INTRODUCTION

It’s apples and oranges, we say. Chalk and cheese.Apples and oranges is the North American term, implying incommensurability. Chalk and cheese is the British term, implying both incommensurability and incompatibility. Or, somewhat more equivocally, six of one and half a dozen of the other.This may imply either the equality of the options before us (if emphasis is placed on the identity of six and half a dozen) or the incommensurability of options that are insignificant in our lives (if emphasis is placed on the difference between one option and the other). What do we mean?