Tuesday, November 13, 2012

Zombie Philosophy: Is It Coming For Your Brain?

When I told my friends I was helping to put together a conference on zombie ethics with the Emory Center for Ethics, I invariably received one of two responses:

1) That’s really cool! Where do I sign up?
2) Sorry, what?

If you’re in category (1) and didn’t manage to make it to the conference, read on to find out what happened. If you’re closer to category (2), keep an open mind. There may be more going on with zombies than initially meets the eye.

Anatomy of a Zombie
Dr. Steven Schlozman, an Assistant Professor of Psychiatry at Harvard Medical School, delivered the first talk of the morning via Skype. Dr. Schlozman, a zombie fanatic who grew up reading zombie stories and watching movies like Dawn of the Dead, has speculated extensively on what a zombie brain might look like. First, Dr. Schlozman suggests, zombies likely suffer from an underactive frontal lobe that leads to impaired impulse control. Frontal lobe dysfunction might stem from an overactive amygdala, where high levels of activity have been linked to strong feelings of anger and lust. The anterior cingulate cortex, which mediates the signal between the amygdala and the frontal lobe, could also be impaired in a way that eliminates moral restraint. Together, brain dysfunction in these three critical areas could lead to the insatiable bloodlust that characterizes most classical zombies.

Dr. Schlozman cited several other zombie characteristics that may be explained via brain pathology. Impairment of the ventromedial hypothalamus has been associated with extreme hunger, perhaps explaining zombies’ tireless pursuit of human flesh. Further, the slow, lumbering gait often associated with zombies, (28 Days Later, Resident Evil, and the recent remake of Dawn of the Dead being prominent exceptions to this rule) may be associated with lesions to the basal ganglia and cerebellum, brain areas that control balance and motor activity.

Philosophical Zombies
If Dr. Schlozman is correct, Dawn of the Dead-type zombies could conceivably be produced by an appropriate set of neurological interventions. Yet some philosophers have argued that there may already be zombies amongst us: what have been called, fittingly, “philosophical zombies.” Philosophical zombies are posited as materially identical to normal human beings, yet lacking in consciousness. We tend to believe that our friends, family, and coworkers have the same sort of conscious minds that we do, but how do we really know? Is it possible that a person could have the same brain and body as me, but not the same mind?

One rendering of the philosophical zombie problem.
Dr. Robert McCauley, Director of Emory’s Center for Mind, Brain, and Culture, reviewed some of the major arguments for and against the existence of philosophical zombies. According to McCauley, there are two major strands of thought in modern philosophy: monism and dualism. Monism posits that the universe consists of only a single kind of substance. In physicalism, that substance is material; in idealism, it’s mental or otherwise immaterial. Dualism, on the other hand, posits that both mental and physical substances exist. Exactly what it means for a substance to be “mental” or “physical” may be somewhat unclear, but McCauley points out that despite this ambiguity, we intuitively have a sense of what these ideas mean. Regardless of what the world actually consists of, it certainly “seems” that there are physical things, and it “seems” that there are mental things.

In the past several decades, McCauley argues that a new philosophical notion called psycho-social identity theory (PIT) has risen to prominence. The PIT stipulates that mental causation and physical causation are one and the same. As a result, says McCauley, “we know where and how mental causation occurs” – it occurs in the mind, which is also the brain. PIT has proven to be a useful paradigm for modern-day neuroscientists, who have used the assumption that “the mind is the brain” to derive a vast set of empirical findings on how the brain operates.

According to McCauley, philosophical zombies have been raised as one of the main objections to PIT. Some philosophers, most notably David Chalmers, have argued that the conceivability of philosophical zombies suggests that dualism must be correct. If it’s possible to imagine an individual materially identical to myself but with no conscious mind, the argument goes, there must be a kind of substance that is not material. Other philosophers, including philosopher of mind Daniel Dennett, have argued that arguments premised upon philosophical zombies are best understood as an “intuition pumps”: thought experiments that are “wonderful imagination grabbers,” but that rely largely on intuition and often fall apart when exposed to rational scrutiny. From this perspective, says McCauley, positing a materially-identical but non-conscious human is like arguing that health can be removed without damaging organs or materially altering the body.

