Tuesday, February 5, 2013

An argument against the possibility of instantaneous causation

Instantaneous causation is causation where the cause and effect both occur at the same instant. It's a species of simultaneous causation, with the added condition that the events are instantaneous.

Suppose that instantaneous causation is possible. Then the following are compossible characters: the Judge, who instantaneously stamps death warrants, and the Executioner, who executes the person listed on the warrant in such a way that the very instant that the death warrant is stamped, the person is dead. Moreover, the Executioner takes no orders from dead people: she only executes people if the Judge was alive at the instant the warrant was stamped, and she executes no one else.

There is no metaphysical absurdity if the Judge stamps a warrant for your death—there is "merely" an injustice. But what if the Judge stamps a warrant for his own death?

Then, instantaneously, the Executioner executes the Judge. But then the Judge wasn't alive to stamp the warrant (and if he stamped it posthumously, then that doesn't count). But with no warrant stamped, the Executioner didn't do anything. And so the Judge both is and is not executed, which is absurd.

Now, we might conclude from this just that it's not possible for the Judge to stamp a warrant for his own death. And we could tell stories similar to banana-peel stories from the Grandfather Paradox: if the Judge were to go to stamp his own death warrant, he'd slip on a banana peel, or the stamp would be out of ink, or some other such thing would happen. But many philosophers are unsatisfied with such stories. It sure seems like it's no harder in principle (though it may be psychologically harder, though only if he knows it's his) for the Judge to stamp his own warrant than anyone else's.

It seems that a particularly good way to explain the impossibility of the setup, without any banana peels, is that instantaneous causation is not possible. In any case, people who think the Grandfather Paradox establishes the impossibility of time travel should think that this argument establishes the impossibility of instantaneous causation.

But what about the intuition one might have that instantaneous causation is possible? Here is a suggestion. Let the date of an event E be the temporal duration between the beginning of the universe and the event. (If the universe has no beginning, choose some other base for dates, with dates before it being negative.) Then our intuition that instantaneous causation is possible can have some justice done to it by saying that it is possible to have causation where the cause and effect have the same date, even though they are at different instants. These instants, then, have no duration between them. Thus, we could have the Judge and Executioner story work like this. There is a duration T (say, in seconds) from the beginning of the universe at which there is an instant, a, at which the Judge stamps his death warrant. And with no temporal gap, no duration in between, there is another instant b, at which the Judge is dead, also duration T after the beginning of the universe. (And between a and b there will be other instants, such as the instant when the Executioner sees the stamping and the instant when she initiates the causal process that kills the Judge. Quite possibly, in this story time is not dense.)

This does some justice to our intuition that there can be instantaneous causation. It's not quite instantaneous causation, but it's causation with no temporal extension, no temporal gap.

Acknowledgment: I got the warrant-stamping from Jon Kvanvig. It works better rhetorically than the instantaneous writing of the warrant that I initially had in mind.

16 comments:

Richard A. Christian said...


I’m not sure your argument works, let S= the Judge, F= the warrant, G= the executioner.
(1) If at an instant t S stamps F, then G executes S at t.
(2)If G executes S at t, then S is dead at t.
(3) If S is dead at t, then it is not the case that G executes S at t.
But you tell us to suppose the antecedent of (1), but that has the logical consequence that (4) If at an instant t S stamps F, then it is not the case that G executes S at t. And (1) and (4) can’t both be true. Does this undermine your argument? I take (3) from “Moreover, the Executioner takes no orders from dead people: she only executes people if the Judge was alive at the instant the warrant was stamped, and she executes no one else.”

Alexander R Pruss said...

Exactly, there is a contradiction. But if instantaneous causation is possible, the situation should be possible. After all, it's possible for the Judge to stamp someone else's warrant, so why not his own?

Richard A. Christian said...
This comment has been removed by the author.
Richard A. Christian said...

Can we use a similar argument for non-instantaneous causation?
(1) If at an instant t S stamps F, then G executes S one second after t.
(2)If G executes S one second after t, then S is dead one second after t.
(3) If S is dead one second after t, then it is not the case that G executes S one second after t. (since in my scenario she only executes people who are alive at exactly one second after t)
But if non-instantaneous causation is possible, the situation should be possible. After all, it's possible for the Judge to stamp someone else's warrant, so why not his own?
Just wondering how you would reply to that.
“if instantaneous causation is possible, the situation should be possible” why? The Judge can stamp his own warrant but the executioner wouldn’t be able to deliver because he is faced with an impossible task, I can image the executioner saying to the Judge “hey, I can’t execute you at T since you have to be alive at T to stamp the warrant, I can’t make it such that you’re dead and not dead at the same time”. Also, (2) and (3) entails that if the executioner executes the Judge at T, then she does not execute the Judge at T.It doesn't matter if the argument has these contradictions independent of (1)?

