In Policy Debates Should Not Appear One-Sided, Eliezer Yudkowsky argues that arguments on questions of fact should be one-sided, whereas arguments on policy questions should not:
On questions of simple fact (for example, whether Earthly life arose by natural selection) there's a legitimate expectation that the argument should be a one-sided battle; the facts themselves are either one way or another, and the so-called "balance of evidence" should reflect this. Indeed, under the Bayesian definition of evidence, "strong evidence" is just that sort of evidence which we only expect to find on one side of an argument.
But there is no reason for complex actions with many consequences to exhibit this onesidedness property.
The reason for this is primarily that natural selection has caused all sorts of observable phenomena. With a bit of ingenuity, we can infer that natural selection has caused them, and hence they become evidence for natural selection. The evidence for natural selection thus has a common cause, which means that we should expect the argument to be one-sided.
In contrast, even if a certain policy, say lower taxes, is the right one, the rightness of this policy does not cause its evidence (or the arguments for this policy, which is a more natural expression), the way natural selection causes its evidence. Hence there is no common cause of all of the valid arguments of relevance for the rightness of this policy, and hence no reason to expect that all of the valid arguments should support lower taxes. If someone nevertheless believes this, the best explanation of their belief is that they suffer from some cognitive bias such as the affect heuristic.
(In passing, I might mention that I think that the fact that moral debates are not one-sided indicates that moral realism is false, since if moral realism were true, moral facts should provide us with one-sided evidence on moral questions, just like natural selection provides us with one-sided evidence on the question how Earthly life arose. This argument is similar to, but distinct from, Mackie's argument from relativity.)
Now consider another kind of factual issues: multiple factor explanations. These are explanations which refer to a number of factors to explain a certain phenomenon. For instance, in his book Guns, Germs and Steel, Jared Diamond explains the fact that agriculture first arose in the Fertile Crescent by reference to no less than eight factors. I'll just list these factors briefly without going into the details of how they contributed to the rise of agriculture. The Fertile Crescent had, according to Diamond (ch. 8):
- big seeded plants, which were
- abundant and occurring in large stands whose value was obvious,
- and which were to a large degree hermaphroditic "selfers".
- It had a higher percentage of annual plants than other Mediterreanean climate zones
- It had higher diversity of species than other Mediterreanean climate zones.
- It has a higher range of elevations than other Mediterrenean climate zones
- It had a great number of domesticable big mammals.
- The hunter-gatherer life style was not that appealing in the Fertile Crescent
(Note that all of these factors have to do with geographical, botanical and zoological facts, rather than with facts about the humans themselves. Diamond's goal is to prove that agriculture arose in Eurasia due to geographical luck rather than because Eurasians are biologically superior to other humans.)
Diamond does not mention any mechanism that would make it less likely for agriculture to arise in the Fertile Crescent. Hence the score of pro-agriculture vs anti-agriculture factors in the Fertile Crescent is 8-0. Meanwhile no other area in the world has nearly as many advantages. Diamond does not provide us with a definite list of how other areas of the world fared but no non-Eurasian alternative seem to score better than about 5-3 (he is primarily interested in comparing Eurasia with other parts of the world).
Now suppose that we didn't know anything about the rise of agriculture, but that we knew that there were eight factors which could influence it. Since these factors would not be caused by the fact that agriculture first arose in the Fertile Crescent, the way the evidence for natural selection is caused by the natural selection, there would be no reason to believe that these factors were on average positively probabilistically dependent of each other. Under these conditions, one area having all the advantages and the next best lacking three of them is a highly surprising distribution of advantages. On the other hand, this is precisely the pattern that we would expect given the hypothesis that Diamond suffers from confirmation bias or another related bias. His theory is "too good to be true" and which lends support to the hypothesis that he is biased.
In this particular case, some of the factors Diamond lists presumably are positively dependent on each other. Now suppose that someone argues that all of the factors are in fact strongly positively dependent on each other, so that it is not very surprising that they all co-occur. This only pushes the problem back, however, because now we want an explanation of a) what the common cause of all of these dependencies is (it being very improbable that they all would correlate in the absence of such a common cause) and b) how it could be that this common cause increases the probability of the hypothesis via eight independent mechanisms, and doesn't decrease it via any mechanism. (This argument is complicated and I'd be happy on any input concerning it.)
Single-factor historical explanations are often criticized as being too "simplistic" whereas multiple factor explanations are standardly seen as more nuanced. Many such explanations are, however, one-sided in the way Diamond's explanation is, which indicates bias and dogmatism rather than nuance. (Another salient example I'm presently studying is taken from Steven Pinker's The Better Angels of Our Nature. I can provide you with the details on demand.*) We should be much better at detecting this kind of bias, since it for the most part goes unnoticed at present.
Generally, the sort of "too good to be true"-arguments to infer bias discussed here are strongly under-utilized. As our knowledge of the systematic and predictable ways our thought goes wrong increase, it becomes easier to infer bias from the structure or pattern of people's arguments, statements and beliefs. What we need is to explicate clearly, preferably using probability theory or other formal methods, what factors are relevant for deciding whether some pattern of arguments, statements or beliefs most likely is the result of biased thought-processes. I'm presently doing research on this and would be happy to discuss these questions in detail, either publicly or via pm.
*Edit: Pinker's argument. Pinker's goal is to explain why violence has declined throughout history. He lists the following five factors in the last chapter:
- The Leviathan (the increasing influence of the government)
- Gentle commerce (more trade leads to less violence)
- Feminization
- The expanding (moral) circle
- The escalator of reason
- Weaponry and disarmanent (he claims that there are no strong correlations between weapon developments and numbers of deaths)
- Resource and power (he claims that there is little connection between resource distributions and wars)
- Affluence (tight correlations between affluence and non-violence are hard to find)
- (Fall of) religion (he claims that atheist countries and people aren't systematically less violen
Firstly, giving reasons for your own choices is something a bit different from explaining events over which you had no control. I'd rather concentrate on the latter cases.
Sure. I do think that Diamond should have provided pros and cons (and Pinker even more so). However, this discussion has been very useful to me in that I realize that others have different intuitions.
Suppose that there is a convention which says that it's ok to omit countervailing factors (which I'm not sure there is). In that case, Diamond and Pinker are at least to some extent forgiven - they are merely following a convention. However, then I'd say that the convention should be abandoned, because I, as a reader, do want to get the full picture, and not a cherry-picked selection of factors.
--
Sure. The question kind of suggests an answer along these lines - which support the notion that there is a convention according to which we're expected only to give pro-reasons. But in this case, this is clearly absurd. Why would I want to hear about Man City's fifth best characteristic (relative to Man U) over Man U's best characteristic (relative to Man C)?
--
Generally, I also think that people have a bias against admitting bias, especially in themselves, but also in others. Philosophers and others have defended the hypothesis that humans are basically rational to absurdity, to my mind, despite the overwhelming evidence to the contrary. (See this excellent post on this, for instance. But the same goes not only for the notion of whether humans are rational in general, but also for whether any particular thought-process was rational or biased. I think that, given what we know about the ubiquity of human biases (as shown in experiments), we should be very open to the possibility that even great books like Diamond's and Pinker's are filled with inferences which are not rational but rather due to biases. This goes particularly for inferences and reasonings in messy and inexact fields. I would be very surprised if someone was able to escape to form very general historical theories such as these without falling prey to at least some biases on a major scale.
Me too - my posts tend to be too long for LW. I think it's a good idea to try to be a bit shorter and more succinct for both of us.