These days – especially on the internet, although usually out side of a formal philosophical context, a lot of outspoken atheists take the title “rationalist.” Within popular philosophy, therefore (again, in the context of internet based discussion), if a person uses the word “rationalist” it is often assumed that one is talking about opposition to religion. Groups like the New Zealand Association of Rationalists and Humanists expect people to assume, based on the name of the group, that the group’s members are not religious (I won’t delve into the use of the word “humanist” just now, but that’s fascinating too).

I thought it might be helpful to point out, therefore, what rationalism really is. The best way to do this is to compare rationalism with its philosophical rival, empiricism. I’ll be brief, because brief explanations are the easiest to remember.

Rationalists, like Descartes or Kant, believed that (some) knowledge and concepts are innate: We are born with built in knowledge concepts. Candidates for this sort of thing might be moral intuitions, mathematical truisms, or perhaps a whole range of common sense judgements summed up as “folk psychology.”

Empiricists, like Locke, Berkley and Hume, believed that everything is learned via experience. We are born as a blank slate, and we accumulate knowledge and concepts as we go.

Every now and then I have a geeky chuckle over the fact that a lot of contemporary sceptics who like to call themselves “rationalists” are in fact empiricists after all. Yes, mine is truly a sad existence….

Further reading