Lewis’ words ground me when major scientific issues arise. I as a voting citizen—and, more importantly, a human charged with wise dominion over the earth—am responsible to evaluate the public arguments as best I can, which is something I do through major (responsible) news sources. But I generally do not have the training or the expertise to make an independent determination on scientific matters, and most other people don’t either. I have to trust some authority.
The debate for us non-experts really boils down to one question: whom do you trust? I would suggest that’s why the controversy over climate change has fallen down predictable political lines, and also why people are so passionate about it. The less they can defend their cause with reasoned arguments (and how many non-specialists really have a handle on the complicated data?), the more partisans ramp up the rhetorical force.*
Abortion is one scientific issue that’s different. Positions don’t always fall down neat political lines, especially among the electorate. Some Democrats enlist in the pro-life cause, some Republicans don’t. The moral issues in this debate are not opaque to all but specialists; they’re on the ultrasound photos for all to see.
*This doesn’t mean that reasoned arguments are always to be trusted over rhetorical force. Both are appropriate and should work in harmony.