Benjamin S Nelson in The Philosopher's Magazine:
Atheism and agnosticism. If you ask some people, atheism is just a sexed up version of agnosticism. After all, atheism is about what you believe (or don’t believe), and agnosticism is about what you know (or don’t) — so when we say that we’re atheists, we’re just putting accent on the fact that God is really really really super unlikely. But others will say that atheism and agnosticism are perfect companions. They’ll tell you that agnosticism is just a closeted form of atheism. After all (they’ll say), since agnostics dislike being called ‘theists’, they must be atheists — the one position collapses into the other.
To see an example of this contrast in action, consider the views of Bertrand Russell and Anthony Grayling. Russell argued for atheism in public, and only called himself an agnostic among philosophers. That’s because he thinks there’s a significant gulf between atheism and agnosticism. By contrast, in a difficult-to-parse exchange with Jerry Coyne, Anthony Grayling begged to differ — an agnostic is either an atheist, or just plain irrational.
Grayling does himself a disservice by repeatedly claiming that “an assimilation of proof concerning matters of fact to proof of the demonstrative kind”, when that doesn’t really seem to be exactly what’s going on. This post is going to be my attempt to make sense of what Grayling is up to, and an argument about why he hasn’t got it right.
This fight comes down to a complaint in the theory of knowledge. Grayling’s claim is that Russell tacitly bases the distinction between atheism and agnosticism on “a quibble about proof”.