Mellor, David Hugh (1938-)

A and B Series of Time Differentiated

The first step on the way to Mellor's theory of time is the differentiation between the A and B series of time established by McTaggart. The A series orders facts in relation to the present moment as past, present, or future. Their relation to each other does not change, but their qualification as past, present, or future changes with the flow of time. The B series orders facts or events only with respect to their successive occurrence, no matter which of them is the present one. Therefore it does not need the concept of a flowing time. In everyday language, facts involving time are usually expressed in A sentences; that is, by using tensed verbs. Mellor argues that all tensed propositions or beliefs have B facts as their truth conditions. The crucial question is what makes tensed sentences, or A sentences like “Peter arrived yesterday,” true.

Mellor's answer to this question in general is the following: A sentences have B facts as their truth condition. That means they depend, first, on facts like the time when the sentence is uttered and, second, on whether the event that is mentioned really occurred at the time that the sentence says it did. Both conditions can be expressed in B terms as follows: (1) The sentence was uttered on March 2nd, and Peter arrived on March 1st; (2) Peter really arrived on March 1st. If both conditions obtain, the A sentence is true. If the truthmakers were A facts, they would cause contradictions, because the fact that Peter arrived yesterday would have to obtain in order to make the statement true if uttered on March 2nd and not obtain to make it false when uttered on March 3rd. The central thought in Mellor's B theory is that A sentences need B truthmakers in order not to fall prey to contradictions. He does not want to do away with the way of expressing subjective perspectives of time in A sentences. On the contrary, he recognizes the necessity of A sentences and A beliefs within a concept of agency.

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