Abstract

This chapter focuses on one of the common fallacies in Western philosophy called the 'is/ought fallacy (IOF)'. Some philosophers conclude that the IOF is not a logical problem but an epistemological one, meaning that even if inferences like this one are logically valid, they cannot be used epistemologically to warrant anyone's real‐life moral beliefs. Arguments do not warrant their conclusions unless the premises of those arguments are themselves warranted, and in the real world, they say, no one would ever be warranted in believing premise. Charles Pigden argues for the illegitimacy of the move from is to ought, saying that we should understand David Hume as pointing to the conservativeness of logic. According to Pigden, logic is conservative in that “the conclusions of a valid inference are contained within the premises. You do not get out what you have not put in”.