Let's suppose that you slip and spill a cup of coffee all over yourself right now, and that you also spilled a similar cup last month, and that you will again next year. Of these three events, the present spill is so much more vivid, isn't it? That is a principal reason why metaphysicians called presentists say that if anything is physically real, then it exists now. Advocates of the growing-past theory of metaphysics argue that, although that past cup of coffee is less vivid, nevertheless it is just as real. It simply is not present. The past grows, they say, by accumulating more objects and events. Those past cups of coffee are real because they once were present. Future cups are unreal, though, because they have never been present.
Opposed to both presentism and the growing-past theory, the metaphysical theory of eternalism implies that all future cups of coffee are just as real as the present and past ones. Presentism is the metaphysical position that is closest to common sense. It is the position that was adopted by most philosophers before the confirmation of the theory of relativity, yet now eternalism is the most popular position.
The debate is about physical time, the time that clocks are designed to measure. It is not about psychological time, the awareness of physical time.
Opponents of presentism complain that it cannot account for causation, for April showers causing May flowers. Can there be causation without both the cause and the effect being real?
Regarding eternalism and its acceptance now of the reality of the future, the philosopher William James famously remarked that the future is so unreal that even God cannot anticipate it. The eternalist counters that not being anticipated doesn't imply not being real.
The eternalists' primary argument is that the distinctions among past, present, and future are not reflected in the laws of physics and so are merely subjective, depending on whose perspective is being assumed. Regarding these perspectives, your birth is in your past, but it is in George Washington's future. So, at least some of George Washington's future is real. If some, why not all?
The cup of coffee being handed to you here is no less real than a cup of coffee far away in Antarctica. Distance is not a mark of unreality. Similarly, a temporally distant cup of coffee is no less real than the cup you are having now, says the eternalist. Temporal distance is not a mark of unreality. The concepts of being here, being there, being present, being past, and being future are all subjective because they depend for their reference upon the situation of the person using the concept. The concepts do not signify any difference in what is objectively real.
Don't we all fear impending doom? But according to presentism and the growing-block theory, it should be irrational to have this fear since the doom is known not to be real. The eternalist defends our rationality.
A key feature of eternalism is that events are fundamental; three-dimensional objects are not. One interesting implication of this is that fundamentally you as a child, you as a teenager, you as an adult, and you (hopefully) as a very old person are not periods of the same 3-dimensional person but rather are different parts of the same 4-dimensional person, the real you. In ordinary discourse, it is usually helpful to think of persons and coffee cups as 3-dimensional, but fundamentally they are not. They are temporally extended events.
What propels philosophers and scientists toward eternalism is their belief that it is implied by the best understanding of physics. If we trust the physics, we should trust its metaphysical implications, they would say. Reality is not what it seems. Einstein adopted this position when he said, after the confirmation of his relativity theory:
It appears therefore more natural to think of physical reality as a four-dimensional existence, instead of, as hitherto, the evolution of a three-dimensional existence.
In criticism of both presentism and the growing-past theory, the eternalist asks, "Whose present is the real present?" If my present and your present are different, could one be real and the other unreal? Surely not. Now consider the implication of what you just agreed to. Relativity theory implies that which set of events counts as the present is relative to the observer's reference frame. If I move fast relative to you, then a distant event on Jupiter can be present in your frame and still five minutes in the future in my frame. These last remarks radically violate common sense. So much the worse for common sense, Einstein would say; common sense is too often the faulty product of limited experience. If the presentist and the advocate of the growing-past theory imply that the Jupiter event is not real for me, being in my future, doesn't this imply there is a problem with presentism and the growing-past theories?
These are the eternalists' main reasons for their eternalism. Presentists and advocates of the growing past have heard the reasons, yet they do not crawl away into metaphysical obscurity.
One counterargument to eternalism is from H. A. Lorentz who said that merely because relativity theory implies that any reference frame is legitimate and that nobody's present is better than anyone else's, the theory could be mistaken. Somebody's frame might still be the privileged one. Scientific theories have their limits. The philosopher A. N. Prior added that perhaps Einstein's theory shows only that we cannot know which distant event on Jupiter is simultaneous with one of our present events.
Opponents of eternalism often complain that Einstein's block of past, present, and future events is too static. It just sits there. Yet change is very real. It is the essence of time. So, there is clearly something lacking in the eternalists' block perspective, and it should not be our guide on important metaphysical issues. In response, one eternalist said, "What? Do you want the block to wiggle?"
Sacramento State University