Is the Passage of Time Real or Just an Illusion?
One of the main targets of Sean Carroll's new book, The Big Picture: On the Origins of Life, Meaning, and the Universe Itself (Dutton, 2016), is causality. Like many naturalists, he sees where the causal chain leads—a series of contingent causes demands a necessary First Cause. So if you want to avoid a First Cause, you must get rid of causality.
As discussed in an earlier post, Carroll's first attempt appealed to the conservation of momentum. It wasn't clear how that principle undermines causality, and Carroll showed many other signs of confusion.
Later in the book, he tries to refute causality again, but this time using a controversial theory of time, known as the "B-theory" or "tenseless" theory of time (Carroll never uses these terms, but they indeed describe his view.)
Philosophers distinguish between two major theories of time, and it's worth noting that the philosophical community is generally split between the positions.
First is the A-theory, which is the common-sensical view that the passage of time is a real feature of the world, and not merely some mind-dependent phenomenon. This position holds that time is tensed, which means the past, present, and future are objectively real—in other words, tense is real (i.e., we can accurately use the "past tense"). If you asked the average person on the street how they understand time, they would likely give an A-theory description.
B-theorists, on the other hand, hold that the flow of time is an illusion, that time is tenseless such that past, present, and future are just illusions of human consciousness. This would imply that temporal becoming (e.g., growing older) is not an objective feature of reality.
If the B-theory were true, causality would indeed become trickier. Some would say that on the B-theory, causality would disappear altogether, while others more modestly claim it still exists, just in a more constricted, nuanced fashion. Either way, if your goal is to disprove causality, the B-theory is your best bet since causality is an obvious feature of reality on the A-theory, but not so on the B-theory.
So other than trying to avoid the conclusion of a First Cause, why does Sean Carroll promote the B-theory of time? Unfortunately, he doesn't tell us in his book. He doesn't acknowledge the two competing views, nor the present debate over which is true. He just asserts the B-theory as true, stating without elaboration, "In reality, both directions of time are created equal" (55), which is only true on the B-theory of time.
Carroll doesn't engage serious scholars who challenge the B-theory of time, nor any arguments for the A-theory. (William Lane Craig, one of the most prominent A-theory proponents, has written at least four scholarly books on the topic. Presumably, since Carroll debated Craig on topics that broached the philosophy of time, he was familiar with those works. But he never acknowledges them in The Big Picture.)
In his book, Carroll merely assumes the B-theory of time is true, without evidence or argument, and then uses that in his quest to show that causality is not a real feature of fundamental reality.
As in his earlier chapters on causality and determinism, Carroll does waffle a bit in this section. While he doesn't think causality is fundamentally real, he also sees the need for causal language. He isn't willing to go as far as Bertrand Russell, who said, "The law of causality, I believe, like much that passes muster among philosophers, is a relic of a bygone age." Carroll believes such a view is "too extreme" since it contradicts our everyday experience of causes. "After all," Carroll writes, "it would be hard to get through the day without appealing to causes at all" (64).
Which is where his "poetic naturalism" comes in. Although Carroll doesn't think causality is a real feature of fundamental reality (since he holds the B-theory of time), he does think it's a useful concept to describe our everyday world, and thus should be retained, at least in the domain of our everyday experience.
But once again, as is the case with other applications of his "poetic naturalism," we're left with a contradiction. Causality is either a real feature of reality, or it's not. What Carroll essentially proposes is that at a fundamental level it's not, because the B-theory is true and thus the passage of time is illusory.
Yet if that's the case, it wouldn't be accurate to use causal language in any situation. At best, such language would create a useful fiction; at worst it would be delusory.
In the next post we'll explore Sean Carroll's take on Bayes’ Theorem of probability.
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