Reba Nelson

A-theoretic conceptions of time hold that there is mind-independent passage. Recently, some B-theorists have joined them in holding that time really passes. These B-theorists diverge from A-theorists in holding that time passes in a way that does not involve commitment to a tensed picture of reality. Certain B-theorists of this type base temporal passage on relations of causal connectability, definable in spacetime. We argue that, on this causal conception, calculating the rate of passage has strange results: the rate is variable, undefined, arbitrary or zero. We argue that this presents a challenge for such B-theories.