Monthly Archives: November 2006

Bias is something bad from an epistemological point of view, but what exactly is it and how is it distinct from other kinds of epistemological error?

Let’s start with one remark Robin made in passing: "Bias is just avoidable systematic error." One big question here is what makes a systematic error avoidable. For example, suppose somebody has never heard about overconfidence bias. When such a person (erroneously) rates herself above average on most dimensions without strong specific evidence, is she making an avoidable error?

It seems to be avoidable only in the sense that there is information which she doesn’t have but which she could get which would make it possible for her to correct her beliefs about her own abilities. But in this sense, we would be biased whenever we lack some piece of information that bears on some broad domain. Socractes would be biased merely by being ignorant of evolution theory, neuroscience, physics, etc. This seems too broad.

Conversely, if she is systematically overestimating her own abilities, it seems she is biased even if these errors are unavoidable. Suppose she does learn about overconfidence bias, but for some deep psychological reasons simply cannot shake off the illusion. The error is systematic and unavoidable, yet I’d say it is a bias.

Here is an alternative explication that I’d like to put forward tentatively for discussion: A bias is a non-rational factor that systematically pushes one’s beliefs in some domain in one direction.

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