Today’s Aquinas: Do Humans and Animals Think in the Same Way?

Today’s Aquinas: Do Humans and Animals Think in the Same Way? April 27, 2015

ThomasAquinas Last week’s discussion of “nobler beings” predictably started a comment thread about the nature of intelligence and the intelligence of animals, with excursions on language and tool use.  Thomas believed (as did Aristotle before him) that human intelligence is qualitatively different than animal intelligence—that human beings are defined as being the kind of animal that reasons.  I might add that reason, to Thomas, encompassed more than logical argumentation.  Human reason encompasses three things, the Three Acts of the Mind.

First, given a sensory impression of a thing, a human being can abstract from it the essence of the thing: can recognize it at as a dog, or a tree, or a triangle, that is, as a member of a class having things in common with other members of that class.  As an example, I might see a triangular “Yield” sign, and recognize it as a triangle with rounded corners, where a triangle is a closed plane figure with three sides and three angles adding to 180 degrees.  I might further recognize it as an isosceles triangle, one with two sides and two angles the same.

The thing to note about this definition is that it applies to all triangles, regardless of the length of the sides or how it is drawn or what the angles are.  You can’t draw a picture of all triangles at once, but you can define them all at once.  Thomas and Aristotle would claim that this is a uniquely human ability.

Second, human beings can consider a proposition and judge it as true or false.

Third, human beings can reason from premises to a conclusion in a logical fashion.

One might jest that they’ve met people who don’t seem able to do these three things, but in fact we all do them constantly.  If you tell me it’s raining, and I’m standing bone dry under a clear blue sky, I’ll surely tell you you’re mistaken, and so would anyone else.  If that last slice of cake is missing, and I didn’t eat it, I know that someone else must have.  This isn’t rocket science; it’s basic human equipment.

Thomas and Aristotle would make a further claim: that human reasoning cannot be explained in purely materialistic terms.  There must be a component to the human being that is immaterial: that exists, and operates, but is not explainable in terms of the body (though it will certainly need to work with the body).  This is how human beings have immortal souls: the material is naturally corruptible, but the immaterial is not.  (I do not intend to try to prove this statement here; the go-to writeup is James Ross’ 1992 paper “Immaterial Aspects of Thought”).

This understanding of human reason is no longer as common as it once was; most people more or less assume that animal intelligence is on a spectrum with snails, say, at one end, and human beings on the other.  Some animals rank highly (dolphins, apes, crows, some parrots) and others do not.  From the scientific point of view (and science has nothing to say to the immateriality of thought, which is not susceptible to experiment), this seems a reasonable assumption, although I believe it to be wrong on philosophical grounds.

Even if you disagree with me, let’s assume for the moment that the above statements are all true: that human reason is as I’ve described, and that human reason has immaterial aspects.

The question, then, is this: are humans in fact alone as “rational animals”?

If there is intelligent life on other planets, life capable of the three acts of the mind, I would infer that they too are “rational animals” with an immortal soul.

But what about the various smarter animals on our planet?  Do chimpanzees reason?  Do dolphins reason?  No one knows for sure.  The experiments with Koko the Gorilla are suggestive but inconclusive.  Is there a form of animal intelligence that is qualitatively or quantitatively less than human but still has immaterial aspects?  I don’t know if that’s even possible.

In any event, for Thomas et al, the mark of intelligence is the three acts of the mind, not simply the ability to use speech or tools.

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photo credit: Public Domain; source Wikimedia Commons


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