Philosopher’s Corner: The Existence of Free Will

James Burkett and Katherine Bryant

Originally published Spring 2012.

Against free will

sulcus128Free will is a messy business. No one could dispute that we go about our daily lives with an ability to make choices. The common idea of free will that most people have is of a “self” within us that chooses freely between our various options, and that our freedom of choice makes us morally responsible for our choices. Yet, this common conception ultimately turns out to be inherently contradictory.

Let’s consider the most common definition of free will: the ability to make choices free of influence or constraint. However, information itself influences us. Any relevant information that is known to us becomes a factor in our decision-making process, as does higher-order information from both rational mechanisms (reason, logic) and irrational mechanisms (emotion, intuition) of thought. The only decision which can be completely free of these psychological influences is one about which we have no information, and which is therefore completely arbitrary. A free will that can only act to make completely arbitrary decisions seems highly impoverished.

What about physical constraints? We cannot choose to fly upward into the air, or to run 30 miles per hour, or to see in the dark; those are not possible modes of operation of our human bodies. Neither can a rock choose to have a conversation. Our choices are both limited by and created by the physical matter that comprises our bodies, how it is assembled, and how those assemblies interact. Inasmuch as our consciousness is based on a physical system, the possible states of that system both limit and create the possible outcomes of rational and irrational thought. Therefore, it would seem that the only degree to which we are capable of decisions free of physical constraints is the degree to which our consciousness is based on non-physical material, such as a spirit or soul. This brings up the centuries-old dualist problem: if there is some other material that comprises our “self,” how does it interact with our physical self? In what way could such a non-material substance affect our physical substance, and if it does so, shouldn’t the effect be physically measurable?  Assuming such a “second substance” does not exist, it follows that all possible states of consciousness must be physically constrained.

Look, Heisenberg was uncertain about a lot of things, okay?
Look, Heisenberg was uncertain about a lot of things, okay?

The notion that we can make choices “free of influence or constraint” has been dealt serious blows. However, there is another definition of free will, alternately known as the principle of alternative possibilities: a choice is free if it could have been otherwise. Some argue that matter itself is inherently probabilistic, and therefore a purely physical system can be uncertain, leaving open multiple possible effects of a single cause. Proponents of this view often point to the Heisenberg Uncertainty Principle, saying that this shows that matter itself is unpredictable. However, according to Heisenberg, this is a measurement problem, not a fundamental property of the universe. Heisenberg’s Uncertainty Principle states only that momentum and position are non-commutative properties, meaning that they cannot be measured simultaneously: the more precisely one is known, the less precisely the other can be known. This is a type of observer effect, such as is seen in many areas of science, and not a source of intrinsic unpredictability for all matter.

However, even if it were the case that matter is inherently unpredictable, this would not make for a particularly desirable free will. If matter were random and probabilistic, this would mean that variation in the operation of matter due to Heisenberg uncertainty would also be random and probabilistic. A system that produces random and probabilistic choices may certainly be unpredictable, but it is not “willed” in any meaningful sense.

The very concept of free will is inherently contradictory. We imagine our will being some inherent property of our “self” that chooses our actions. We think of a choice being free if it is not determined by physical constraints. Yet our “self” is a fundamentally physical system. Thus, the concepts of “free” and “will” are mutually exclusive. You cannot have a physical system that is not bound by physical laws.

So, if we do not have free will, what do we have instead? We have a vastly complex system capable of integrating sensory information with intrinsic goal states in order to select between multiple apparently possible action plans. This system also has a sophisticated feedback capability, which allows it to reflect on past action plans and re-evaluate their effectiveness in achieving intrinsic goal states. We can make choices, transform choices into action, and reflect upon our actions, despite the fact that those choices may actually be the result of predictable physical processes. In short, we have a will that is not free.

