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Friday, December 26, 2008

do we have free will?

Tom Siegfried says no in this month's Science News. Recent scientific studies have focused on the parts of the brain that are activated during decision making, particulary the habenula, a mass of cells located near the pineal gland. Humans share the habenula with almost all vertibrate animals.

What does the habenula do? For one thing, it appears to reduce the possibility of making bad choices:

When a monkey is faced with a nonrewarding choice, neurons in the lateral part of the habenula fire their signals rapidly, Hikosaka and Masayuki Matsumoto reported in Nature last year. When the habenula neurons fire, dopamine neurons slow down. Apparently the habenula warns against bad choices by suppressing dopamine activity, either directly or perhaps via intermediary neurons.

But that's not all! You also get this at no extra charge:

Habenula activity has been implicated in everything from stress and anxiety to psychiatric disorders and sleep. Besides influencing dopamine cells, for example, signals from the habenula suppress neurons that make serotonin, the brain chemical famous for its effects on mood. Mirrione and her collaborators at Brookhaven have shown a link between elevated habenula activity and symptoms of depression in rats.

If elevated habenula activity is linked to depression, then perhaps medications that reduce habenula activity might relieve depression in people who do not respond to other drugs.

Depressed people typically forgo pleasurable activities that would ordinarily elicit “go” signals from dopamine neurons. An overactive habenula, by damping dopamine, could drive depression by denying the brain the power to choose pleasure. Many popular antidepressants work by elevating the brain’s serotonin levels, perhaps countering the habenula signals that suppress serotonin production. But such antidepressants don’t always work. Direct intervention in the habenula might offer an alternative, Mirrione says.

And speaking of drugs:

Other studies hint that the habenula plays a role in nicotine withdrawal behaviors, with implications for helping people to quit smoking. Behavior underlying other drug addictions might also be disrupted by intercession in the habenula, Israeli scientists reported at the neuroscience meeting. Their study found that deep brain stimulation of the habenula influenced the desire of addicted rats to self-administer cocaine.

So it looks like habenula research has opened a number of paths for further study. If even one of these leads to new treatments that can help people through their struggles, that's good news.

But what does this have to do with free will? Siegfried concludes:

Asking whether humans have free will is like asking which came first, chicken or egg. It’s not a meaningful question. … For free will, the issue is understanding the complex circulation of molecular information that is massaged and manipulated at various stations by neural systems tuned to multiple decision-making considerations. That process is free will, even if it isn’t really free.

Now maybe my habenula is preventing me from understanding, or maybe I'm just dense, but it looks to me like Siegfried is merely introducing "free will" undefined at the end of the article, solely to dismiss it.

Granted, scientists are learning more about how the brain chemicals affect our behavior. In some cases, it appears that these chemicals prevent us from doing things we otherwise might want to do. So does that mean our will can't be free? Honestly, I don't see the connection.

Quite apart from brain chemicals, there are a number of factors that might reduce our ability to make choices: physical ailments, economic hardships, and oppressive governments, to name a few. These things have all been known to exist since before the free will debate began, yet we don't see anyone claiming, "Influenza is free will, even if it is not really free."

Now I'll admit that our own brain processes are much more intimately involved in our day-to-day behavior than is the occasional viral infection. However, when Siegfried makes the leap to, "brain states dictate the behaviors that masquerade as free choices," I'm baffled. Is he saying this is an either/or proposition? The implication seems to be that in a world where we had free will, brain states would not be involved in our behaviors.

I might suggest that a healthy, politically and economically free person might possess a will which is somehow able at a pre-conscious level to adjust brain states to aid in decision making. But in doing so, I'd be leaving the land of science. After all, where would we locate this will? How could we study its effects? What kind of experiment could either confirm or falsify this hypothesis?

So scientists don't bother with questions about free will. That's understandable. What's not understandable — not even tolerable — is the idea that therefore such questions are not meaningful. Each of us has our own way of finding meaning in life; it's even possible that the decision about what is meaningful is an exercise in free will.

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At 12/26/2008 4:25 PM, Blogger Steve Hayes said...

At the philosophical level, the libertarian argument is that while determinism may be true, it is meaningless to assert it, because that is as much determined as anything else.

At 1/04/2009 8:26 PM, Blogger philobyte said...

If we have a wind up toy that walks, does it have Free will? Well it only walks forward. But on an uneven ground, it can "decide" to fall over.

Instead of a wind-up toy, take Honda Asimo, a robot that likely makes millions of decisions per second to walk. As time goes on, perhaps Asimo++ will be applying billions of rules & decisions per second to decide what to do next. The folks who built the robot will not be able to tell you ahead of time what Asimo++ will do (though they will have a pretty good idea.)

Similarly look at Stanley, the robot that won the Darpa Grand Challenge in 2007 (or was it 6?)

I would say that once the outcome is not predictable from the inputs, that entity, for practical purposes, must be treated as though it has free will.

What about Dogs?
Do dogs have free will?

No, only chimps?

Only humans? how do you define free will such that humans have it and the other machines on the planet do not?

At 1/05/2009 12:13 AM, Blogger BruceA said...

Philobyte -

It's not clear to me that we should define free will in such a way as to exclude other animals — or even robots if they are able to make decisions that cannot be predicted even in principle.

I don't think any existing robot, even Stanley, are at that point; to successfully navigate terrain, it must be programmed for recognizing what sort of obstacle it is facing and for handling the obstacle in a way that enables it to meet its goal. For that matter, the goal must also be programmed.

Animals are another story. I'm not convinced either way, but the more evidence I see, the more I would lean toward recognizing that if there is such a thing as free will, at least some animals possess it.


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