Also the key question is not how long they've thought about the issue but whether they have thought about it from perspectives other then their own and how many different perspectives they've thought about it from.
I disagree that that is the key question. I have a model of a person slightly less smart than the average Less Wronger but who has thought quite a bit more about tax policy. These people tend to converge on similar views about tax policy. The fact that this group generally doesn't benefit from most tax deductions certainly may make it easier to oppose them: but that isn't an argument that they are biased. Obviously it is those who benefit from particular deductions whose judgments we ought to be suspicious of.
That's why, after all, these deductions remain in place despite being really bad policy. They benefit the groups that sway elections.
I was thinking about the hazards of bad government, and wondering if there was a way for the LW community to do something to oppose them, and it occurred to me that we might be picking up the problem by the wrong end.
The usual way of thinking about political action is to start with one's political identity (progressive, libertarian, whatever), and that's likely to put one at odds with people who have opposed identities.
Instead, I believe there are projects which could appeal to rationalists across a wide range of the political spectrum. A couple I can think of are opposing the war on drugs and improving judicial systems. Any other suggestions?