In favor of free will

sulcus130Do we have free will?  Do the physical constraints of our existence preclude “choice” in any meaningful sense?  My esteemed colleague has argued that the physicality of our brains and bodies necessarily means that all our decisions and actions are predetermined.  He argues further that choice is only free if other choices could have been made.  In this essay, I will discuss the relationship between materialism, determinism, and reductionism; different interpretations of determinism; and finally, how the relationship between mind and brain is a complex one which, in the context of a material, deterministic universe, ultimately creates what we know as “free will”.

Determinism and free will are closely linked.  Determinists believe that every causal event is predetermined.  Simply put, every event, including every particle’s movement, every planet formed, every life form that has evolved, and every human that has existed and will exist, was all set in motion from the time of the big bang. There is no ambiguity in these events; it is not possible for them to have happened any other way.  The determinist approach to the question of free will is that human decision-making is no different.  Each choice that you or I make was predetermined since the beginning of time.

Arthur Schopenhauer (1788-1860): Although you may disagree with some of his philosophical principles, you cannot argue with his hairstyle.
Arthur Schopenhauer (1788-1860): Although you may disagree with some of his philosophical principles, you cannot argue with his hairstyle.

The 19th century German philosopher Arthur Schopenhauer summarized what is known as incompatibilism, a subset of determinism, when he wrote, “You can do what you will, but in any given moment of your life you can will only one definite thing and absolutely nothing other than that one thing.”  Incompatibilists argue that free will is incompatible with determinism.  Schopenhauer specified that we perceive that we have free will because we approach our experience from an a priori perspective; however, when an individual reflects a posteriori, he or she should realize that free will is an illusion.

Incompatibilism lends itself quite easily to the necessarily materialistic mindset of the scientist. Thus, the inevitability of the motion of particles in the universe applies to our decision-making as well, because if the brain is made of physical material, it should be subject to the same inevitability.  As neuroscientists, we are in the business of describing the mind as the brain, and the brain as a collection of cellular and molecular processes.  If neuroscientists usually study neurons, glia, and the molecules that make up these cells, does it follow that the mind (and the origin of will) is reducible to these discrete parts?

A reductionistic approach may work for other branches of science, such as immunology or physiology, but the brain and the mind are different in important ways. We may describe the circulatory system, the immune system, or the nervous system in multiple levels of description: from molecular, genetic, and cellular levels, to networks and systems, and up to outcomes or behaviors. The important question is which level of description is appropriate for describing the properties of the mind.  Since the job of the brain is to encode information and retrieve it appropriately, and because we know this information is stored in networks, the network level is a useful place to start.

The brain operates by forming complex networks of communication between individual neurons, and the precise firing of these networks in organized patterns allows consciousness to emerge.  In addition, there are hierarchies of information, from bottom-up sensory inputs to higher-level inference and information processing.  This hierarchical information structure creates a system that is more than the sum of its parts.  You may perceive the color green and two edges, but it is your hierarchical inference that allows you to know you are looking at a blade of grass.  So while multiple levels of description are important, we should not confuse a part of the system as the system itself.  The mind is the brain, but it is also an emergent property of the brain.

Given a computer as powerful as the human brain, we might be able to simulate the decisions that a particular brain would make.  An incompatibilist would then argue that there is no free will, because we can predict its decisions: they would be identical to the original brain.  I argue instead that this brain simulation would produce the same outcomes because it is doing the same job that the simulated brain would do. Our brains and minds are part of the process of determinism, and, in fact, make manifest deterministic events.

Determinism and free will are not incompatible. Incompatibilists rely on reductionistic principles to support their position that determinism undermines free will.  However, the mind emerges from the network-level processing which occurs in our brain.  This emergence is precisely what is ignored in reductionism. Compatibilism solves this problem by demonstrating that the mind is what the brain does, and the brain’s job is to make decisions. In contrast to Schopenhauer’s assertion, a posteriori determinism does not equal a priori determinism (“fate”).  Free will is not an illusion.

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