Unbelievable Errors defends an error theory about all normative judgements: not just moral judgements, but also judgements about reasons for action, judgements about reasons for belief, and instrumental normative judgements. This theory states that normative judgements are beliefs that ascribe normative properties, but that normative properties do not exist. It therefore entails that all normative judgements are false.

Bart Streumer also argues, however, that we cannot believe this error theory. This may seem to be a problem for the theory. But he argues that it makes this error...