Time Travel: A History (12 page)

He arrives at a conclusion: “The ego was himself. Self is self, an unproved and unprovable first statement, directly experienced.” Henri Bergson would have appreciated this story.

He thought of a way to state it: Ego is the point of consciousness, the latest term in a continuously expanding series along the line of memory duration….He would have to try to formulate it mathematically before he could trust it. Verbal language had such queer booby traps in it.

He accepts the fact (because he remembers) that his earlier selves had also felt themselves to be the one and only integrated and continuous being, Bob Wilson. But that must be an illusion. In a four-dimensional continuum each event is an absolute individual, with its own spacetime coordinates. “By sheer necessity he was forced to expand the principle of nonidentity—‘Nothing is identical with anything else, not even with itself’—to include the ego. The Bob Wilson of now is
not
the Bob Wilson he had been ten minutes ago. Each was a discrete section of a four-dimensional process.” All these Bobs—no more one and the same than the slices of bread in a loaf. And yet, they have continuity of memory, “a memory track that ran through all of them.” He recalls something about Descartes. If we know anything about philosophy we know this:
cogito ergo sum.
We all feel that. It is the defining illusion of
Homo sapiens.

As readers, how can we help but understand Bob as a unified self? We have lived with him through all the twists of his timeline. The self is the story he tells.

—

WE REACH
(and it won’t be the last time) the problem of free will. This was the second of the philosophical difficulties that Heinlein decided to explore as his narrative proceeded. Or perhaps I should say, found himself exploring, willy-nilly. He had no choice. When you send Bob back in time to meet his earlier self and relive an episode from his newer, wiser point of view, it is inevitable that Bob will ask:
Can’t I do it differently this time?

Then we loop again, and now Bob Three, older and wiser still, disagrees with Bob Two about what Bob One ought to do. He presumes that he, or they, have a choice. Will the earlier Bob defer to the superior wisdom of his later self? Hardly. He still needs to give one self a black eye and push the other self through the Time Gate.

The reader sees the whole picture—from above, so to speak—well before Bob does. Bob tries using the Time Gate as a window into spacetime, but the controls are hard to manage. Sometimes he sees, or senses, “flitting shadows which might be human beings.” We know they are his own shadows, flickering on the cave wall. Bobs one and all are striving to fulfill their own destiny. The paradox, if it is a paradox, is that they have to work so hard, even as they gradually realize that their looping travails are foreordained. There is no escape from the track they are on. As Bob hears himself reciting words he has already spoken, he tries feebly to rewrite the script. “You’re a free agent,” he tells himself. “You want to recite a nursery rhyme—go ahead and do it…and break this vicious circle.” Yet just at that moment he can’t think of a nursery rhyme. His lines have been written for him. He can’t get off the treadmill.

“But that’s impossible!” he cries. “You’re telling me that I did something because I was going to do something.”

“Well, didn’t you?” he calmly retorts. “You were there.”

Young Bob still doesn’t like it. “You would have me believe that causation can be completely circular.” And Old Bob, despite all his hard-won knowledge, never stops working to fulfill his destiny. He does not wait for his earlier selves to play their roles; he manipulates them urgently. The narrator says: “Everyone makes plans to provide for their future. He was about to provide for his past.” Taken all in all, this story is a snake pushing its own tail while musing about whether the effort is necessary.

The author, churning out stories on his manual typewriter to pay the bills in Southern California, trying to make his plots plausible and his characters convincing, has his own problem with free will. He makes his people into puppets, the strings flickering in and out of our sight. Their own view is foreshortened. Only the omniscient author, with his penciled diagrams, sees everything at once. We readers are caught up in the story, remembering the past, anticipating the future; we are mortals, for whom now means now.

It’s not easy to get past that, in reading stories or in living our lives. As Heinlein puts it, we must make “a strong and subtle intellectual effort to think other than in durational terms, to take an eternal viewpoint.” Free will cannot be easily dismissed, because we experience it directly. We make choices. No philosopher has yet sat down in a restaurant and told the waiter, “Just bring me whatever the universe has preordained.” Then again, Einstein said that he could “will” himself to light his pipe without feeling particularly free. He liked to quote Schopenhauer:
Der Mensch kann wohl tun, was er will; aber er kann nicht wollen, was er will.
Man can do what he will, but he cannot will what he wills.

