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Mental Parasites

by Bill Meacham on September 24th, 2014

What if your brain were taken over by a parasite and made you want something you would not ordinarily want? What if it took over your second-order thinking and made you want to want that thing? Would your will then be free?

This is not so far-fetched a scenario as it might seem. There are numerous examples of parasites infecting the brains of animals to make those animals act contrary to their own well-being. Here is one:

The Lancet liver fluke Dicrocoelium dendriticum has a very busy life. As an adult it spends its time in the liver of a cow or another grazing mammal. Here it mates and lays eggs, which are excreted in the host’s feces.

A snail eats the poo, taking in the eggs at the same time. The eggs hatch in the snail and make their way into its digestive gland, where they asexually reproduce. They then travel to the surface of the snail’s body. As a defensive maneuver, the snail walls the parasites up in cysts and coughs up the balls of slime…doing exactly what the parasites wanted it to do.

An ant comes along and gobbles up the fluke-laded slime balls. The flukes then spread out inside of the ant, with a couple of them setting up shop in the insect’s head. When night approaches, the flukes take control. They make the ant climb up a blade of grass and hold tight, waiting to be eaten by a grazing animal. If the ant is still alive at dawn, the flukes release their control and the ant goes about its day like normal (if the ant baked in the sun, the parasite would die, too). At night the flukes take over again and the cycle repeats until the ant becomes cattle food.(1)

It’s doubtful, of course, that the lancet fluke actually wants its host to do anything. That is just a figure of speech. But what is clear is that the ant’s climbing up the blade of grass has nothing to do with its own survival and well-being. Its mind, tiny as it is, has been hijacked by the parasite. If it had enough mentality to reflect on what it is doing, the ant could probably find plausible and compelling reasons for its actions. Perhaps it feels good to climb. Perhaps hanging out at the top of the blade of grass feels tranquil and comfortable. Or exhilarating. We’ll never know. But we can find out find how it feels in our own case, because we too are subject to parasitic hijacking.

Daniel Dennett makes the point that certain memes have the same effect on humans that the lancet fluke has on ants. A meme is a unit of cultural transmission, similar to the gene, which is a unit of biological evolution. Like a gene, a meme is a replicator, except memes replicate contemporaneously between minds rather than historically between bodies.(2) A meme is an idea or information packet that replicates itself by passing from mind to mind. Says Dennett,

It’s ideas – not worms – that hijack our brains. … There are a lot of ideas to die for. Freedom. … Justice. Truth. Communism. Many people have laid down their lives for communism, and many have laid down their lives for capitalism. And many for Catholicism. And many for Islam. These are just a few of the ideas that are to die for. They’re infectious.(3)

Such hijacking might be innocuous and unintended, the product of cultural memetic replication like a catchy tune, or it might be quite deliberate, as in brainwashing or propaganda. For example, here are a few memes that may have been installed in you or someone you know.

  • Those of other religions than yours are heathens and infidels and must be stopped at any cost.
  • Your form of government is the best one and works for your benefit.
  • People of your race (or gender or nationality, etc.) are better than those of other races (or genders or nationalities) and deserve better treatment.

And so on. You can probably think of more. In all these cases, our beliefs can induce us to act contrary to our own well-being (and to our genetic fitness as well, but that is not usually our concern).

But regardless of the effect on our own well-being, when we are so induced we seem to act as we do voluntarily, of our own free will. And yet, something else – our parents, our community, our culture, the information media we are exposed to, the government, the dominant economic class, etc. – determines our will, i.e. what we want, choose and strive for. And furthermore, that something determines our second-order will as well, what we want to want.

I have noted with approval philosopher Harry Frankfurt’s notion that freedom of the will consists in being able to make second-order volitions effective. It is second-order volition – our ability to control what we want based on our capacity for reflective self-evaluation – that distinguishes us humans from other animals. Our will is free, he says, when we succeed in making our second-order volition effective; that is, when the second-order volition actually governs the first order such that the preferred first-order desire is what results in action. When that happens, we judge that our will is free.

But what if somebody else controls our second-order will? Such a thing is quite possible through brainwashing, application of propaganda, and also operant conditioning and behavioral engineering as depicted in the novel Walden Two.

Robert Kane calls such control Covert Nonconstraining Control, or CNC. In cases of constraining control, a person is forced by physical causes to act against his will, for example by being physically threatened or locked up. In cases of nonconstraining control, a person’s will is manipulated so that the person willingly does what the controller wants done. The person is not obviously constrained, but is controlled nonetheless. Examples include operant conditioning, behavioral engineering and other forms of manipulation. CNC, covert nonconstraining control, occurs when the manipulation is hidden from the person being manipulated; that person does not know he or she is being manipulated and perhaps does not even know that the manipulators exist.(4)

When we find out that we have been manipulated we typically feel outraged. Take the fictional account of the fantasy world of Harry Potter. In that world one of the unforgiveable curses is Imperius, by which the witch or wizard controls the victim’s will. It is unforgiveable because it violates one of the most central aspects of our identity, the sense that we are in charge of our choices, and that our choices define (or reveal) who we are. Nobody wants to be a puppet. (The other thing that is central to our identity is how we perceive reality, our own unique point of view. But our perception, seemingly more passive, is not quite so central. Were we to find out that someone had distorted our perceptions, we would feel anger at being lied to, but not, I suspect, outrage at being controlled.)

So is our will free when we are covertly constrained? No, obviously not. Our choices and resulting actions are not ours, but our controller’s. But do we still have free will? In the sense of having the capacity for it, yes.

