I think the main point, and it may be getting lost in the discussions over different psychological schools of thought, is simply to question your assumptions. What's going on inside someone's head is not measurable or provable in the sense that the atomic weight of Uranium is, and there are inevitably parts to the whole that you have no idea exist. (Just to throw gestalt psych into the hopper.)

It's a good idea in experimentation (including experimental psych) - don't just have a null hypothesis, but have a secondary competing hypothesis that isn't simply a straw man, when putting your own theories to the test. When you're debugging and you get stuck, its when you start actively coming up with these alternative explanations that you begin to hit the real problem.

Update: Re-reading the thread, I think I misunderstood something in the discussion and I'm just non-sequitizing here, and repeating dws. (And making up words like 'non-sequitizing'.) By way of salvaging the post, let me add that whether someone is a thinker or feeler seems to me to be independent of whether or not they really question their assumptions or first judgements.

-- Frag.
"Oh. Never mind." -- Miss Emily Latella.