Are the Epistemological Principles Underlying Ethics Synthetic a priori Cognitions?

Wollaston’s principle of honesty (see Part I, chap. 2, sect. 12) is also synthetic and would be a synthetic a priori cognition if it were really self-evident. After, and in reaction to, Hume, the advocates of the synthetic a priori as the basis of ethics became more numerous. To name just a few of the more famous, they include Bishop Butler (1692-1752); Thomas Reid (1710-96), whom we have already mentioned, and many of his followers; and, in Germany, Kant and his many followers.