Who are you going to believe, me or your lying eyes?
—Chico Marx
Parmenides, one of the most important ancient thinkers, argued that change is impossible. It is the classic instance of these smart people saying something dumb. On what possible grounds could one deny the thing we see most?
“Something,” Parmenides begins, “cannot be both true and false.” Sure, Parmenides, that is obviously correct. “Yet,” he continues, “if change is possible then something no longer is as it was.” Sure, we know what the word “change” means. “So, to say that the thing is that way was true but now is false.” For a philosopher, Parmenides, you seem to say only the annoyingly obvious. “But,” he says with an obnoxious grin, “then to say ‘The thing has the property x’ was both true and false. But you agreed that something cannot be both true and false. So, change is impossible.”
Hold on there. I am not saying it is true and false. I am saying it was true and now is false. “Oh,” Parmenides, replies, “so, you are saying that time is real?” Parmenides turns to his student Zeno and says, “Your turn.”
Zeno of Elea gave the ancient world some of its most famous puzzles designed to support the Parmenidean axiom that change is impossible. Consider the paradox of the arrow. An archer launches an arrow. At any moment in time, the arrow is at a single position. This means that at that moment, the arrow is perfectly still. The entire flight of the arrow is comprised of nothing but individual moments. At each of these moments, the arrow is completely fixed, frozen, stationary. Yet, the time period is just the sum of these moments. If something is still at every moment, then it is always still. The arrow is still at every moment, hence the arrow does not move.
And so it is for the hands of the clock, for the Sun, for anything else you want to use to “tell time.” Without motion, there is no passing of time. Time is an illusion.
We might, like some of the ancients, point to the world. But, but, but…look! You see change. You can read your watch. I can see time flowing. To which Zeno and Parmenides would quote the great Chico Marx, “Who you going to believe, me or your lying eyes?”
A-time and B-time
John McTaggart Ellis McTaggart was an early 20th-century British philosopher who wanted to be the modern Zeno. For his own philosophical purposes, he too wanted to prove that time did not exist. Like Zeno, he would show that the assumption of the existence of time leads to a contradiction. Since contradictions must be false, the assumption therefore must also be false.
McTaggart begins by asserting that there are two different pictures of time: A-time and B-time. Both he says are true, yet they are mutually exclusive, contradictory.
A-time is comprised of three different regions. There is the past, the present, and the future and they are completely different from each other. The past is fixed. What happened in the past happened. It cannot be changed, it cannot be experienced, but it can be remembered. The present is what we experience. It is the now. It is what is happening. The future is the set of all moments that have not yet happened. It is open. It could develop in any number of possible ways. It cannot be experienced or remembered.
We, as metaphysical beings are stuck in the present. We are fixed in the now. Time flows past us and we experience it in its movement. We are like the slider on a zipper the open teeth of time in the future hit us and as they recede past become fixed. But unlike the slider of a zipper, we are not the thing moving. We are stuck in the now, as the teeth of time interlock as they move past us. We are stuck in time, like Zeno’s arrow, and time, as Isaac Newton famously wrote, “Of itself, and from its own nature, flows equably without relation to anything external.”
McTaggart’s notion of B-time is different. B-time, or block time as philosophers sometimes call it, does not move. It is fixed and unchanging. There is no difference between past, present, and future. Time is as it always was and the events of any time are the same as they ever were and will always be. B-time does not flow.
It only seems to because of us. We are the ones moving. We move through time. We experience the events embedded within time and as we do we form memories of our experiences. It is not that the past is fixed and the future is open, it is that we have experienced the past and not yet lived through the future. It is our mind that differentiates the parts of time, not time itself. The flowing of time is just a projection.
Think of watching a movie on a DVD or, for those of you who are old school, VHS. Maybe it is a murder mystery. Halfway through, the parts of the film you have already seen—the dastardly deed and the initial introduction of the characters—, the part you are now viewing—the detective starting to put the pieces together and trying to figure out what is a real clue and what is a red herring—, and the parts that are coming—the big plot twist and the solution, all of them are exactly same, just magnetic coding on the disc or tape. All of the scenes from start to finish are already there. You just haven’t seen them yet. It is you, the viewer, who are going through the movie. You may not know how it ends, but the end is every bit as fixed as the opening scene. History is fixed, you are the one moving through it.
Timeout for Time
So, does time flow or doesn’t it? Is it fixed or are we? McTaggart thought that A-time and B-time had to both be true. But, he also argued, they can’t both be true. So, he concluded, that time does not exist because time creates a paradox.
Today, few philosophers agree with McTaggart’s conclusion because they reject the claim that A-time and B-time must both be the case. But philosophers and physicists agree that these two categories are both possible, but not necessary. Time surely must be one of them, but not both. The question then is, which one is it? Is real time A-time or B-time?
A-time is the common sense view. It feels right. But more importantly, so much of how we relate to the world seems to rely on it. Think about ethics. If time is simply a set of unchangeable events, can anyone be held responsible for what they do? You are only condemned or celebrated for acts you chose and the precondition for having a choice is that things could have been otherwise. We want to believe we have free will, but that requires an open future of the sort only available in A-time.
But some very smart thinkers have contended that other commitments might force us into B-time. Gottfried Leibniz, for example, contended that an all-perfect God would have to create the best of all possible worlds. God exists outside of time and in choosing what universe to create would have done so knowing the entire history of the universe selected. Before Creation, God would scroll through the infinite set of shows to stream on the Divine version of Netflix, would know what happened in every possible one, and would click play on only the single possible universe that was the best one of the bunch. As such, an all-knowing, all-loving, all-powerful Creator requires there to be B-time.
Albert Einstein also championed B-time but for very different reasons. The laws of nature, he contended, have to be deterministic. If you tell me the true laws and the state of the universe at any one moment, then I should be able to predict or retrodict the rest of reality.
That, of course, is why he had such problems with quantum mechanics. “God does not play dice with the universe,” he argued. In other words, the future cannot be open as A-time would have it. But is it? Maybe we’ll tell tomorrow…if tomorrow is actually real…