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Is there such a thing as free will? Perhaps the philosopher who has gotten closest to a sensible understanding of free will is Daniel C. Dennett, who thinks of the phenomenon as “the power to veto our urges and then to veto our vetoes . . . the power of imagination, to see and imagine futures.”

Over the last few decades, science has made small but significant advances in understanding the relationship between conscious and unconscious thought, and the data are beginning to paint a picture that seems to validate Dennett’s views. In the 1970s, Benjamin Libet wired people to an electroencephalogram and measured when they reported having a particular conscious thought about an action and when the nerve impulses corresponding to the initiation of the actual action started. Astoundingly, the subjects had actually made (unconsciously) the decision to act measurably earlier than when they became aware of it consciously. The conscious awareness, in a sense, was a “story” that the higher cognitive parts of the brain told to account for the action.

So science may be showing us that free will is more a feeling than a real manifestation of independent will. As psychologist Dan Wegner put it, “We see two tips of the iceberg, the thought and the action, and we draw a connection.” Libet’s position is a bit more moderate and is akin to Dennett’s. Libet says that free will is a form of veto power, filtering and sometimes blocking decisions provisionally made at the unconscious level.

Quantum mechanics is sometimes brought into discussions of free will by supporters of pseudoscience because it is very technical and, more important, incomprehensible enough to lend that aura of scientific credibility without committing one to specific details. Some philosophers and scientists suggest that perhaps free will can be explained by occasional quantum fluctuations that, by interfering with subcellular phenomena in the brain, create a partial decoupling of our decision-making processes from the standard macroscopic laws of causality. This is nonsense, not only because we have absolutely no evidence of “quantum fluctuations” (whatever they are) at the brain level, but because, even if they did happen, they would—at most—generate random, not free, will. And random will is not one of those varieties of free will that is, in Dennett’s words, “worth having.”

Another source of confusion between science and philosophy when it comes to free will is to be found in the rather vague concept of “emergent properties,” for example, the notion of free will being an emergent property of the higher brain’s functions. Even though some scientists are predisposed to reject emergent properties, “emergence” can actually be studied scientifically and is a rather common phenomenon. For example, when hydrogen and oxygen combine to form water, the resulting molecule has emergent physical–chemical properties, in the sense that the temperatures marking transition states are not simple functions of the properties of the individual atoms.

Some philosophers have argued that emergence restricts the limits of reductionism, not because it isn’t “physics all the way down,” but because, frankly, a quantum mechanical description of, say, the Brooklyn Bridge isn’t going to be very helpful. Emergence entails that certain phenomena are best studied, and understood, at some levels of analysis rather than others, and free will may well fall into this category. To say that it is an emergent property of the brain is not a call for magic or pseudoscience, just the realization that neurobiology and psychology are better positioned than quantum mechanics to understand it.

Adapted from M. Pigliucci, Can there be a science of free will? ©2007 the Committee for Skeptical Inquiry.