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Meaningness's profile
David Chapman
David Chapman
David Chapman
@Meaningness

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David Chapman

@Meaningness

Better ways of thinking, feeling, and acting—around problems of meaning and meaninglessness; self and society; ethics, purpose, and value.

meaningness.com/about-my-sites
Joined September 2010

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    1. David Chapman‏ @Meaningness 2 Jun 2019
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      Effective Altruism uses mainly decision theory (probabilistic expected value analysis) to choose what to fund. @Chris_PK_Smith points out ways that can be misleading. https://confusopoly.com/2019/04/03/the-optimizers-curse-wrong-way-reductions/ …

      2 replies 11 retweets 64 likes
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    2. David Chapman‏ @Meaningness 2 Jun 2019
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      Applying decision theory when you have insufficient domain understanding leads to the “optimizer’s curse”: it’s a mathematical fact that you will typically choose options that have less-good outcomes than you expect. https://pubsonline.informs.org/doi/abs/10.1287/mnsc.1050.0451 …

      1 reply 2 retweets 17 likes
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    3. David Chapman‏ @Meaningness 2 Jun 2019
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      Formally, probability theory only applies in extremely restricted conditions that are rarely or never found in the real world. It is, of course, often useful when it does not quite formally apply. Some rationalists insist on applying it universally, which doesn’t go well.pic.twitter.com/yXyMkgUaSg

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    4. David Chapman‏ @Meaningness 2 Jun 2019
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      Discussion of @Chris_PK_Smith’s article here includes both useful elaboration/clarification and a display of rationalist stubbornness, digging in and insisting that decision theory MUST always work. Because otherwise, it wouldn’t always work, as it MUST!https://forum.effectivealtruism.org/posts/Wghi6hpu5gGBZHvtj/link-the-optimizer-s-curse-and-wrong-way-reductions …

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      David Chapman‏ @Meaningness 2 Jun 2019
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      When rationality doesn’t work well, it’s time to get meta-rational. That is: step outside the rational system to examine how and when and why it works, and on that basis to revise its use in a situation, select an alternative, or combine it with other systems to do better.

      11:11 AM - 2 Jun 2019
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      • Josh Marshall raggedy flan 🍮 ~ grilled with care Milan Griffes Peter Hatch James Stuber John Harlow QC Brian Heligman 😷
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        2. David Chapman‏ @Meaningness 2 Jun 2019
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          Chris suggests several meta-rational approaches to revising or replacing the use of decision theory in selecting what altruistic projects to fund. These apply more broadly to decision making in other fields.

          1 reply 1 retweet 3 likes
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        3. David Chapman‏ @Meaningness 2 Jun 2019
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          Venture capitalists address extreme uncertainty by using several quantitative and qualitative systems simultaneously, e.g.: - market size estimate - comparable-company ratios - discounted cash flow calculation - qualitative management team assessment - industry fashion trends

          1 reply 0 retweets 7 likes
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        4. David Chapman‏ @Meaningness 2 Jun 2019
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          Using multiple incommensurable rational systems is a typically meta-rational move. When they disagree, it’s often not feasible to figure out which is right, or to reconcile them. When most investment analysis methods point in the same direction, you may choose to act.pic.twitter.com/rA0ESS4YXY

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        5. David Chapman‏ @Meaningness 2 Jun 2019
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          Chris gives a concrete example in the Effective Altruism domain, namely malaria net distribution, which looks good when evaluated in many different ways. (Whereas some other projects he discusses got funded on the basis of a single dubious expected-value model.)pic.twitter.com/AFFQgnqf6r

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        6. David Chapman‏ @Meaningness 2 Jun 2019
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          When you know your probability and/or value estimates are highly uncertain, you can gather information to get better estimates. Also, your model may be wrong overall, not just its numerical parameters. Deciding how much effort to put into better understanding is meta-rational.pic.twitter.com/9jDgzi2uqN

          2 replies 1 retweet 3 likes
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        7. David Chapman‏ @Meaningness 2 Jun 2019
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          David Chapman Retweeted David Chapman

          Decision theory assumes you are constantly forced to make specified decisions. In reality, you can walk away from most situations, and that’s often sensible. Don’t make bets with Dutch bookies. Carry a musket, and if you meet a Bayesian Thug, shoot them.https://twitter.com/Meaningness/status/1001172948894466048 …

          David Chapman added,

          David Chapman @Meaningness
          Roving gangs of Bayesian thugs https://plato.stanford.edu/entries/dutch-book/ … pic.twitter.com/OgigzojVGO
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          2 replies 8 retweets 17 likes
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        8. David Chapman‏ @Meaningness 2 Jun 2019
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          The world is full of unknown unknowns, which decision theory can’t handle at all. Increasing a system’s general robustness to failure is often possible, and… might be the most effective form of altruism.pic.twitter.com/RiEKnEssp0

          1 reply 0 retweets 15 likes
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        9. End of conversation

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