# How would one test the hypothesis of human free will?

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In this context, I define free will to mean that a human's high-level actions (not the quantum states of his particles) are not determined, in the same sense that some quantum effects are not determined.

The simplest (hypothetical) experiment to verify the existence of free will would be to observe the actions of a human for a period of time, then "go back in time" to the beginning of the experiment and observe them again, watching for actions that differ from the first run.

Obviously, we can't do that. Is there any conceivable experimental setup that might bring us closer to confirming that we have free will?

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user limulus
retagged Mar 30, 2014
I would guess that your "in the same sense" is a Pandora's box. Related reading: plato.stanford.edu/entries/freewill, en.wikipedia.org/wiki/Free_will.

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user Glen The Udderboat
Very few physicists are interested in free will/consciousness. A very notable exception, however, is Sir Roger Penrose. You might be interested in his books. See e.g. this section of his wiki: en.wikipedia.org/wiki/Roger_Penrose#Physics_and_consciousness

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user innisfree
Also Marvin Minsky has written a lot on this.

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user Mike Dunlavey
@innisfree I'm not sure that Penrose equates free will and consciousness (you don't say that, I know, but your comment might read as such). It seems to me that ultimately consciousness may well become of interest to physicists (or computer scientists or mathematicians): one could imagine scoping out chunks of what we might think of as "consciousness" into reasonably precise terms that we can grapple with, whereas "free will" might be a bit hard to pin down.

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user WetSavannaAnimal aka Rod Vance
how does a person's high level state/actions differ from [the aggregate of] the quantum states/dynamics of his particles?

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user Dave
@innisfree: Not to mention John Conway. See the free will theorem.

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user Dimensio1n0
This question appears to be off-topic because it is about philosophy.

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user David Z

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Free will and determinism are not incompatible. I can predict that when asked, most children will say  ''yes'' to the question whether they want an ice cream cone when I offer one, although it is done out of their free will.

To turn questions about free will into scientific questions, one must therefore define free will and (in)determinism much more carefully.

In some sense, a subject (aggregate of molecules) has free will if its potential actions cannot be determined by what is observable about it from the outside in a reasonable amount of time. but are more or less determined by knowing its inner control structures.

In this sense, modern computers have free will (as we all know - which means it is an easily observable and hence testable fact). It requires sometimes great skill to force your will upon them, just as with people in real life. In this sense, free will is compatible with the strong artificial intelligence hypothesis discussed in http://en.wikipedia.org/wiki/Strong_AI_hypothesis#Strong_AI .

answered Mar 31, 2014 by (15,747 points)
edited Mar 31, 2014
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I will address the "experiment" part of the question, a real experiment.

How have we determined the quantum mechanical indeterminancy of electrons experimentally? We have certainly in general not taken a single electron and watched it again and again going through the loop. We have set up beams of electrons and studied their interactions with other electrons and other particles statistically, or studied many atoms' behavior under radiation etc.

So one could envisage an experiment to test free will in humans by studying statistically the behavior of humans under controlled circumstances. The difference with electrons is that humans are not interchangable, have individual identity, so the experiment should be designed in a manner that identity affects trivially the experiment.

I expect psychologists must have a number of experiments on this.

One has to define "free" for the experiment.

For example: offer the same cheep  bus tickets from Boston to  New York by two different companies, leaving and ending in the same stations, same conditions. Unrestrained people will choose randomly and on average the two companies will have the same number of passengers. Here randomness would quantify "free will".

Another: Take from the college entrance examinations the top two percent and offer them a scolarship  position either at Harvard or MIT. Free will  would give random results and a gaussian over the years. If one measures non gausian behavior one would say that some of the candidates had constraints on their choice and thus not free will.

answered Apr 13, 2014 by (2,005 points)
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Dogs sniff things and spin in circles before they poop. All dogs do this. It's in their genes. They lick things. They smell food and go after it. It's written in their genetics; it's part of their physical programming.

Humans are the same, although we exhibit more complex behaviors, because our physical brain capacity is greater and we have a rich culture that has evolved over time and is taught to each new person throughout their life. It's like the evolution of genes, except instead of genes being the medium, our living brains and our environment (books, structures, theater, etc.) is the medium.

Free will, in the sense that there's some magical separate "decision entity" is completely bogus. It doesn't exist. There's no need for it. It wouldn't explain anything that isn't already completely explainable and obviously physically based.

As for how our choice of action originates; it's a complex system, but physically based nonetheless.

