Things that challenge things I believe

This is, of course, the most interesting class of things.

I'm reading Power and Plenty at the moment. I generally think protectionism is a bad thing. But on p.347 it is argued that Britain's rise to wealth during the Industrial Revolution owed something to protectionism: that the imports of raw materials were allowed freely but those of manufactured goods restricted, which boosted the nascent manufacturing sector. That does, in fact, seem logical - though of course a cost would have been borne by consumers who would have been forced to pay artificially higher prices for manufactured goods. However, so great a benefit as a successful Industrial Revolution, one that enriched everyone, is a powerful counterweight to this disadvantage.

That does, of course, rely on the assumption that these restrictions on imports had a significant effect on the course of the Industrial Revolution, and that isn't quantified in the book.