I'll bite the bullet and say global warming is the perfect example here. It's pretty clear to me that many people hold their positions on this issue - pro and contra - for political/social reasons rather than evidential ones.

Unfortunately that often seems to be the case when there are vested interests in the answer going one way or the other.

The impact of genetics on behaviour is another example. Most of the educated people I know are ultra-behaviorists, so if I see somebody argue that genes matter (but aren't everything), they definitely get brownie points. Especially since such a view tends to be seen as vaguely quasi-racist.