Given that PIT’s assumptions are foundational to modern neuroscience, the plausibility of philosophical zombies has significant implications for scientific practice. If it’s possible to have a working brain without a working mind, neuroscience may be missing important data by focusing only on material brain structures.

Zombie Freedom
Following Dr. McCauley’s talk, Georgia State associate professor of philosophy Dr. Eddy Nahmias considered a related issue: do zombies have free will?

Dr. Nahmias began by asking the audience to raise their hands if they believed zombies had free will. Nobody, it seemed, believed that this was the case. Dr. Nahmias then asked if humans possessed free will, and most (though not all) of the audience agreed that we do. Finally, Dr. Nahmias asked: why? What is it that grants humans, but not zombies, free will? Answers to this question varied. Some suggested that human free will exists due to our ability to suppress “animal impulses” and “instincts.” Others argued that “working brains” or “personalities” are features that distinguish humans as unique. Dr. Nahmias, however, suggested that a single principle underlies all of these characteristics: consciousness. For Dr. Nahmias, zombies lack free will simply because they lack consciousness.

This issue is important, Dr. Nahmias argues, in light of controversies that have arisen largely in the last decade regarding the existence of free will in humans. Daniel Wegner, Sam Harris, and Jerry Coyne  have all argued that free will is an illusion. According to Dr. Nahmias, these critiques rely on an implicit model that looks something like this:

My own visual sketch, inspired by a model Dr. Nahmias presented at the conference.

In this model, the brain communicates with an immaterial thing called the “mind” or “soul,” in which free will takes place. When the soul has done its work, it communicates a decision back down to the brain, and the brain causes us to take action. Free will skeptics often argue that science has demonstrated the soul not to exist, and this being the case, free will must not exist either.

Dr. Nahmias, however, argues that free will doesn’t necessarily require any notion of an ethereal soul. Rather, he argues that we should proceed from the following premises: first, that we have conscious experience; second, that consciousness is probably located, more or less, in the cortex; and third, that “it would be shocking” if conscious reasoning had no effect on action. Given these premises, we can imagine a free will based simply on the fact that consciousness exists. In this sense, free will exists, and it influences our behavior insofar as conscious states influence our behavior.

Zombies, says Dr. Nahmias, “are a remarkably effective tool for thinking about free will” because they force us to more fully examine our intuitions about what constitutes a free being. Clarity on those intuitions, in turn, is vital to understanding what we mean when we talk about “free will,” and without that clarity it’s difficult to engage on questions of whether and to what extent free will exists.

The Case for Zombies
There’s at least one other reason why zombies might be an ideal starting point for public philosophical and ethical discussions: everyone knows about them, and almost everyone agrees that they’re at least a little bit cool. Personally, I don’t tend to get all that excited about zombies – the only zombie movie I’ve seen recently is Zombieland, and my feelings were mixed – but I’m still a lot more likely to get involved in a conversation that draws me in with this:

A bloodthirsty zombie.

than, say, this:

Rene Descartes.
It’s probably not a coincidence, then, that Dr. Scholzman lectures at the Harvard Graduate School of Education in addition to his work in psychiatry, or that Dr. Bradley Voytek and Dr. Timothy Verstynen  have converted their extended blogosphere discussion of zombie neuroanatomy into a TedX talk on education. Zombies are the rare commodity that can legitimately compete for the highly sought-after Educational Triple Crown of philosophical, scientific, and pop cultural relevance. For that reason, I wouldn’t be surprised if academic discussion on zombies mirrored the modus operandi of zombies themselves: understated, powerful, and ceaselessly searching for new brains in which to propagate themselves.

Want to cite this post?
Gordon, R. (2012). Zombie Philosophy: Is It Coming For Your Brain? The Neuroethics Blog. Retrieved on , from http://www.theneuroethicsblog.com/2012/11/zombie-philosophy-is-it-coming-for-your.html

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