Most scientists and others believe in the so-called laws of physics (as do I). However, important questions about human behavior, psychology, and even free will are tied up in the question of whether those laws are potentially sufficient to explain everything. Are there some human actions, or some aspects of human behavior, that are not fully reducible to the activities of molecules, subatomic particles, and their ilk?

A related question is whether there is any aspect of human thought that cannot be fully, 100% explained in terms of the physical processes inside a brain, such as neuron firings.

The knee-jerk answer from many scientists would be No! Everything in human behavior can and will eventually be explained in terms of molecules. Thought is entirely reducible to brain processes.

I have pondered this question for two decades and seriously tried to accept both positive and negative answers. It is my opinion that if you think in a very rigorous and disciplined manner about these things, you must at least accept the possibility that the answer is yes. Permit me to explain why.

First some basic considerations. The No! answer requires more than just having some physical aspect or process associated with every event. The No answer requires that the causal process be completely and entirely physical. If any part of the causal process involves something that is not physical, then the laws of physics do not furnish a complete explanation. And then we have a Yes answer.

Second, and more important, I have come to suspect that most of my peers in psychology do not properly understand physics. If you had at least two college courses on physics, I ask you to pull out your textbook and spend a few minutes looking at what's inside it. Ask yourself how those laws and processes can explain some social event like the effects of the federal bailout on the national debt, or Sarah Palin's resignation, or the NBA Finals outcome.

Physical laws are based on a tightly limited set of variables. An electron has mass, location, velocity, acceleration, electrical charge. Larger things also have chemical composition and molecular structure. There are a few other variables, but most of them are made out of these few. Force, for example, is mass times acceleration, and momentum is mass times velocity.

I believe that any honest scientist will admit that we cannot yet imagine how social events can be fully explained by physical processes. What I'm asking is only a small additional step: have the courage to entertain the possibility that what you cannot imagine is not there. Social events will not be able to be fully and completely reduced to physical processes. There is something else other than molecules that is needed in order to understand human behavior.

If you are open-minded, I invite you to try this exercise. Don't make a snap judgment on these ideas. Try them out for a couple months. That involves two things: Try seriously and in good faith to see them as correct, and try also seriously and in good faith to find them wrong. Switching back and forth is most effective, I think.

In your college physics textbook you will find many symbols, but symbolism itself is not explained. Symbolism is not a physical relationship. What links the American flag to the American nation, or the dollar bill to a unit of value, or Arnold Schwarzenegger's name to his body, is not contained in the electrons and the physical forces that link things. That connection cannot be expressed in terms of the laws of physics.

Remember, if any part of a causal chain contains things that are not physical, then the laws of physics are not adequate to explain everything. If any physical action is caused partly by something symbolic, then not everything is reducible to physical processes, and we have our Yes answer.

I am going to suggest that the non-physical aspects of reality consist of meaning. Meaning is not, in its essence, a physical reality.

Take the sentence "5x6=22." This is a mathematical expression. It is also a false one. Its falseness is not arbitrary. Every culture that has mastered multiplication knows that that expression is false. But what are the physical properties of its falseness? That falseness does not have mass, or velocity, or acceleration. It does not have chemical composition, molecular structure, or the rest. It is not something "in" your brain, as if destroying your brain or performing psychosurgery on your brain could make it true that 5x6=22.

Chess is a useful example. Molecules do get moved because of chess: pieces get moved around, trophies are manufactured and awarded, cash prizes enable the winner of the game to buy things he or she would not have bought otherwise. But is the game of chess a physical thing? It is not contained in the pieces of a particular chess set, because if you smash those pieces, the game still exists.

It is not equal to all the pieces in all the chess sets in the world. If you smash one set, you have altered the totality of all those pieces, but you have not changed the game. Likewise, manufacturing new sets does not necessarily change the game, even though it changes the totality of chess sets,

The game's existence is not in the neuron firings in the brains of the two players. The game would still exist if one of them had never learned to play, or if one of them dies, thereby ceasing that brain activity. The game exists independently of any particular brain. That makes it impossible to equate the game with brain events.

Money is another good example. You might be misled to think money is physical stuff, because there exist coins and bills, which are physical things made of molecules. But this is wrong, as can easily be shown. First, the equivalence of a dollar bill and ten dimes cannot be explained on the basis of the molecules in them. Second, consider what happened to those Dutch guilders in your pocket when the Netherlands switched to the Euro. The molecular structure of those coins remained the same, but one day you could use them to buy socks, and the next day you couldn't.

