Turns out that Galileo was right and Aristotle was wrong: in a vacuum, a feather and a bowling ball will fall from a tall building at exactly the same speed.
Before we can answer the question, “Is intuition a guide to truth?” we’ve got to get clear on what exactly we mean by “intuition,” and particularly by the philosopher’s use of this term.
The colloquial sense of intuition is something like an instinct or premonition, a type of perception or feeling that does not depend on—and can often conflict with—conscious reasoning. Our 2012 show “Gut Feelings” with psychologist Gerd Gigerenzer deals with these kind of intuitions, and the role they ought to play in important decision-making.
But there’s another, perhaps less-familiar, sense of “intuition,” which is the kind that philosophers often rely upon, and these are more caught up with conscious reasoning than intuitions of the "gut feeling" variety are. Let’s call this second kind, “intellectual intuitions.” Philosophers often try to use "intuition pumps” (to borrow Daniel Dennett’s term) as a way of defending a particular philosophical analysis of a thought experiment. Let me give an example.
Probably one of the most famous thought experiments in philosophy, inspired by Descartes’ evil demon, is Hilary Putnam’s “Brain in a Vat.” In it, a living brain is removed from its body, put in a vat of nutrients, and hooked up to a super computer so that it is stimulated in exactly the same ways that normal, embodied brains are. The question is then asked: how would you know, based only on your experience, whether or not you are such a disembodied brain in a vat? Given that we’re hardly going to remove someone’s brain and put it in a vat to find out if there’s an obvious difference in experience, all we can do is think about the case and form an intuition.
As a philosopher, Putnam is rather fond of using these kinds of thought experiments to elicit certain intuitions, though, I have to admit, he usually elicits the "wrong" intuitions in me. In the case of the brain-in-a-vat, the intuition we are supposed to have is that there would be no detectable difference between the experiences of the brain, suitably hooked up and stimulated, and the experiences of a fully embodied person moving about in the world; hence, we cannot escape the radically skeptical conclusion that, for all we know, our perceptions of the world could be completely illusory. (Putnam actually comes to an even more radical conclusion, namely that brains-in-vats couldn't even entertain the thought that they might possibly be brains-in-vats, but we'll leave this aside for now.)
Why suppose intuitions like this are reliable? And what if you don’t share the “correct” intuition? In the brain-in-a-vat thought experiment, you might share Putnam’s intuition if you already endorse a theory that reduces perceptual experience to neuronal processes. But what’s the evidence for that view? Various theories of embodied cognition refute this kind of reductive approach to perception (and its corresponding interpretation of the brain-in-a-vat thought experiment). So, if some version of embodied cognition is correct, then Putnam’s intuition that we wouldn’t be able to tell the difference between normal embodied experience and envatted brain experience would just be plain wrong.
Regardless of what you think about this particular thought experiment, the bigger point is that appealing to intuitions seems like a bad way to do philosophy. First, our intuitions often conflict, in which case, how do we decide whose are correct? Moreover, when our intuitions disagree, it's often because we have different theoretical commitments, and these prior commitments inform what we tend to find philosophically “intuitive.”
But even if we always agreed on our intuitions, why suppose they are genuinely informative about the world? Surely, there are many truths about the world that are just counter-intuitive. Take a very simple case: If you were to drop a feather and a bowling ball from a tall building, which do you think will hit the ground first? The “intuitive” answer, which was Aristotle’s and many other’s, is that the heavier object is going to fall faster than the lighter object. But, as Galileo later proved, it turns out Aristotle and company were wrong.
This case highlights a big difference between science and philosophy: scientists, like Galileo, may start off with an intuition, but they never treat their intuitions as evidence for anything. Instead, they go out and test them, and it’s the data gathered in their experiments that counts as evidence, not the intuition that prompts the experiment. Philosophers, on the other hand, like to sit in their armchairs and come to all sorts of conclusions based on intuition. But why should anybody treat their intuitions as evidence of anything, other than what they themselves think?
One problem with simply dismissing intuitions in philosophy is that, for some areas of philosophy, intuition seems like an indispensable tool. Take moral theory, for example. How do we develop a good moral theory if we don’t start off with at least some intuitions about what is right and wrong and go from there? For example, we're often told as children that we should never tell a lie, but intuition might sometimes conflict with this moral prescription. Imagine you’re in Nazi Germany and you’ve hidden your Jewish neighbors in the attic. The Nazis come, demanding to know if there are any Jews in the house. What does your intuition tell you would be the moral thing to do? Lie to the Nazis, or tell the truth?
My initial response to this kind of thought experiment is this: if your intuition says to tell the truth, all that proves is that you’re an idiot. I mean, why go to all the trouble of hiding your neighbors in the first place if you’re only going to give them up as soon as the Nazis come knocking? Of course you should lie!
Granted, this snarky response slightly misses the point, which is that we have to use intuition to figure out the right way to act, and from there we can start to build a moral theory. Apart from the fact that your behavior would seem illogical were you to just give up your neighbors after hiding them, my guess is that most of us would agree—intuitively—that lying to the Nazi’s to protect your Jewish neighbors is also the moral thing to do.
Ultimately, though, this is not much of a defense of the philosophical use of intuition. I could come up with a bunch of other thought experiments where our moral intuitions don’t offer clear and easily agreed upon answers as to what the right thing to do is. And, like the brain-in-a-vat case, disagreement in moral intuition will often stem from disagreement in prior theoretical commitments. So, intuition can’t support those theoretical commitments—it can only bring them to the surface.
If that’s the case, what does that say about the entire enterprise of moral philosophy? Is there a way to develop moral theories that does not depend on intuition? Or is there a way to rescue the use of intuition in philosophy from the problems I’ve raised here?
Tune in to this week’s show, “Is Intuition a Guide to Truth?” with guest Alvin Goldman, and let us know your thoughts below!