The free will problem was a sleeping giant and, without particularly meaning to, Einstein and Minkowski had prodded it awake. How literally were their followers to take the space-time continuum—the “block universe,” fixed for eternity, with our blinkered three-dimensional consciousnesses moving through it? “Is the future all settled beforehand, and only waiting to be ‘pushed through’ into our three-dimensional ken?” asked Oliver Lodge, the British physicist and radio pioneer in 1920. “Is there no element of contingency? No free will?” He begged for a sort of modesty. “I am talking geometry, not theology, and it would be a stupid mistake to pretend to decide questions of high reality by aid of mere groping analogies and mathematical analysis….The human race has not been in existence very long; it began its scientific studies very recently; it is still scraping on the surface of things, the three-dimensional surface of things.” We may say the same, a century later.

—

PHILOSOPHERS DID NOT NEED
the space-time continuum to tell them that there were problems about free will. As soon as the rules of logic were added to the human tool kit, the ancients found themselves capable of constructing the most amusing puzzles. Human language switches between past and future with a simple change of tense, and this can trap the unwary.

“For what is and what has come about, then, it is necessary that affirmation, or negation, should be true or false,” Aristotle said. In other words, statements about the present and statements about the past are either true or false. Consider the proposition
There was a sea battle yesterday.
True or false. There is nothing in between. So it is natural to consider whether this applies to statements about the future.
There will be a sea battle tomorrow.
By Saturday this will be true or false, but must it be either true or false
now
? Put in terms of language and logic, these propositions look identical, so the same rules should apply. There will be a sea battle tomorrow. If it’s not true or false, what else is there?

Aristotle remained unconvinced. He carved out an exception for propositions about the future. Where the future is concerned, he felt logic needed room for another state of things: call it indeterminate, contingent, unfixed, unknown, up for grabs…The modern philosopher finds this clumsy.

By the weekend, there
will have been
a sea battle. Not every language has a future perfect progressive tense built in; when your language does, it tends to feel natural. Either there will have been a sea battle or there won’t. When the time comes, we’ll know which. It will seem
to have been
inevitable. In this way, language and logic tend to suggest an eternalist view, the Universe Rigid, the view that gained solidity with the arrival of clockwork physical laws as revealed by Newton and Laplace. The block-universe package was wrapped and sealed, seemingly, in the four-dimensional space-time continuum. The new physics profoundly influenced philosophers, whether they acknowledged it or not. It freed them from the common intuitive sensation that past and future are quite different. It freed philosophers, that is, while imprisoning the rest of us. “Past and future must be acknowledged to be as real as the present,” wrote Bertrand Russell in 1926, “and a certain emancipation from slavery to time is essential to philosophic thought.”
^*2
A fatalist says: Everything that happens had to happen. Q.E.D.

Donald C. Williams, a realist from California, picked up that thread at midcentury with a paper on “The Sea Fight Tomorrow.” His brand of realism was four-dimensional—fully modern, in other words. He asserted “the view of the world, or the manner of speaking about it” (a nice distinction, so easily forgotten),

which treats the totality of being, of facts, or of events as spread out eternally in the dimension of time as well as the dimension of space. Future events and past events are by no means present events, but in a clear and important sense they do exist, now and forever, as rounded and definite articles of the world’s furniture.

In the 1960s, the sea battle of tomorrow got a new life in the journals of philosophy. An argument raged over the logic of fatalism, and a milestone in the debate was the essay “Fatalism” by Richard Taylor, a metaphysician and beekeeper at Brown University. “A fatalist,” he wrote, “thinks of the future in the manner in which we all think of the past.” Fatalists take both past and future as given, and equally so. They may get this view from religion or, lately, from science:

Without bringing God into the picture, one might suppose that everything happens in accordance with invariable laws, that whatever happens in the world at any future time is the only thing that can then happen, given that certain other things were happening just before, and that these, in turn, are the only things that can happen at that time, given the total state of the world just before then, and so on, so that again, there is nothing left for us to do about it.

Taylor proposed to prove fatalism entirely by philosophical reasoning, “without recourse to any theology or physics.” He used symbolic logic, representing the various statements about the sea battle in terms of
P
and
P
′ and
Q
and
Q
′
.
All he needed were “certain presuppositions made almost universally in contemporary philosophy.” Something had to give: either fatalism or the rules of logic. A philosophy battle ensued. One of Taylor’s presuppositions was not as evident to everyone else: “that time is not by itself ‘efficacious’; that is, that the mere passage of time does not augment or diminish the capacities of anything.” In other words, time itself is not an agent of change; more of an innocent bystander. Time doesn’t do anything. (“What is a
mere
passage of time” retorted one of his critics. “Could time possibly pass without something, somewhere, changing—without the tick of a clock, the movement of a planet, the twitch of a muscle, or the sight of a flash?”)

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.