Thursday, July 24, 2014

Are you a determinist? Here's how you can tell

Would you say, with respect to any decision that you have made, that given the actual past, you could have done otherwise than what you did? Determinists may agree with the statement "I could have done otherwise," but what they mean is that if the past had been different, the act would have been different.  Libertarians say that even given the actual past, they could have done otherwise from what they did.

12 comments:

John Mitchell said...

Dr . Reppert

It might be interesting to discuss the fact that important progress has been made concerning Van Inwagen's consequence argument by Alexander Pruss.
Pruss was, by adopting two different notions of unavoidability, able to prove a version of the improved beta-inference, that previously was only thought to be intuitive.

The original paper by Pruss can be found here (https://bearspace.baylor.edu/Alexander_Pruss/www/papers/consequence.pdf)

An elaborate version of the argument, which is probably easier to understand can be found here (http://philosophycommons.typepad.com/files/0-elaboration-on-prusss-result-3.pdf)

Though a few questions remain, it now seems that the consequence argument is quite strong and compatibilism has a huge problem to face.

jdhuey said...

Libertarians say that even given the actual past, they could have done otherwise from what they did.

I think that this entire thought experiment falls into the category that our Logical Positivists friends would call 'meaningless noise'. Or rather from a strictly naturalist perspective it is meaningless. If you posit a god watching the action from outside of time or posit the person having a non-material mind that can remember things even after the brain state reverts to the pre-decision condition, only then does the experiment mean anything.

Consider, from a naturalistic perspective what it would mean to travel back in time. If it means that every sub-atomic particle is in exactly the same configuration for everything except the time traveler, then we have the situation that was mention in the OP - things really are not exactly the same and so any alternate decision making doesn't really say anything about free will/determinism.

If it means that every sub-atomic particle is in exactly the same configuration for everything including the time traveler, (and bearing in mind that there is no outside observer) then it is impossible to know if the decision was different or not. Perhaps there was Libertarian Freewill (tm) or the atoms of the person followed the exact same world-lines as before with exactly the same outcome. Either way it is unknowable - under naturalism there can be no observer to tell.

Frankly, I think that time travel into the past is just not possible, at least in any of the conventional literary configurations - the past is locked in place.

Nor do I think that it is really meaningful to say that future is completely determined (a la Laplace). Note that Laplace had to invoke a magical entity to perform all the necessary calculations. To my mind, if you have to rely on a demon to do something then it is probably impossible to do that thing. When we use mathematics and science to make predictions of the future it is never a complete set of calculations. We have to use approximations and truncated sets of data. For example, when we calculate the position of the planets we ignore the gravity impacts of distant stars - they are there but they are so small we can ignore them for practical purposes. If we could attempt to perform the complete set of calculations, quantum mechanical and relativistic factors would limit calculation speeds: we could never get an answer before it actually happened in reality. Reality doesn't need the time to perform all those calculations, it just responds to what is there. We could never beat the universe at the calculations, we could, at best, tie but then what would be the point?

So, the past is locked, and the future is unwritten and the discussion of Freewill vs. Determinism is just meaningless noise.

Victor Reppert said...

But doesn't that involve using the verification principle, which has all sorts of problems (starting with blatant self-referential incoherence?) Couldn't something be true without being verifiable?

grodrigues said...

@jdhuey:

"I think that this entire thought experiment falls into the category that our Logical Positivists friends would call 'meaningless noise'."

Counterfactual questions are "meaningless"? Really? You better tell that to *naturalist* philosophers who give an account of *natural laws* in terms of counterfactuals.

"Consider, from a naturalistic perspective what it would mean to travel back in time."

Travelling back in time, its possibility or impossibility, has nothing to do with the issue (full disclosure: I think the way Victor has framed the issue is not the correct one). You are simply misunderstanding the problem.

"Nor do I think that it is really meaningful to say that future is completely determined (a la Laplace). Note that Laplace had to invoke a magical entity to perform all the necessary calculations."

Of course it is meaningful. Whether any one can make the computations, or even whether one has to invoke a computational imp is irrelevant. What is relevant is that the future is univocally determined by the past: once the state of the system is fixed at t_0, its evolution is completely deterministic and determinate, irrespective of whether there is anyone out there that can perform the calculations or not.

jdhuey said...

Counterfactual questions are "meaningless"? Really?

I don't think that I said or implied that counterfactual questions are meaningless. My contention is that using the idea of time travel as a test for or as a description of freewill/determinism is meaningless under the assumption of naturalism.

jdhuey said...
This comment has been removed by the author.
jdhuey said...

