Rationally Speaking

A monthly e-column by Massimo Pigliucci
Department of Botany, University of Tennessee

N. 19, December 2001: "The great unicorn debate"

“I will give you one hundred dollars if you can demonstrate that there is no such thing as an immaterial unicorn in this room.” When I said that to my class of Honors students engaged in a course on science and pseudoscience, they looked at me in disbelief. I suspect that the incredulity wasn’t generated by the obvious impossibility of the task at hand, but by the idea that their professor would put a hundred bucks of his own money on the table to prove a point. So started the great unicorn debate which lasted for several weeks, until the intellectual energy of the participants was exhausted.

The first attempts at solving the problem were generated simply by a misunderstanding of the question: one of the students claimed it was really a straightforward matter; just flood the room and the body of the unicorn would displace a certain volume of water, which would reveal the presence or demonstrate the absence of the beast (apparently, ethical concerns about the possibility of drowning the unicorn did not enter in the proposal). “I said ‘immaterial’, not ‘invisible,’” I remarked. Water, as everyone knows, just goes through an immaterial body without being displaced. “Oh!” Successive attempts were crafted more carefully.

A particularly clever effort—which clearly got the point of the exercise—was: “There are no immaterial unicorns in our classroom, because in our classroom exists an atmospheric condition, undetectable by any tools we might have today, that causes immaterial unicorns to materialize, thereby making them visible to the naked eye.” Talk about beating you at your own game. But I wasn’t about to let my hundred bucks go that easily. I replied that the person in question obviously did not understand the mysteries of unicornism, or she would realize the foolishness of such an attempt.

Another student came up with a more challenging philosophical solution to the problem. It went like this:

Fact one: Immaterial is defined as the absence of matter.

Fact two: Matter cannot be created or destroyed.

Conclusion One: Something that is immaterial cannot be created or destroyed.

Fact three: Thought exists only as something immaterial.

Fact four: Thought exists only in one's own mind.

Conclusion Two: Something immaterial exists only in one's own mind.

Conclusion Three: The presence of something immaterial can be created or destroyed only in one's mind.

Conclusion Four: The creation or destruction of something immaterial in one's own mind is determined by belief.

Final Conclusion: There is not an invisible, immaterial unicorn if one does not believe it in her own mind.

Damn! I wish more theologians displayed such a keen sense of reasoning.

Yet, this still wasn’t good enough, and I asked the whole class to go through the proposed proof, pick it apart, and see where the flaws were. Sure enough, half an hour of discussion revealed several problems.

First, modern physics no longer maintains that matter cannot be created or destroyed. In fact, according to quantum mechanics, such processes go on all the time. The only reason we normally don’t detect them is because they are very fast and balance each other perfectly, so we don’t expect a chair to suddenly appear from or disappear into nothingness. (Although, according to superstring theory, this sort of quantum fluctuation may have been responsible for the origin of the universe, which would have literally popped into existence from nowhere. Spooky.)

Second, who said that thought is immaterial? Some leftover Cartesian dualists might still think that, but in the 21st century it is becoming more acceptable to consider thought an aspect of very physical activities going on inside one’s brain. Indeed, we can now measure which parts of the brain are involved in which sort of thinking and even feelings. This doesn’t mean that we have a full understanding of what thought is. Far from it. But the chances that it will turn out to be immaterial (in the sense of not depending on matter) are pretty slim.

Mind you, I completely agree with the final conclusion: there is no immaterial unicorn unless one believes in it in his own mind. But the only justification I (or anybody else, as far as I know) can give for such conclusion is my own intuition.

The same student also presented another clever argument, this one based on the laws of physics. She correctly maintained that an immaterial unicorn could not be affected by or take advantage of the laws of physics, by the definition of being immaterial. Therefore, we should think of the unicorn rather as an immaterial point with no extension (pace Euclid). Such an immaterial point could not stay in the room because the room itself—along with the earth and the whole solar system—is moving fast through space. The core of this demonstration depends on Descartes’ own intuition of the trouble he got himself into by proposing a dualistic conception of the human body: if the mind is not corporeal, how does it affect the body? Descartes “solved” the problem by positing that the pineal gland was the seat of the soul. But, as every philosopher since him has immediately realized, just because you make the point of contact between material and immaterial as small as possible (the pineal gland is the smallest gland in the endocrine system), the paradox of an immaterial entity acting on matter (or vice versa) doesn’t go away. Indeed, that is what’s so unbelievable about ghosts, ectoplasms and out of body experiences: if you are out of your body, how do you manage to see yourself lying in bed? With whose eyes? What brain is there to process the visual signal? And, given that your sense of self depends on having a properly functioning brain, who is you, when you are out of the body?

But of course, in order to save my money, all I had to reply was that—once again—the mysteries of unicornism tells me that not only the immaterial unicorn is not a point; it also stays in the room with no trouble, it’s a male, five feet tall and of white color (how do I know that it is white if it is immaterial and invisible? Well, you should know by now: it’s a mystery…).

By the end of the day, my students agreed that there was no way to demonstrate the inexistence of the phantom-like unicorn. After having secured my hundred bucks, I then asked if they believed in the existence of the unicorn, nonetheless. There was a unanimous negative response. “Why?” I asked affecting surprise. “Because it’s silly to believe in something for which there is no evidence,” was the equally bewildered response. After a few seconds, somebody asked: “Then what’s the difference with belief in god?” But class time was over, and I left them to discuss theology with the satisfaction of a job well done.

Next Month: "Mr. Bayes and the true nature of scientific hypotheses"

© by Massimo Pigliucci, 2001