The Pioneer plaque

Julian Baggini’s The Edge of Reason, of which we have so far examined the first five chapters, ends its second part with a discussion of the distinguishing characteristics of objective rational discourse. He begins it by suggesting that the problem with the classic (Platonic, really) view of reason is that it treats reason as an heteronomous entity, something coming from the outside, imposed on us by eternal laws of logic. Instead, human reason is, well, human, i.e., autonomous, shaped from the inside, shaped by the characteristics and limitations of what it means to be human in the first place.

That said, Julian immediately qualifies, reason does have a component of heteronimity, in that it cannot simply be a self-serving instrument entirely detached from how the world actually is, but rather has to account for the brute facts of external reality. Reason, he says, is nothing…