That capacity – whether or not it is actually exercised at any given time – is rooted in our capacity for reflective self-awareness, or second-order thinking. If your second-order will is determined by someone else, as soon as you know it you can take steps against it. Or for it, if you decide you like it that way. The point is, once you know someone is trying to control you, you have a choice about it. Second-order thinking is, potentially, self-correcting.

Now clearly it might not be so easy to find out. If your manipulator is sufficiently skilled, it might be very, very difficult indeed. You would feel no impulse to find out if you did not even suspect that you might be subject to manipulation.

That’s why philosophy is, in some ways, a subversive concern. Socrates famously asserted that the unexamined life is not worth living.(5) If we desire wisdom we are advised to examine our lives even if there appears to be nothing to be concerned about. A manipulator would not want you to do that, because you might discover the manipulation. Having discovered it, however, you would be better off, as you could then take steps to take back your will.

Eternal vigilance, it seems, is the price not only of political liberty(6) but of freedom of the will as well.


(1) Bennington-Castro, “12 Real Parasites That Control the Lives of Their Hosts.”

(2) Dawkins, The Selfish Gene, chapter 11, pp. 189–201.

(3) Dennett, Daniel C. “Dangerous Memes.”

(4) Kane, The Significance of Free Will, pp. 61-67.

(5) Plato, Apology, 38a.

(6) Berkes, “Eternal vigilance is the price of liberty (Quotation).”


Bennington-Castro, Joseph. “12 Real Parasites That Control the Lives of Their Hosts.” Online publication as of 19 September 2014.

Berkes, Anna. “Eternal vigilance is the price of liberty (Quotation).” Online publication as of 24 September 2014.

Dawkins, Richard. The Selfish Gene, New Edition. Oxford and New York: Oxford University Press, 1989.

Dennett, Daniel C. “Dangerous Memes.” Online publication as of 19 Sept. 2014.

Kane, Robert. The Significance of Free Will. Oxford: Oxford University Press, 1998.

Plato. Apology. Tr. Hugh Tredennick. The Collected Dialogues of Plato. Ed. Edith Hamilton and Huntington Cairns. New York: Pantheon Books, 1963.

From → Philosophy

  1. Terry Cowan permalink

    Really nice work and very relevant to the lack of/slow pace of transformation humanity is experiencing universally and individually to a regrettable degree (including me). Being a conscious being requires knowledge AND focus. Love your use of science as examples, science being the religion of rational thinking (for the most part).

  2. Interesting Bill. Perhaps we should view the whole marketing industry as a mental parasite. It is certainly infectious, ubiquitous and invasive and seems to get people to go to malls, park a long way away in terrific heat, buy useless garbage, and go into debt doing it.

  3. Very even handed and understandable. Clear. I think I’ll forward it to my son. Thank you for writing and sharing this.

  4. Bill, how if at all does your argument withstand attacks of the form made by Plantinga and others, e.g. on the irreconcilability of naturalism with evolution?

    First, would you agree that to apply your argument to humans, we need to take some kind of materialist position: i.e. one that holds that consciousness, (and so, I assume, second-order volition), is “nothing but” a property emergent from, or supervenient on (etc) the physical brain? In which case, Lancet flukes in ants, and memes in humans, along with the free-will-stealing processes are *physical* things. Yes?

    And we know that such physical processes in living organisms are governed by evolution.

    However, we also know that evolution adapts creatures towards survivability, and not, per se, towards truth preservation. In fact it’s clear that truth can go shoot itself in the head in a lot of survivability cases. Truth-preservation, then, is unlikely to be selected for in and of itself if at all.

    But in that case, we take a serious hit in our confidence in the validity of Dennett’s position, but also on the very argument *you* just made. You and Dennett are not evolved to produce valid, truth-preserving arguments. You are evolved, rather, merely to survive long enough to reproduce.

    Now this problem exists only *if* naturalism is asserted. However, to the non-naturalist, there is no problem. In that case, while cognitive interference may still occur, it is occurring in the *brain*, not in the *mind*, and we can propose the latter as being the truth-preserving entity.

    (Of course that opens a whole can of worms about the interaction between brain and mind, although in truth that can has been open and wriggling for years now.)

    • Bill Meacham permalink

      Thanks for your comment, Tommy. I do not agree that to apply my argument to humans we need to take a reductive materialist position about consciousness. Or, as I prefer to say, about mentality or subjectivity, as “consciousness” is quite a slippery term. I merely assert, along with Dennett, that ideas can hijack our minds, in the sense that they can get installed and become operative without our witting consent. That’s true regardless of the ontological nature of mentality; i.e. regardless of whether we take mentality to be nothing but an arrangement of physical stuff, or a phenomenon that emerges when the arrangement of physical stuff gets sufficiently complex, or one of the dual aspects of stuff (the other being physicality), or an entirely separate kind of stuff from the physical, or any other such theory. Whatever mentality turns out to be, memes (ideas, attitudes, beliefs, etc.) can and do become operative such that they influence our behavior without our noticing it. (Not all of them, of course, are so covert. We can take a hand in deciding what memes to entertain and permit to have an effect on us, but that is another story.)

      I’m not sure how to respond to the rest of your comments now that I have rejected your premise.

  5. Bill. I find your reviews insightful especially the recent philo now on ethics. In this case however, missed the connection between parasitic biological determinism in animals and denial of free will in humans. Can you elaborate on how the former leads you to the latter?

    • Bill Meacham permalink

      The former does not lead to the latter. The connection between biological parasites and memetic parasites is by analogy. The point of the essay is that memes can seem to take over our minds, and when they do it is as if we have lost our free will. But we always retain the possibility of reclaiming it, so I don’t deny free will in humans as a capacity. I only note that in some cases we fail to exercise it.

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