Alexander R Pruss said...

Your story still has instantaneous causation. To execute only people who aren't dead at t, one has to notice that the person isn't dead at t. And that noticing is a causal process presumably, which is instantaneous.

residentoftartarus said...

Alex,

I think this argument only applies to certain kinds of instantaneous causation. After all, I think we have at least one bona fide example of instantaneous causation in the EPR paradox, and it doesn't seem to me as if this argument would be applicable in that case.

Alexander R Pruss said...

Whether in EPR cases you have instantaneous causation will depend on what you think happens in those cases. You might think the causal story is this. I initiate an observation of the spin of one of the particles. This non-instantaneously causes two simultaneous effects: (1) my observing of the spin and (2) the collapse of the wavefunction (at both spatially isolated locations, of course). There is no instantaneous causation here.

Now you might think that one particle's acquiring of definite spin instantaneously causes the other particle's acquiring of definite spin. If so then you may have instantaneous causation. But it seems to me to be much more natural to think of your observation as interacting with a non-local reality, the entangled wavefunction.

There is still a possible instantaneous causation in quantum collapse, even apart from EPR, on the traditional interpretation. For on the traditional interpretation, the observation triggers collapse. But now it seems we have three simultaneous and instantaneous events:
1. The observing.
2. The collapse to a pure state.
3. The observing of the pure state.
And it seems that 1 causes 2 and 2 causes 3.

This could be true instantaneous causation. For there need be no observing prior to the observing of the pure state.

But it is very weird to think of 1 as causing 3. On plausible coarse-grained accounts of events, 1 and 3 are the very same event. My seeing right now is the same event as my seeing of this computer screen.

It seems preferable instead to take the sequence: There is some cause C of my observing. This cause then causes the collapse to a pure state. And the collapse to a pure state makes the observing be an observing of the pure state. All of these events might happen on the same date, but at different instants.

residentoftartarus said...

Alex,

Those are all interesting points...

Here's another possible scenario of "instantaneous causation" for you to consider: if you think the past is finite then it seems to me that the kalam cosmological argument (KCA) plausibly gives you an instance of instantaneous causation.

Alexander R Pruss said...

Why?

residentoftartarus said...

My understanding is that KCA wants to say that the temporal world was brought into being by some external cause. However, that cause (for obvious reasons) could scarcely have temporarily preceded the effect that is the temporal world. So, the cause must be simultaneous with the effect in this case.

Do you see a problem with this line of reasoning?

Alexander R Pruss said...

The cause could be outside of time. Probably, that's the best way to take it, no?

residentoftartarus said...

"The cause could be outside of time. Probably, that's the best way to take it, no?"

In light of your recent argument against instantaneous causation I suppose it might have to be an atemporal cause. :)

I am not sure why, but at some point I developed an allergy to the idea of an atemporal cause having a temporal effect. However, that's starting to look like rank prejudice right now.

Alexander R Pruss said...

I think a take in the spirit of Bill Craig would be that God exists in an undifferentiated moment that has infinite duration prior to creating. God at that moment then creates a universe-at-the-first-differentiated-moment. So there are two moments: God's undifferentiated eternally long moment and the first moment of creation.

I don't like this on theological grounds--it seems to make God change. Metaphysically, can a moment have duration? I don't know.

residentoftartarus said...

"I don't like this on theological grounds--it seems to make God change. Metaphysically, can a moment have duration? I don't know."

I don't either. It's deeply perplexing stuff.

David Gordon said...

A weakness of this example is that it depends for its force on the stipulation "the Executioner takes no orders from dead people: she only executes people if the Judge was alive at the instant the warrant was stamped, and she executes no one else."
The argument doesn't show that instantaneous causation is intrinsically metaphysically or physically impossible; instead, it only shows that instantaneous causation can't be combined with a particular legal arrangement.

Alexander R Pruss said...

Or one could suppose that there can't be uncaused events and there is nothing else that can cause the stamping.