This is part of a semi-monthly reading group on Eliezer Yudkowsky's ebook, Rationality: From AI to Zombies. For more information about the group, see the announcement post.

Welcome to the Rationality reading group. This fortnight we discuss Part E: Overly Convenient Excuses (pp. 211-252). This post summarizes each article of the sequence, linking to the original LessWrong post where available.

Essay: Rationality: An Introduction

E. Overly Convenient Excuses

46. The Proper Use of Humility - There are good and bad kinds of humility. Proper humility is not being selectively underconfident about uncomfortable truths. Proper humility is not the same as social modesty, which can be an excuse for not even trying to be right. Proper scientific humility means not just acknowledging one's uncertainty with words, but taking specific actions to plan for the case that one is wrong.

47. The Third Alternative - People justify Noble Lies by pointing out their benefits over doing nothing. But, if you really need these benefits, you can construct a Third Alternative for getting them. How? You have to search for one. Beware the temptation not to search or to search perfunctorily. Ask yourself, "Did I spend five minutes by the clock trying hard to think of a better alternative?"

48. Lotteries: A Waste of Hope - Some defend lottery-ticket buying as a rational purchase of fantasy. But you are occupying your valuable brain with a fantasy whose probability is nearly zero, wasting emotional energy. Without the lottery, people might fantasize about things that they can actually do, which might lead to thinking of ways to make the fantasy a reality. To work around a bias, you must first notice it, analyze it, and decide that it is bad. Lottery advocates are failing to complete the third step.

49. New Improved Lottery - If the opportunity to fantasize about winning justified the lottery, then a "new improved" lottery would be even better. You would buy a nearly-zero chance to become a millionaire at any moment over the next five years. You could spend every moment imagining that you might become a millionaire at that moment.

50. But There's Still A Chance, Right? - Sometimes, you calculate the probability of a certain event and find that the number is so unbelievably small that your brain really can't keep track of how small it is, any more than you can spot an individual grain of sand on a beach from 100 meters off. But, because you're already thinking about that event enough to calculate the probability of it, it feels like it's still worth keeping track of. It's not.

51. The Fallacy of Gray - Nothing is perfectly black or white. Everything is gray. However, this does not mean that everything is the same shade of gray. It may be impossible to completely eliminate bias, but it is still worth reducing bias.

52. Absolute Authority - Those without the understanding of the Quantitative Way will often map the process of arriving at beliefs onto the social domains of Authority. They think that if Science is not infinitely certain, or if it has ever admitted a mistake, then it is no longer a trustworthy source, and can be ignored. This cultural gap is rather difficult to cross.

53. How to Convince Me That 2 + 2 = 3 - The way to convince Eliezer that 2+2=3 is the same way to convince him of any proposition, give him enough evidence. If all available evidence, social, mental and physical, starts indicating that 2+2=3 then you will shortly convince Eliezer that 2+2=3 and that something is wrong with his past or recollection of the past.

54. Infinite Certainty - If you say you are 99.9999% confident of a proposition, you're saying that you could make one million equally likely statements and be wrong, on average, once. Probability 1 indicates a state of infinite certainty. Furthermore, once you assign a probability 1 to a proposition, Bayes' theorem says that it can never be changed, in response to any evidence. Probability 1 is a lot harder to get to with a human brain than you would think.

55. 0 And 1 Are Not Probabilities - In the ordinary way of writing probabilities, 0 and 1 both seem like entirely reachable quantities. But when you transform probabilities into odds ratios, or log-odds, you realize that in order to get a proposition to probability 1 would require an infinite amount of evidence.

56. Your Rationality Is My Business - As a human, I have a proper interest in the future of human civilization, including the human pursuit of truth. That makes your rationality my business. The danger is that we will think that we can respond to irrationality with violence. Relativism is not the way to avoid this danger. Instead, commit to using only arguments and evidence, never violence, against irrational thinking.

This has been a collection of notes on the assigned sequence for this fortnight. The most important part of the reading group though is discussion, which is in the comments section. Please remember that this group contains a variety of levels of expertise: if a line of discussion seems too basic or too incomprehensible, look around for one that suits you better!

The next reading will cover Part F: Politics and Rationality (pp. 255-289). The discussion will go live on Wednesday, 29 July 2015, right here on the discussion forum of LessWrong.