Wednesday, October 21, 2020

More on the problem of short pains

Consider these two very plausible theses:

  1. Whether I have pain at time t does not depend on any future facts.

  2. There is a length of time δt such that you cannot have a pain lasting no more than δt, but you can have a pain lasting 4δt.

Now imagine that I feel a pain that lasts from t0 to t2 = t0 + 4δt. Let t1 = t0 + (1/2)δt. Suppose it is now t1. Then I am in pain. But now I claim that this counterfactual is true:

  1. Were it to be the case that I was to be annihilated at t0 + (3/4)δt, I wouldn’t have felt any pain now.

Why? For if I were so annihilated, my pain could only have lasted (3/4)δt, which is too short for a pain by (2).

But by (3), whether I feel pain now depends on whether I will shortly be annihilated, contrary to (1).

Hence, we need to reject one of (1) and (2).

It is hard to reject (2). After all, imagine the sequence of times: a second, a quarter second, a sixteenth of a second, …, 2−40 seconds. Clearly I can feel a pain that lasts a second. The last of these is less than a picosecond, and clearly I can’t feel a pain that short. So somewhere in that sequence I must reach a δt which is too short for a pain, but where 4δt isn’t too short for a pain.

I think denying (1) isn’t as bad as it may seem.

But perhaps a less counterintuitive move is to deny that phenomenal times and physical times are as closely correlated as they intuitively seem. Here is a possible story. Phenomenal times are discrete points while physical times are continuous (or discrete on a much finer timescale). You can feel a pain that is located at exactly one phenomenal time. The spacing between the phenomenal times corresponds to a fairly large (and non-uniform) spacing between physical times, say of the order of magnitude of a millisecond. So, you can feel a pain that is there one millisecond and gone the next, but you may feel it at exactly one point of phenomenal time.

As far as I can tell, it is not possible to run the annihilation argument while keeping careful track of the continuous physical and discrete phenomenal timelines. I guess this is a way of rejecting (2) by making it not make sense.

Here is a third way out of the argument. Imagine that what it is to have a pain at t is to have had some constitutive physical or spiritual process P have lasted some threshold period of time δt. On this view, before P lasted over a period of δt, there was no pain: pain only starts once P has lasted δt. We might now suppose that δt is something like a millisecond. Then it is possible to have a pain that lasts only a picosecond: for that, all we need is the underlying process P to have lasted δt plus a picosecond—and only the last picosecond of that process would have constituted a pain. But we no longer need to make the implausible claim that we can be aware of picosecond-scale stuff. For in paining, our awareness is the awareness of the underlying process P, and that process always needs to have taken something in the millisecond range for it to constitute a paining.

This way out of the argument also has the consequence that it is not possible to have a pain before completing the first δt of one’s existence. Pain is not a momentary property.

The third way out will not appeal to dualists who think phenomenal states are fundamental.


William said...

If a phenomenal experience need to have a certain duration to exist at all (a granularity in time), then, once the experience exists, it exists during every picosecond that it exists. But if its total duartion was only a picosecond it could not exist at all.

An ocean is never a single milliliter of water by itself, but once we have an ocean every milliliter is also ocean.

IanS said...

I’m not understanding (2). Isn’t pain by definition felt? If you don’t feel it, it’s not pain. A stimulus, or state of the body, that usually causes pain may fail to do so if its duration is too short. But then there would be no pain, not a pain too short to be felt. (Note that this differs from your third option. The stimulus or body state can cause a pain if it goes on long enough, but it does not constitute the pain.)

Alexander R Pruss said...


Right. "Cannot feel a pain" just means "Cannot have a pain" in (2).


That's the intuitive thing to say, but then we have to say that once we've had half the minimum granularity of pain, then whether we've HAD any pain depends on whether the other half of the granularity materializes. And that violates (1).

There is no similar paradox in the ocean, because there is no difficulty with saying that whether *this* milliliter of water is ocean depends on the *other* milliliters. But it is paradoxical to say that whether *this* bit of brain/mental function is pain depends on what will come *later*.

Alexander R Pruss said...

Re-reading (2), I can see that it lent itself to confusion as per Ian's remark, so I changed "feel" to "have".

William said...

Assume that for some reason (maybe a consequence of certain laws of nature?) a certain duration in time (Delta) of an input of some kind is part of what is needed for a human (H) to have a certain cognitive event (E) that properly expresses their powers of cognition.

So, Delta is part of the "recipe" for event E in H.

So, let us say that a situation generally leading to event E begins. Let's say that a clock then starts running, and if all other parts of our "recipe" for cognitive event E are in place, after Delta time elapses, event E will have occurred and (may then continue for longer than Delta).

Note, we said that Delta is part of the recipe for E! If we stop the H from existing one picosecond into the clock running, Delta is never part of our recipe, so we never make a proper cake E. So, event E never even occurs, and there was never any event E to start and stop in one picosecond.

But, you say, we could wait until event E occurs, then travel back in time and stop H after a picosecond. But we are thereby creating the "killing your grandfather before he sires your father" kind of paradox.

Alexander R Pruss said...


Suppose E is a pain.

When does the hurting begin? Right when the clock starts running or only after the elapse of Delta?

If the hurting begins right when the clock stops running, then you get the paradoxical claim that whether it hurts for the first picosecond depends on whether the process gets stopped after the picosecond.

But if the hurting begins only after Delta elapses, then it didn't hurt during the first picosecond, and hence it's false that E starts when the clock starts running. For it is a necessary truth that if E, a pain, occurs at t, then it hurts at t.

William said...

The hurting begins during Delta-time. Once the initial _duration_ is part of the pain event, we can then find the start and end of the pain, but only then.

Before the duration occurs, the start and end of the non-yet-existing pain are undefined. We only can find out when the pain began after there is the experience of the pain.

Yes, this means that the present depends on the past in this particular case.