(Like Jiro's comment, don't read this if you're going to take the poll but haven't yet.)

So this doesn't prove that people find anything convincing with a good explanation, but rather that people find things unconvincing with a poor one.

Fair point. The conclusion to draw, then, should be a more general one: given an observation O and an explanation E of O, people can over-weight E as a piece of evidence about O's probability. (If E sounds plausible it might be taken as de facto proof of O; if E sounds implausible it might be taken as a disconfirmation of O.)

Edit2: The Gallup poll at http://www.gallup.com/poll/126581/generational-differences-abortion-narrow.aspx gives a different impression of abortion opinions among the young. If you look at a longer time scale, younger people support abortion more and satt's poll inly shows that they do not because the people who were young in those earlier years got older and kept their opinions.

This strikes me as I-was-not-wrong-but-I-was-almost-right reasoning. Had I posted this in 1992, claim 3 would indeed have been true. But it hasn't been true for something like a decade, and at some point informed people should update their beliefs.