Hume's Missing Shade of Blue: A New Solution

Abstract

What to do with the missing shade of blue (MSB)? Some have argued that Hume's famous thought experiment undermines his central doctrine – the ‘copy principle’ – such that he should have revised his whole theory in light of it. Others contend that the MSB is not a true or actual counterexample to the copy principle, but merely an apparent or conceivable one, so that he had no such obligation to revise. In this essay, I argue that even if the MSB is a true counterexample, Hume would not have been obligated to revise his theory, given methodological resources he makes available to himself elsewhere in his work and his overarching empiricist aims. And I offer a new suggestion for why he might have included and even highlighted the MSB in his writings despite its being so very vexing and peculiar.