Time Travel. A History

Two decades later, at Amherst College, an undergraduate philosophy student named David Foster Wallace, himself the son of a professional philosopher, grew obsessed with this nettlesome debate, “the famous and infamous Taylor argument.” He wrote to a friend, “If you read the Taylor literature, it’s really ulcer-city.” He plunged in nonetheless. His obsession became his honors thesis, which might have taken its title from the imaginary Bob Wilson’s “An Investigation into Certain Mathematical Aspects of a Rigor of Metaphysics.” He drew diagrams to sort out “world-situations” and their possible “daughters” and “mothers.” Yet as much as the formal, axiomatic side of philosophy appealed to Wallace—gave him continual pleasure and satisfaction—he never accepted it without reservation. The limits of logic and the limits of language remained live issues for him.

Words represent things but the words are not the things. We know that but we can forget. Fatalism is a philosophy built out of words, and ultimately its conclusions apply to words—not necessarily to reality. When Taylor leaves work, he summons the elevator just like the rest of us, by pressing the button. He does not think to himself, Don’t worry, the elevator will follow its destiny. He may think, When I press the elevator button, it is not a free choice—it was fated. But he still goes to the trouble of doing it. He doesn’t just stand there and wait.

Of course, Taylor himself knew this full well. He can’t be refuted so easily.

A fatalist—if there is any such—thinks he cannot do anything about the future. He thinks it is not up to him what is going to happen next year, tomorrow, or the very next moment. He thinks that even his own behavior is not in the least within his power, any more than the motions of the heavenly bodies, the events of remote history, or the political developments in China. It would, accordingly, be pointless for him to deliberate about what he is going to do, for a man deliberates only about such things as he believes are within his power to do.

He added, “And we are not, in fact, ever tempted to deliberate about what we have done and left undone.”

I wonder whether Taylor had read much time-travel fiction or even, for that matter, whether he lived in the world I live in, where regret is not unknown and people do sometimes speculate about what might have been. Everywhere we look, people are pressing elevator buttons, turning doorknobs, hailing taxicabs, lifting sustenance to their lips, and begging their lovers’ favor. We act as though the future is, if not in our control, not yet settled. Nonetheless, Taylor dismissed our “subjective feelings.” We would suffer illusions of free will, because, by happenstance, we tend to know less about the future than about the past.

Many philosophers, in the years that followed, had tried to refute Taylor, but his logic proved amazingly robust. Wallace wanted to defend the common intuition “that persons as agents are capable of influencing the course of events in their world.” He plunged into the depths of symbolic logic. “Since obviously under any analysis I have to do either O or O′ (since O′ is not-O), that is, since (O ∨ O′); and since by (I-4) it is either not possible that I do O or not possible that I do O′, (∼◊O ∨ ∼◊O′), which is equivalent to (∼◊∼∼O ∨ ∼◊∼O), which is equivalent to (∼O ∨ O), we are left with (O ∨ ∼O); so that it is necessary that whatever I do, O or O′, I do necessarily, and cannot do otherwise” is a sample sentence. (“Obviously”!) In the end he defeated Taylor’s fatalism by stepping back and viewing not only the chains of symbols but also the levels of symbolic representation—viewing them, as it were, from above. Wallace distinguished between the realm of semantics and the realm of metaphysics. Considered strictly as words, he argued, Taylor’s logic may be internally valid, but it’s cheating to leap from semantic premises and arguments to a metaphysical conclusion.

“Taylor’s claim was never really that fatalism was actually ‘true,’ only that it was forced upon us by proof from certain basic logical and semantic principles,” he concluded. “If Taylor and the fatalists want to force upon us a metaphysical conclusion, they must do metaphysics, not semantics.” In metaphysics we find the doctrine of determinism—we’ve seen this before, given its perfect expression by Laplace. Determinism is this (per Wallace):

the idea that, given a precise and total state of affairs at one instant, and the physical laws that govern the causal relations between states of affairs, there is one and only one possible state of affairs that could obtain at the next instant.