Time seems to pass - at least, that’s what plenty of people (some philosophers included) seem to think. However, on reflection, it’s pretty baffling what this claim is supposed to amount to. Taking it literally, we might suppose that time flows literally like a river, with moments passing by like water passing from one section of the river to the next.'The Persistence of Memory' by Salvador DaliHowever, if this is the way in which time flows, it makes sense to ask the question ‘how fast does time flow?’ The problem is, we cannot answer this question without talking nonsense. A river, let’s say, flows at x cubic liters per second - there’s nothing problematic about this observation. In the case of time, the only answer we can give to the question is ‘one second per second.’ But this is not a proper rate at all - it doesn’t tell us anything about the rate of time’s flow, since it is trivially true. It reduces to 1/1, which is not a rate; it’s just ‘1’. We are none the wiser.We should therefore look to describe the passage of time in some other, perhaps metaphorical, sense. But to do this, we need to get a grip of what exactly we mean by the claim that ‘time passes.‘ Talk of events zooming out of the future, past us through the present, and into the past is all well and good, but seems pretty vague when considered in any depth. We see objects moving about, changing position - and ‘watching the world go by’ just means watching lots of these objects move about. But that this should indicate a great sweeping movement of all spatial events into the past seems unclear.

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