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Philosophy/Changing the future?


QUESTION: My question concerns determinism. There is a popular notion that we cannot predict the future because we can change it, and make our predictions untrue.

"Back to the Future" is a movie that illustrates the idea of going back into the past and changing the future, for example, something I believe is not possible.

For my part I am a determinist, therefore I do not subscribe to this view, however is it possible to come up with a scenario that will illustrate the error of the popular notion?

I think "eternalism" is the concept I am thinking of.

All mechanical systems are deterministic. Computer systems are also deterministic. Suppose one was to create a robot and place it in a large room with mechanical devices that operate in a pre-programmed manner - a series of doors for example, leading to different partitioned spaces.

Now will the robot be able to predict his own passage in the deterministic playground, and if so, does it not invalidate the assumption that I stated in the beginning?

ANSWER: Sorry to have delayed the answer so long. A combination of a death in the family, health issues, and a disk crash.


There is a huge literature on determinism. The "hardest" of the hard determinist positions is that of the French astronomer Laplace: if we knew the initial positions and speeds of all the particles in the universe, we could predict all future events exactly. Which means that it was determined from the beginning of the universe that you would ask this question, and start with the phrase, "My question concerns determinism..."

On this view, there is no paradox, because we cannot change the future, even if we think we can. Whatever changes we make are determined, therefore their effects are determined, so the idea that anything at all can be changed is wrong.

Being able to predict one's own actions and being able to change them are two entirely different things. On the hardest hard determinist view, the robot was determined, from the beginning of time, and to do (or not do) something that validated, or invalidated, that prediction. We are not always determined to be right in what we predict, something we can be determined to be wrong. If one wants to call the failure of a prediction of this sort a change in the future, fine, but it seems an awfully long stretch of "change" and "future."

Hard determinism leaves no room for thought, so philosophers who are not determinists bug the philosophers who are about why they even bother; the determinist philosophers reply that it's because they were determined to do so.

At least one serious physicist, Julian Barbour, endorses eternalism, because he believes it vastly simplifies physics and gets rid of the friction between general relativity and quantum gravity.

My own view is that either our view of knowledge is completely wrong, or determinism is false. Given what we generally mean by "knowledge", we can know that we are not determined, therefore free, but if we are determined, we could never know that. And if we could never know that, there is no way to assert that determinism is true. So our only option is to assume that we are free.

Hope this helps.



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QUESTION: Sorry to to hear about your loss. I was wondering what was hapenning to the answer, thanks for taking the time to answer.

You seem to say that foreknowledge precludes choice.  I am not so sure:

Consider shooting an arrow at a target. You choose to hit the bulls eye. Suppose you actually hit the bulls eye because you are 1 mm away from the target. Suppose you were to go into the future and see the arrow stuck to the bulls eye. Then you come back to the present and know that the arrow will hit the bulls eye.

Here is the key: knowing the future, can you still choose to point the arrow at the bulls eye and shoot? Of course you can. Therefore foreknowledge does not preclude choice.

Perhaps we live in an universe in which our choices are identical with the predetermined future.

I think there is much more here than meets the eye. If we were to predict an asteriod crashing into the moon and had no way to change that event, then what?

ANSWER: There is indeed more than meets the eye. As I said, there is a HUGE literature on determinism.

In a "hard" determined universe, foreknowledge does not preclude choice, but all choices are determined, and, non-determinists would say, not choices at all. In such a universe, all choices would be consistent with the predetermined future. So would everything else.

You sort of want to have your cake and eat it too. In a hard-deterministic universe, everything that will ever happen is fully and unalterably determined the moment the universe began. We can do what feels like making choices, but both the choices and their outcomes cannot vary.

Choices which have no effect, same thing -- it is predetermined that the choice will have no effect.

Many, but not all, modern philosophers think that science cannot cash the check that Laplace wrote. Phenomena such as determinism and emergent properties suggest that the universe cannot be deterministic in the Laplace sense, but indeterminacy does not necessarily mean that we can make effectual choices.

Hope this helps.



---------- FOLLOW-UP ----------

QUESTION: This is very interesting. Yes I will be delving into the literature to see what has been said about this.

"We can do what feels like making choices, but both the choices and their outcomes cannot vary."

This is really the heart of the matter for me. The act of a human making a choice, seeing, reasoning, thinking, calling up memories (all in order to decide for example between vanilla and bubble gum ice cream ) is a psychological and physiological process that takes place independent of what happens. In other words "feeling" like making a choice and making a choice are identical on the human level.

However I understand what you say, in terms of ultimately the choice of being able to steer your ship in whatever direction you want, without the limit of having to end up at some future destination, whether pre-determined or even post-determined does not feel like choice and is not the idea of choice that  people like to have.

My final comment is that since I will experience only one future, and I feel like I am not restrained by a predetermined future, it really makes no difference to me. I will make choices and I will experience the future. There need not be any causal connection between the two : to be more exact I cannot believe in a causal connection between the two because the future cannot affect my choices and I have no way of knowing that the future has changed depending on my choice because I have no way of knowing the future.

But I act believing that I can change the future - once and only once.

Again, sorry for the delayed response. Medical issues again.

The thing to emphasize about hard determinism, which we've been discussing and which forms the background of your questions, is that if it is true, there are only PHYSICAL relations between events, not logical ones. All that is illusion. Which I why I said earlier that if hard determinism is true, there can be no knowledge that it is true, because the reason/conclusion relationship between propositions is caused, not derived.

Any future is simply a physical consequence of the past. one can argue that as we have evolved, physically and culturally, we are arranged to believe that if we have an intention to change the future and find it changed (from what?) when we get there, that our actions caused the change. But, on that theory, there can be no "actions" and no "change." Both are illusions. Everything stems from the characteristics of the particles at the beginning.

The moment we introduce contingency, on which the theory of evolution depends, we are hard-pressed to fit it within a hard determinist theory. Same for quantum uncertainty.

Hope this helps.




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Charles K. MacKay


I can answer a number of questions in philosophy; my academic concentrations (graduate school at Cornell) are ethics, political philosophy, and 19th-century German philosophy (Marx, Hegel, and hangers-on.)



BA, New College, 1971, Philosophy and Religion
Awarded four graduate fellowships upon graduation

MA, Cornell University, 1974
Social and Political Philosophy, Danforth Fellowship

All course work and dissertation drafts completed for Ph.D. Cornell University, 1971-1975, Social and Political Philosophy, Danforth Fellowship

Courses in statistics and microeconomics, George Washington University and The American University, 1976-1978

EXPERIENCE: Health Insurance Specialist 2005 - Present
Centers for Medicare and Medicaid Service
US Department of Health and Human Services

Allentown Business School Instructor (Computer Science) 2003 - 2005

Northampton Community College
Adjunct Professor of Philosophy 2003 -2005

Lehigh County Community College
Adjunct Professor of Philosophy and Computer Science


Medicare Made Easy (with Charles B. Inlander) Addison-Wesley, 1989

Good Operations, Bad Operations (with Charles B. Inlander) Viking Press, 1993

Health Rebooted: Information Changes Everything (in press), 2008

Bachelor of Arts, Philosphy and Religion, New College, 1971 Master of Arts, Social and Political Philosophy, Cornell University, 1975

Awards and Honors
Danforth Fellowship, Woodrow Wilson Fellowship

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