Free will, determinism, and “the nudge”

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Over thousands of years, humans have placed a lot philosophical and theological baggage on the overlapping concepts of free will, choice and volition. We have developed elaborate systems of ethics and religions to articulate “the right” choices to be selected from the array of options open to us daily. Yet there remains a split among neuroscientists as to the nature of this process, especially in humans, down at the brain neuron level. It seems that the deeper you dive into brain chemistry, the harder it is to find that spot where the “cake or fruit” selection actually occurs. [1]

This post is my attempt to articulate my perception of the consensus of views, probably overgeneralizing more than either side of the split would like. Both sides agree, however, that there is likely no single “decision-maker” inside our heads as we often picture being “in charge.” For more on this topic, read my recent post, “Me and my homunculus.”

Sam Harris, a vocal proponent of the Determinist camp, says that free will is an illusion. You exist in a physical world where what happens next is inevitably a function of where you are right now. [2] Daniel Dennett, who is a Compatibilist, asserts instead that free will and determinism can be found to co-exist if we better understand how the brain works. [3]

Both Harris and Dennett are philosopher/neuroscientists, trying to integrate both classical reasoning and science into their positions without bringing in the supernatural, and they are both well worth reading. Both, however, are often seen as threatening to the traditional religious community, which relies heavily on a theological adaptation of agency, the insistence that humans were created as morally responsible agents. The Garden of Eden story is the frequently-cited scriptural basis for this theology. [4]

In the world of Christian theology, this debate has classically been between the proponents of John Calvin’s predestination of the “elect” (God knows everything, including where you will spend your eternal reward) versus those who assert that humans will be saved or damned based on their own human “free will.”

The compatibilist argument

Compatibilists like Daniel Dennett assert that biological “free will” can coexist along with the undeniable subconscious choices, like perhaps choosing between the cake or the fruit, that we make all the time in living our lives. But he would likely say that his perception of free will and yours are probably quite different from each other.

Dennett’s defense of volition comes in the form of his view of the human brain (indeed all animal brains) as an evolved “expectation-generator,” a kind of “probability engine” that has evolved to improve our odds for our own species’ reproduction. [5] Brains, from crude to complex, have been making incrementally-better survival “choices” since the first vertibrate brains appeared billions of years ago. Biologist David Sloan Wilson calls these actions “an elaborate mechanism of environmental assessment” for adaptation. [6]

Think of the billions of neurons making up our brains as individual “probability evaluators” using brain chemicals that work together in a “beehive” of coordinated activity, and these neurons then cause the various parts of our body to react to either fight to defend itself, to flee a threat, to acquire food (“I need cake!”) or to seek out a partner for reproducing. [7] In effect they are “nudging” the living body toward probabilistically-better outcomes, which lead to more accurate memories, which lead to an even more likely survival, and with it, procreation of the species.

That is brain function at its most basic, but we can extend the metaphor upwards to more complex decision-making as well. There is a sense that good choices, even if they are probability-based like choosing fruit versus cake, expand the possibility of more good choices down the road. A good career choice, for example, expands the amount of money available to you. Money is basically “quantified economic choice.” The more you have, the more options life presents to you.

And bad choices limit future choices. Poor diet increases the odds of poor health as you age. Incurring debt on an unwise purchase further limits your financial choices down the road because you first have to pay off the debt from the old purchase before you can address other options for your money.

And somehow in all this, our brains are “watching ourselves” make these evaluations of the “best odds,” and our brains are “nudging” our bodies’ functional parts toward most-likely outcomes. We call that “conversation” that the brain is having with itself “conscious choice.” There may also be a predominance of “unconscious volition” mixed in with the conscious choices, but that line may be irrelevant. If we are programmed to “go with the odds,” and if “success brings more options,” then we are, in effect, “choosing,” whether we are conscious of it or not.

Something, somewhere (or perhaps better said as “everything, everywhere”), is “nudging” us toward actions with better odds for survival. Our senses pick up the changing state of nature around us, and our “probability engine” brain is making evaluations and predictions based on that data and its stored memories.

Our daily survival depends on our brains evaluating the odds successfully more often than not, but even that might not protect us from that runaway bus, or crazy guy with a gun who defies the odds. Most of the time, the odds go our way, but sometimes “bad stuff” happens.

Determinism and Infinitesimals

So what, then, is the argument for determinism? The farther you dig into brain chemistry, the more it appears that any given cell action is a reaction from the “time t-1” state that preceded it. It is very hard to “see” either any choice or probability occurring at this level. If every “time t” state of our bodies has a “time t-1” preceding it, then you can walk that back to “time t-2,” “time t-3,” etc., all the way back to our birth, and even back to the beginning of the universe.

In this view, once “time t=0” happened at the dawn of our universe, then every successive state of matter, right up to what you ate for lunch today, was “bound to happen.”

I admit to preferring Dennett’s probabilistic view of volition over Harris’ version of predestination. I liken the “emptiness of choice” found in zooming all the way down to the cell chemistry level to two related historical ideas. The first comes from the 5th century BCE Greek philosopher Zeno of Elea, he of Zeno’s Paradox fame. Zeno created a famous “thought experiment” about very tiny distances. The second comes from the 17th-century attempts by the Catholic Church to squash an emerging mathematical concept about lines with no width, and points of zero size, called infinitesimals.

Alas, both of these stories will have to wait to be told in an upcoming post.


  1. See my earlier post on why choosing between cake and fruit, if presented to us as options, is not nearly as simple as it appears.
  2. Harris, Sam. Free Will. Free Press, 2012. Print.
  3. See, for instance Dennett, Daniel C. Intuition Pumps and Other Tools for Thinking. W. W. Norton & Co. 2013, p. 273. Print.
  4. Genesis 3 and Genesis 4:1-16.
  5. Dennett, Daniel C. Kinds of Minds: Toward an Understanding of Consciousness. Basic Books, 1996, p. 57. Print.
  6. Wilson, David Sloan. Darwin’s Cathedral: Evolution, Religion, and the Nature of Society. University of Chicago Press, 2010, p.83.
  7. Neuroscientists call these “the four F’s. Neuroscientist humor.

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