What are you checking books for? Run experiments. Don’t go to your books about dropping weights off Pisa, just _drop weights off Pisa_. I don’t care what people are certain of: either those weights fall independently of their mass or don’t. If you are treating it like philosophy instead of science, you’ve already lost the thread.

In other words, actual enlightenment era style DIY science.

But then how do I decide whether to recycle or not, vis-à-vis global warming?

Gravity is NOT controversial and Political Science is all about philosophy.

Gravity isn’t particularly controversial these days, no. Many things that aren’t now, though—like the curvature of earth, or heliocentricity—once were; that a topic is controversial doesn’t mean there’s no right answer.

And I would agree that political science is largely concerned with philosophy, but let’s not mistake any old politicized belief as fitting under the umbrella of “political science”: that e.g. a manual recount renders any conspiracies about an automatic ballot-counting machine irrelevant to a final vote tally is a matter of common sense, not profound debate—and yet this has proved a controversial point these last few weeks.