What is the single greatest mistake that influential thinkers make, but Aristotle and Aquinas avoid?
The secret to making better arguments and not being deceived
When teaching at St. Mary's College in California, a certain philosophy professor, of happy memory—a wonderful teacher and disciple of St. Thomas—would need to get permission from the Bishop’s office to use certain books because, at the time, he was teaching a course in Marxism. He needed to use The Essence of Christianity by Ludwig Feuerbach, first published in 1841. The bishop called him in and said to the effect, I’m giving you permission to use the book, but you are responsible if anyone loses their faith. The professor agreed that such a warning should be said and that if you had to read all of Feuerbach’s book, that would be a dangerous thing. He was using the book only for a single argument, a very dangerous argument, an argument that greatly deceived Marx and Engels. The professor was using Feuerbach to show the dangers of making a certain mistake in thinking. What was Feuerbach’s mistake?
Before going into Fuererbach’s particular mistake, we need to give context about the most common kind of mistake made, even by the greatest thinkers, authors, and leaders. It is the first kind of mistake that Aristotle points out in his Sophistical Refutations and it is also the first lesson he gives in his Categories. It is an error in our use of language—what is called the fallacy of equivocation.
What is the fallacy of equivocation?
The fallacy of equivocation is the mistake of mixing up the senses of a word.
Or one could say this:
The fallacy of equivocation is the mistake that results from not seeing the distinct senses of a word.
Sometimes we play upon the different senses of a word, and people immediately know. Here is a very easy, classic example:
Roger Merris hit 61 home runs with a bat.
A bat is a flying rodent.
Therefore, Roger Merris hit 61 home runs with a flying rodent.
It's not an argument that we can trust at all. It is an argument that is simply bad. No one is going to be deceived by that argument because anyone can see the two meanings of the word “bat”.
Here is another example, perhaps slightly less obvious:
Chianti is a dry wine.
What is dry is not wet.
Therefore, Chianti is not wet.
Nobody is deceived by that argument either. Wine must be wet. There is, then, a mixing up of the senses of “dry”. What are the senses of “dry”? To distinguish the senses of a word, look at their opposites. Dry is opposed to wet, and dry is opposed to sweet, right? So when you say Chianti is dry, it's dry in the sense of being opposed to sweet. When you say, "dry is not wet," it is dry as opposed to wet.
Let’s now return to Fuerbach and his mistake of equivocation. In his work, he quotes theologians who say that the unlimited or the infinite is God. That seems like a reasonable statement, right? What is infinite is divine, powerful, and so on.
And then he points out that man's mind is unlimited. This also seems reasonable. We can always learn more, right? We're always inventing something new. There's no limit to it. Do you ever reach the point where you can't learn anything more? No, because you can always learn more, nor do we ever get to the point where we can never invent anything more. You can always learn something more.
In fact, we know the universal, for example, odd number. When I know what odd numbers are, I know an infinity of things, right? When I know something about “even numbers”, I know something about an infinity of things. When I know that no odd number is even, I am making a statement that I know something about an infinity of things. So, in some sense, my mind's unlimited, right? So here is Feurerbach’s argument:
The unlimited is God.
Man’s mind is unlimited
Therefore, man’s mind is God.
That seems like a pretty good argument, right?
“Unlimited” is not like the word “bat” or “dry”. “Bat” has two senses, both of which are sensible and concrete—a piece of wood and a rodent—and everybody probably knows them. The same is true for “dry”. What is wet and what is sweet are sensible qualities and everybody probably knows them.
Many people, however, probably couldn’t say that there are two meanings of the word “unlimited” nor distinctly say what they are.
And if you can't see any distinction between unlimited in this sense here and unlimited there, then you can be deceived by Feurerbach.
Marx and Engels could not distinguish the senses of unlimited and so were deceived by Feurerbach.
What is the difference in meaning, then, between “unlimited” when we say God is unlimited and man's mind is unlimited?
When we say that man's mind is unlimited, we mean “unlimited” in the sense of imperfection. You can always learn something more because the mind can always be improved; it is always in potency to some additional truth. When you say God is “unlimited”, we do not mean that God can always acquire something more. God is an actual infinity, unbounded and already perfect. So right away, there is a difference in meaning.
Someone can have a hard time expressing that difference, so many end up making a mistake, even great minds. So you begin to notice that there are multiple senses for many words, especially important words we use all the time, such as “freedom”, “justice”, “good”, “truth”, “life”, “happiness”, “individual”, "law,” and so on.
“Every respectable word in philosophy is equivocal by reason”
— Charles DeKoninck
To avoid that mistake, what Aristotle does is take all the key words in philosophy and distinguish the order of their senses. But he’s the only philosopher who does that. Aquinas does it too, but he is following Aristotle, his teacher.
But the moderns do not. Therefore, one can see a lot of confusion in their conversation because of the different senses of a word. If you read them, you will quickly realize there's something like equivocation going on there.
The distinction between the senses of a word is very important in philosophy, which Aristotle and Aquinas emphasize to help us avoid making serious mistakes.