What is Free Will?

This post continues my discussion of free will and determinism in neuroscience. Due to the relatively brief nature of these posts, this discussion is incomplete. However, I hope it spurs additional discussion. I believe addressing free will and determinism allows us to understand the underlying theories and implications of neuroscience and social science research as well as the practical application of that research.

For this article, the main questions are: “Is behavior biologically determined?” and “Do humans have free will?” I will not address in this post the argument between compatibilism and incompatibilism. In response to comments and questions about my previous post, I thought it necessary to attempt to define free will before I write further posts on this general topic of free will and biological determinism in the neurosciences.

In reading some comments to my post one fairly common definition — at least an operational definition — of free will was randomness. In other words, in a psychology experiment, for example, free will is part of the unexplained variance — the randomness in the data. Equating free will with randomness — overtly or not — is something I have heard and read repeatedly.

However, I do not believe that free will can simply equal randomness. Randomness is chance. It is the flip of a coin or the roll of a die. Randomness is unpredictable. However, let’s go with the assumption that free will equals randomness. One of the simplest forms of randomness is a coin flip. That coin flip might seem random, at least the outcome might seem random, but suppose we understand the composition of the coin. We know it has a particular mass; we know the density of the metal as well as any variations in density throughout the coin. We know its precise coefficient of friction, its air resistance, its rotational velocity, and so forth. We understand everything about the chemistry and physics of the coin’s flip. With this comprehension, we can predict with 100% certainty the outcome of the flip. Based on our knowledge we can predict perfectly the outcome. However, our knowledge or predictions do not cause the outcome.

In other words, even with a perfect prediction of the outcome of the coin flip, that knowledge did not cause the randomness of the result. So, am I arguing that randomness is a good definition of free will? No. If we can understand all the chemistry and physics of the coin and its flight, we can then state that the flip of the coin merely appeared random but was in fact determined by the particular interaction between physics and chemistry. In other words, the outcome of the coin flip was determined by the physical world – by the materials of the coin and the interaction of those materials with our material world – even if our knowledge of the material world did not determine the outcome. Therefore, we can create a deterministic explanation for the seemingly random event.

This demonstrates that what appears random can be explained away as determined. Researchers even have deterministic and indeterministic explanations for quantum theory, which also indicates that defining free will as randomness is not sufficient. Thus, randomness is a poor definition of free will because if free will is nothing more than randomness, once we understand our material world perfectly we will perfectly explain all randomness, all previously unexplained variance. This is what some neuroscientists are trying to do with human behavior, although few are willing to take the hard stance of completely denying free will.

So what is free will? I’ll start with an example. Free will is standing out in the sunlight and denying that the sun is shining. Free will can be defined as choosing one’s actions or course. Free will also is frequently defined as indeterminism. What is interesting is that this definition meaning “not determinism,” relies on determinism to define free will. Why do many use determinism to define free will? Because determinism is easy to define — it is a concrete concept. Additionally, it is one of the major philosophical foundations of modern science, in part because we can easily create operational definitions for determinism.

In the biological sciences and neurosciences, in particular, determinism is inextricably tied to biology and materialism (i.e., biological determinism). Most neuropsychologists seek to explain behavior as determined by the interaction between biology and environment (many may have a soft deterministic view but they still want to know the causes of behavior). In forensic (legal) cases, neuropsychologists often clash with the legal system; psychology assumes biological determinism (i.e., causal determinism) whereas the legal system assumes free will (while it does not necessarily deny some form of determinism, the main emphasis is on free will).

In the end, I did not really define free will other than saying that it is not randomness and it is not determinism. Even defining free will as choosing one’s own course or actions is an incomplete definition because as demonstrated above, it is still possible to explain those choices as determined if we resort to reductionism of behaviors. This leads to one of the major problems with determinism — that it cannot really be falsified by science (after all, science does assume determinism to start) but that is a different discussion altogether. As David Hume once said (I’m paraphrasing), “[The nature of free will is] the most contentious question of metaphysics.”

In my next post I’ll address an alternative set of assumptions (i.e., beliefs or explanations) to determinism, particularly biological determinism as is found in neuroscience.

Jared Tanner, PhD

Jared Tanner has a Ph.D. in clinical psychology with an emphasis in neuropsychology. His interests are mainly neuroimaging and neuroanatomy. He spends his research time looking at the structure of gray and white matter in the brains of people with Alzheimer's disease and Parkinson's disease. With a focus on neuropsychology, he is also interested in how normal and abnormal brain structure relates to cognitive and behavioral functioning.
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