Depending on where we are at any given second, and given what we learned over our lifetime and what we expect to happen, and how those expectations interact with our immediate and long-term needs, we make choices. I am sitting here typing this, but I'm also thinking about my job and survival, and I have feelings of hunger, and knowledge about my daily routine, etc. I'm constantly making predictions, planning, and feeling things. Thanks to a highly consistent universe, such planning and predictions keep me alive. Partly written into my genes and partly learned from the environment.

There's always something going on in the body and the brain. Always, even while sleeping, as long as you're alive. I'm bombarded by advertisements, other people, sounds in the environment, my dog, airplanes, sunlight, clouds and shadows, the furnace kicking on, etc. Levels of chemicals rise and fall and shift and change according to genetic programs and physics. When I get so tired I can't sit here anymore, I'm compelled to go to sleep or risk going insane. Our environment drives us. Electromagnetic fields interact with our brains, as does everything we ingest, see, hear, and feel. Our choices affect us further in a feedback loop. The kind of free will you're thinking of simply does not exist. It doesn't even make sense to propose it. We are what we are.

That's one of the reasons I say that personal responsibility is a bogus concept, at least in the sense of blaming individuals for their actions, using them as scapegoats, when the true nature of problems are distributed in nature. When we blame individuals for their actions, we erroneously absolve everyone else from playing any part, and that's a mistake. We miss the opportunity to find the real sources of problems, like economic inequality, brain tumors, genetic predispositions, etc. It's just simple-minded to judge people for what they do without looking at the bigger picture.

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user Triynko
answered Nov 1, 2013 by (0 points)
Short answer is.. I don't think it's a scientific hypothesis to begin with. What observations lead you to think that the brain and body alone cannot be responsible for peoples choices and behaviors? As far as random events in brain cells go at low-levels, those are present constantly anyway... small vibrations in the ground, radiation, particles in the air we breath in. There's a lot of randomness anyway; no quantum phenomena required.

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user Triynko
A what, they spin in circles before they poop?

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user Andersi2
"free will...is completely bogus" - is that broadly accepted in contemporary philosophy or neuroscience? Regardless, I think this question and answer ought to be migrated.

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user innisfree
Good answer. Actually there is a short documentary by Stephen Hawking that addresses free will and your answer reminded me of it (can't recall the name, sorry, it was something I saw on a 15 hour plane ride). He didn't quite dismiss it as "bogus" though: although ultimately illusory, an approximation that we'd normally call free will drops out as an emergent phenomenon that seems very real and, as you touch on with "predictions [that] ... keep me alive", it's often important to treat it as though "real". Anyhow, the doco was a neat mix of science and philosophy.

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user WetSavannaAnimal aka Rod Vance
Yes, dogs spin before they poop, lol, the same way they spin in circles before they lay down. See answer 4 here: scienceline.ucsb.edu/getkey.php?key=1314 They are basically making sure the area is safe and there aren't any snakes or anything that will jump up and bite them when they are vulnerable. May also have to do with just making their mark more obvious. As far as free will being bogus, I was talking about the idea that there's some independent force external to the body making decisions for us. That's bogus. But the feeling of free will is real, because we are conscious.

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user Triynko
Attention schema is an interesting explanation of consciousness. " Even insects and crustaceans have a basic version of this ability to focus on certain signals. Over time, though, it came under a more sophisticated kind of control — what is now called attention. Attention is a data-handling method, the brain’s way of rationing its processing resources. It has been found and studied in a lot of different animals." aeonmagazine.com/being-human/how-consciousness-works

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user Triynko
To test the hypothesis though, you need to have an actual hypothesis, and I don't think "free will" is a hypothesis, it's just a cloudy idea.

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user Triynko
A better question would be something like whether a stray gamma ray would alter a person's decisions, if you went back in time and repeated the actions. Then you could at least implicate chaos in some way, or even tie it into phase transitions such as this new model: m.phys.org/news/…

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user Triynko
"The key insight in the paper is that the dynamics of complex systems – like the brain and the economy – depend on how their elements causally influence each other; in other words, how information flows between them. And that this information flow needs to be measured for the system as a whole, and not just locally between its various parts."

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user Triynko
This answer is based on giant leaps of faith. It might seem to follow from accepted paradigms that life forms are nothing more than complex computers built up from entangled particles. But there is simply no experimental evidence in favor of this. There are more profound philosophical arguments I could raise, but they are not appropriate here.

This post imported from StackExchange Physics at 2014-03-30 15:47 (UCT), posted by SE-user dj_mummy

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