yeah philli
  1543. 1:09:39um what do you want to look closer to
  1544. 1:09:43the margin of the profession than the
  1545. 1:09:46average because when you change a tax
  1546. 1:09:48rates you're mostly going to be
  1547. 1:09:50eliminating or at least just for small
  1548. 1:09:52changes you're going to be mostly
  1549. 1:09:54eliminating or adding margin yeah I mean
  1550. 1:09:56the the the right way to think about the
  1551. 1:09:57numbers that you plug in is not the
  1552. 1:09:59average externality of people but the
  1553. 1:10:01average externality of the marginal
  1554. 1:10:02people people who just drop in or drop
  1555. 1:10:05out should we look at the Marg average
  1556. 1:10:08exality of marginal home sure yeah
  1557. 1:10:11that's the right way to think about
  1558. 1:10:14it good thanks guys

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