Third, economists note that all the dollar bills and coins in the world make up only a third of the total amount of dollars that officially exist. That is, most American money does not have any physical form whatsoever. It exists as only abstract ideas, represented as notional sums recorded in various computers (but hardly being the same as the electrical signals inside those computers; your bank account retains its value even if the bank turns off its computer).

Pi is another excellent example. The value of pi is a mathematical truth, based on abstract ratios of every circle's radius to circumference. If Arkansas had succeeded in passing that law declaring pi to equal 3.0 (in order to make life easier for schoolchildren), things could not have been built properly thereafter. Yet the value of pi is not a physical thing at all. It does not have mass, velocity, molecular structure, or the rest.

Before moving on, let's consider a few other things that are quite important to psychology, insofar as they influence behavior. The English language does not have mass, velocity, acceleration, chemical composition, molecular structure, or other properties of physical reality. The same can be said for democracy, justice, and culture. Laws - here I refer to legal and social entities, not the physical kind - have a huge influence on human behavior, but laws are not physical things, but rather symbolic constraints enacted by elected representatives and applied by police and judges to alter the disposition of individual bodies. The economic crisis and the national debt are having an effect on many of us, but although the national debt can be called "massive," it does not have mass that can be measured (e.g., weighed), the way your body or your desk has measurable mass. It is not a physical thing.

In order to entertain these ideas, people stumble on the alarming thought that I am suggesting that the laws of physics are routinely broken. We have no way to countenance violating the laws of physics.

Relax! The laws are not broken. Nothing that happens has to violate the laws of physics.

All I am suggesting is that physical events are sometimes influenced by non-physical realities. Perhaps another way to put it is that some physical things are capable of allowing themselves to be influenced by non-physical things.

Put more precisely, brains evolved (via purely physical, natural processes) to the point at which they could discover and represent meanings, which are not physical things. The discovery of meaning was a bit like the discovery of oil: A new resource was found that the culture could use for its benefit. The facts of multiplication and so forth were always true, but they had no impact on the physical world until brains evolved to the point of being able to understand and use them. Then they were able to enter into the flow of physical causality and alter the course of events.

Non-physical things such as law, justice, meaning, and the rules of chess can only enter into the causal processes of the physical world insofar as some physical entities (human brains) can represent those non-physical things. Traffic laws cannot move molecules directly. But your brain can understand the traffic laws, by representing them with neuronal and molecular processes, and on the basis of that understanding it can alter your behavior and change the movements of your car. It is not that the ink molecules in the law books in the downtown library somehow exert force across many miles on the molecules that make up your car (or your brain). Rather, your brain uses its physical processes to comprehend those laws, and it directs your hands and feet to do things that it also understands will control your car.

Still, the bottom line is that the physical movements of your car, including all the molecules in it, are caused in part by something (traffic law) that is not itself a physical thing. Your car does not do anything that violates the laws of physics. But the causal chain requires something more than what is explained in your physics textbook.

If the laws exist any "where," they exist in the sharedness of understanding. They are not in any one brain, which would entail that changing or destroying that particular brain would change the law. The brains are merely interchangeable, replaceable units that represent the laws. Sharedness is not a physical place but a social fact. Social reality is not reducible to physical reality.

One of the biggest wrong turns in Western intellectual history goes by the name of Cartesian dualism. DesCartes said there are two kinds of reality, mental and physical. Mind and brain are separate kinds of things. The soul can intervene (somewhere around the pineal gland, supposedly) to guide behavior.

Western thought has struggled for centuries to get rid of that way of thinking. In the process, we throw the baby out with the bathwater. All dualistic thinking has come to be tainted by Cartesian dualism. DesCartes gave dualism a bad name.

In my view, DesCartes was promoting the wrong dualism. Mind is not the second form of reality.

Rather, meaning is the second form of reality. My thought is based on two assumptions. First, meaning is real. Second, meaning is not a physical thing.

The claim that meaning is real seems quite correct to me. After all, people do act on the basis of meanings. Meaning thus does influence the course of physical reality.

The second claim, that meaning is not a physical reality, was the focus of my explanation above. Unless you can specify the mass, velocity, acceleration, molecular structure, and other physical properties of language, justice, democracy, the national debt, and other social realities, then I think you have to allow that meaning is not purely a physical entity.

Again, I invite readers to try out these ideas for a while. Try to see them as correct, and then try to see them as wrong, and then correct again, and so forth.

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A Scientific Breakthrough on Free Will is a Reply by Jeremy E Sherman Ph.D.

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