The essence of nowness runs like fire along the fuse of time.*
Time passes. It flows. Or so they say. Great philosophers say this.
Fluids flow, but time flows only in a metaphorical sense. This is the sense in which future events somehow move constantly closer to our Now, while past events recede ever farther into the past, just like when a runner who approaches us, then passes us by, and then recedes. We all experience this flow, but only in the sense that we all experience optical illusions.
Physicists sometimes carelessly speak of time flowing when what they mean is that time has an arrow, a direction from the past to the future. In this sense time definitely does flow, but again this isn’t the sense of “flow” that philosophers are usually talking about.
In the sense of “flow” that too many philosophers do promote, I believe they are confusing time existing with time flowing. Here is why. Things change, so time exists. But that change doesn’t itself change; so, it’s a mistake to say the change “flows.” Let me explain this a little more. Time is what clocks measure. Time is a measure of change that puts dates on events, and tells us how long an event lasts, and says which events happen before which other events. That isn’t the same thing as the flow of time. When things change we say, “Time flows on,” or “Time stops for no one,” but these are inaccurate, poetic remarks. The changes are a sign of time existing, not time changing. When you experience change from eggs to omelets, or change from here to there, you are experiencing time itself, not a passage of time, nor a passage of the passage.
If you can place a date on an event and say it occurred, say, on Tuesday, then that same event doesn’t flow into Wednesday and then on into Thursday. It’s always an event that occurred last Tuesday. So, it is a mis-description of events to say they flow from the present into the past, yet that is what too many philosophers do say.
If time passes, what does it pass? Maybe you want to say it passes us. Hmm. Does it pass our childhood just as fast as it passes us now? Probably it passes at the same rate. OK, let’s assume it does pass at that rate. But what rate would that be? It would have to be a rate of one second per second. But that’s silly. One second divided by one second is the number one. That’s not a coherent rate.
I recommend saying the flow is subjectively real but not objectively real. The mistaken belief that time flows is due to our being misled by careless speech about time (“Time stops for no one”), but it is also due to some objective feature of our brains that makes us “feel” as if time is flowing. I suspect this objective feature is partly our having different perceptions at different times and partly our anticipating experiences before remembering those experiences.
Half the philosophers of time would accept my argument above; the other half believe the flow of time is necessary for “a literal and complete account of Everything That Is So,” to quote from last week’s posting by Professor Pyne. Half of us are mistaken. Which side of this fence are you on–the side that says time is dynamic and flows, or the side that says time is static and doesn’t flow?
Department of Philosophy
*George Santayana, in The Realms of Being.