Much philosophy relies on overall comparisons - on comparisons that result, somehow, from how things measure up in various relevant ways.  Examples include comparisons of overall similarity in metaphysics, and of overall theoretical value in epistemology.  In the talk, I will set out a quite general difficulty with them.  It derives from a well-known difficulty with the idea of a social preference ranking that assimilates various individual preferences.  There are, we will see, crucial differences between the overall comparisons of philosophy and social preferences.  Having pointed them out, I will state a variant of Arrow’s theorem of social choice that can serve as a sort of chart for theoreticians developing accounts of overall comparisons.  It warns of rocks and hard places where no such account can ever go.