ABSTRACT
The rhythms of talking and walking might be invariable enough to provide us with an intersubjective measure of time. The measure of time is thus partly a matter of convention, but not completely so. It is partly so, because we are assigning magnitudes to intervals defined in terms of instants, and there could be different ways of assigning magnitudes which we were free to adopt. Our system of assigning magnitudes needs to be internally consistent. In particular, the logic of the word 'magnitude' imposes its own requirements. Our system of assigning magnitudes needs to be coherent. Although we could, without inconsistency, assign measures purely arbitrarily, there would be no point in doing so. We could measure time by reigns of the sovereign and sittings of Parliament, much as lawyers do for dating statutes. This is sufficiently systematic and sufficiently public to be usable, and in some societies the political climate might be more important than the meteorological seasons.