What is relevant is that the future is univocally determined by the past: once the state of the system is fixed at t_0, its evolution is completely deterministic and determinate, irrespective of whether there is anyone out there that can perform the calculations or not.

Ok. Let us play a little counter factual thought experiment. Ahura Mazda manifests himself to you and hands you a small box that has a toggle switch on top. He informs you that whenever the switch is in one position the universe is completely deterministic but when it is in the other position the universe is not completely deterministic. There are no markings or indicators on the box to tell you which position is which. Now your task is to set up any test conditions you want such that you can figure out which state the universe is in. In other words, what is it that you expect to see or feel that is different when you throw the switch.

jdhuey said...

"...the future is univocally determined by the past: once the state of the system is fixed at t_0, ..."

We need to be very careful in using the concept of t_0 with respect to the Universe: from relativity we know that there is no such thing as a universal time frame. This doesn't preclude determinism by itself, after all Einstein adhered to the idea of a deterministic Universe, but is does mean you have to be very careful in formulating what you mean.

grodrigues said...

@jdhuey:

"My contention is that using the idea of time travel as a test for or as a description of freewill/determinism is meaningless under the assumption of naturalism."

Has anybody used the idea of time travel as "as a test for or as a description of freewill/determinism"? I mean, besides you. The issue of Free Will touched upon in the OP has to do with PAP, counterfactuals, etc. and nothing to do with time travel. Absolutely nothing. You are simply misunderstanding the problem.

"Now your task is to set up any test conditions you want such that you can figure out which state the universe is in. In other words, what is it that you expect to see or feel that is different when you throw the switch."

I do not know what is the point of this test question, neither do I know how I am supposed to answer it. I did not set out to defend Free Will in my comment, just in pointing out the mistakes and misconceptions.

"We need to be very careful in using the concept of t_0 with respect to the Universe: from relativity we know that there is no such thing as a universal time frame."

Yes, we need to very careful; especially in talking about what one quite obviously ignorant of. General relativity is a classical field theory, and like any classical field theory the future is unequivocally determined by the past. This is a standard fact about differential equations, in the case of GR, an over-determined system of non-linear partial differential equations, so that the "state of the system at t_0" must be interpreted in a different way, e.g. fixed data on a space-like hypersurface, but everything goes through much the same. The fact, which is indeed a fact, that there is no global reference frame, that is, the space-time manifold is not isomorphic (in a certain category) to a product M x R, is completely irrelevant.

jdhuey said...

"Has anybody used the idea of time travel as "as a test for or as a description of freewill/determinism"? I mean, besides you."

I don't think anyone has but I think that it helps to clarify my point about this question from the OP:

'Would you say...given the actual past, you could have done otherwise than what you did?'

And my point is that one shouldn't even attempt to answer the question because even though it sounds like a reasonable valid question, it is in reality meaningless. I am completely unaware of anyone that has devised a way to see if a "Yes" answer is correct or if a "No" answer is correct. If you know of such a test please share. If such a test existed we could resolve the whole Free will/ Determinism question once and for all.

"I do not know what is the point of this test question,..."

The point of the test question is that if you can detect a real world distinction between the toggle switch positions then you have figured out a way to give a real answer Victor's question. It is my contention that no such test exists, which means that there is no actual difference between Freewill and Determinism. "A difference that makes no difference is no difference." And that means when a Libertarian (in the sense that Victor use the term) says they could have done otherwise from what they did, they are just making meaningless noise.






jdhuey said...

But doesn't that involve using the verification principle, which has all sorts of problems (starting with blatant self-referential incoherence?)
Victor,
Very good question. I think that if our intent was to build a complete and self-consistent philosophical system like the Logical Positivists tried to do, then we would indeed flounder on using the verification principle. However, my intent is much more modest: I just want to avoid accepting erronous or perhaps nonsensical proposistions. So, with that modest goal, the verification principle shouldn't be thought of as a foundational building block of a philosophical edifice. Rather, it is simply a tool, that helps to achieve a design goal: it is a filter that screens out undecidable questions.
"Couldn't something be true without being verifiable?"
This is one of those undecidable questions that should be screened out. If we can not verifiy (or get some type of indication of) somethings truth value then we have no way to even guess if that something is true or false. To say that something is not verifiable is that same as saying that it is irrelevant to the functioning of the real world. If it is true or false the world will operate in exactly the same way.

grodrigues said...

@jdhuey:

"And my point is that one shouldn't even attempt to answer the question because even though it sounds like a reasonable valid question, it is in reality meaningless."

And I have already explained why you are wrong; or, to borrow your own words, you are "just making meaningless noise."