It seems that we are prone to a particular simplification in analyzing the behavior of others and of ourselves. When someone does something differently than we would, our immediate explanation is of the ‘stupid lazy or - evil’ type. When we are confronted by having done something differently than others would have, our immediate explanation is almost never ‘stupid lazy or - evil’ and often the exact opposite we thought long a hard about it. Now, most of us know that we are not smarter, more conscientious, and more moral than absolutely everyone else we meet. Either we are deluding ourselves or underestimating others or both on a fairly regular basis.
I remember first thinking about this years ago when I read someone talking about anthropology and how it is a good idea to assume that everyone does what they do for perfectly rational reasons. If you don’t make that assumption, you are not going to be able to understand strange cultures. I was really blown away by that thought. And I used it. When someone surprised me with their actions, I just assumed they had a good reason but I usually didn’t think about what the reason might be unless I was very curious. What started to happen was that a third person would be somewhat exasperated by the strange behaviour and say, Why did they do that? Quite often a plausible reason would jump into my head and I would supply it. Oh, they probably did it because of x. The whole thing would be a little magical.
Then I learned that in experiments with split-brained subjects, the speaking left hemisphere would make up reasons for the (to it) strange behaviour of the non-speaking right hemisphere. The left hemisphere appeared to be unaware that it was guessing the motivation of the right. I also learned that people doing inappropriate things under hypnotic suggestion would give plausible explanations when asked why they had done those things. This seemed essentially the same trick as my ‘everyone is rational’ one.
There also is a trickle of evidence that our knowledge of our own motivation can be faulty and that we are pretty good at fabricating justification when necessary.
So now comes the realization that we treat ourselves like I have learned to treat others. We just assumed that we are rational (and not stupid-lazy-evil) and then went a motivation is needed, we guess. And given that we are pretty good at this guessing, we are usually right enough. It is when this mechanism is used in unusual circumstances (like hypnosis) or applied to another’s mind, that we can see that it is just a mechanism for making guesses. Nice trick!