Unlike old soldiers, the rhetoric of the great neither dies nor fades away. And so Hume's celebrated ‘is-ought’ passage still provokes debate.
Hume was worried about the relation between ought statements and those supporting them: between ‘tolerence brings peace’ or ‘is God's will’, and ‘so one ought to be tolerant’. He denies the deducibility of the latter from the former, as the ‘ought’ expresses ‘a new relation or affirmation’, ‘entirely different from the others’. And this is commonly taken as saying that the ought statement is ‘different’ and non-deducible, because it is no longer a ‘purely factual statement’, to wit one that makes another ordinarily testable truth claim.
However, recent criticism, by W. D. Hudson and others, points out that Hume says other things seemingly inconsistent with this. In the passage, he mentions ‘ought’ and ‘virtue’ interchangeably, and ‘tolerance is virtuous’ as in the same boat as ‘one ought to be tolerant’. But, also, he treats the virtue of an action as sensibly discernible by the approbation which it evokes, and takes us to mean by a virtuous action that we will approve of it on contemplation.