Does the present exist?

Answer

Dear Stefan,

What a beautiful question. Last semester I taught a course on “Philosophy of time”. There were a number of possible answers to your question. I briefly list the four most important visions here, from more to less intuitive:

1. Only the present exists, past and future are an illusion. This position is called presentism. (This assumes that the present does not overlap with past and future, so is not the “intersection” as you say. Mathematically, we could do this by representing past and future through open sets.) This view agrees well with our experience: after all, we cannot see, feel or point to the past and the future.
2. The present and the past exist, but the future does not. This is called possibilism and ties in with the intuitive idea that the past is fixed, but the future is not yet. This view is sometimes also called a growing block universe, but I can explain what a block universe is better in the next step.
3. Past, present and future exist and are equally real. This is called eternalism and this view has gained importance after the development of the special theory of relativity by Einstein. Einstein’s theory shows that simultaneity is relative (depends on the observer’s state of motion): so there is no universal ‘now’ and this puts pressure on the idea that only the present is real (presentism). We can imagine space and time together as a four-dimensional whole. This is sometimes also referred to as the block universe. The special theory of relativity is a deterministic theory: the future is fixed, but we just don’t know it yet. (To what extent this is compatible with another fundamental theory of physics, namely quantum mechanics, is not entirely clear, hence the current state of science is not sufficient to rule out options 1 and 2.)
4. Time is an illusion (including the vision of Parmenides and Zeno): something does exist, but that which exists is itself timeless. Time is therefore an illusion and also the division past/present/future, but that does not mean nothing exists. Here too, there are scientific theories that fit in well: in quantum gravity theory, for example, there are models in which time is an emergent phenomenon. That is, time itself could arise from a timeless theory!

I would also like to point out that the realism debate in the philosophy of science is mainly about the question of which objects really exist. (Some examples: Does a table exist? A planet? An electron? And how do we know?) The question you ask, “Does the present exist?” is of a different nature, and yet your train of thought suggests that there is nothing would exist (i.e. no objects either). Within philosophy of time this issue is looked at in a different way:

• On the one hand, there is the question of whether or not time really exists. If time is an illusion (option 4 above), it does not follow that nothing exists. For example, the question arises as to why we have this illusion.
• On the other hand, there is the question of how objects continue to exist over time. There are also different answers to this, but that would lead me too far here.

Regards,
Sylvia Wenmackers