Aquinas’ five ways and other classical arguments for the existence of God

If you want arguments for the existence of God that are totally free of the sort of problems I talked about last week in criticizing Bill O’Reilly, Peter van Inwagen, and design arguments in general, your best bet may be to go back in time two centuries or more. To arguments like those of Thomas Aquinas (1225-1274).

Aquinas’ discussion of God in his most famous work, the Summa Theologiae, begins with five arguments (Aquinas’ famous five ways) for the existence of a “first mover,” “first efficient cause,” a being having necessity of itself, a being which is the cause of every perfection in all other beings, and an intelligent being who directs all other things towards their end.

Aquinas thinks the beings proved by his five arguments are all one and the same, namely God. In the Summa Theologiae he seems to skip arguing this (though if he does have an argument for that claim, it won’t affect anything I’m about to say here). What Aquinas doesn’t skip is giving arguments for many, many claims about what God is like. These claims include that God is good, perfect, powerful, and so on, as well as many less familiar claims.

This is what sets Aquinas’ arguments apart from virtually all arguments for the existence of God made today. Aquinas doesn’t simply ask a question and assume the answer must be God or get to something that sounds kind of like a God and then stop. He avoids those mistakes, as do many of the older writers on the existence of God. For example, Samuel Clarke’s (1675-1729) Discourse Concerning the Being and Attributes of God argues 12 propositions about God one at a time, starting with his existence and ending with the claims that God is all-powerful, infinitely wise, and infinitely good.

However, in spite of these advantages, hardly any believers defend the arguments of people like Aquinas and Clarke. A large part of the answer, I think, is that they relied on assumptions which hardly anyone today shares. It’s worth giving some historical context here, especially for Aquinas.

During the time of the Roman empire, Roman elites were expected to be fluent in both Latin and Greek. So while they had great respect for Greek philosophy, the educated Romans never saw any need to translate Greek philosophical texts into Latin (a fact mentioned, for example, in Cicero’s De Finibus). But as the Roman empire collapsed, knowledge of Greek was lost in the west. Towards the end, a philosopher named Boethius (circa 475-525) decided to translate all of Plato’s and Aristotle’s work into Latin. Unfortunately, he was executed for treason before he could translate more than a few books.

There are many reasons why the centuries following the fall of the Roman empire deserve the name “Dark Ages,” but the loss of virtually all Greek philosophy to the west should be an especially easy one for fans of philosophy to understand. And it’s not surprising that when the rest of Aristotle’s works were finally started being translated into Latin in the 12th century, they were met with great enthusiasm. It’s Aristotle’s philosophy that forms the basis for all of Aquinas’ arguments in the Summa Theologiae, and Aquinas always refers to Aristotle simple as “The Philosopher.”

But today there are very few Aristotelians. That means there are very few of us are moved by arguments with assumptions like this (from the first of Aquinas’ five ways):

For motion is nothing else than the reduction of something from potentiality to actuality. But nothing can be reduced from potentiality to actuality, except by something in a state of actuality. Thus that which is actually hot, as fire, makes wood, which is potentially hot, to be actually hot, and thereby moves and changes it.

Or, here is one of Clarke’s arguments for the proposition “The self-existent being must be intelligent”:

In the order of causes and effects, the cause must always be more excellent than the effect: and consequently the self-existent being, whatever that be supposed to be, must of necessity (being the original of all things) contain in itself the sum and highest degree of all the perfections of all things: not because that which is self-existent must therefore have all possible perfections; (for this, though most certainly true in itself, yet cannot be so easily demonstrated a priori😉 but because it is impossible that any effect should have any perfection, which was not in the cause.

Do we, today, have to take these arguments seriously in spite of their apparently bizarre assumptions? Well no. Here, it’s hard to avoid mentioning (much as I would like to) a Catholic scholar named Ed Feser, who has made a bit of a name for himself complaining about how misunderstood Aquinas is. Among other things, he’s gone after Richard Dawkins for saying, “Would you need to read learned volumes on Leprechology before disbelieving in leprechauns?”

Now I agree that Leprechaunology is not a great analogy for the work of Aquinas or Leibniz. But it’s easy to suggest better analogies: how about Spinozism or Hegelianism? I’d be surprised if Feser took either of those doctrines terribly seriously.

The dirty little secret of philosophy is that just because a philosopher is held up as “great” to the public and considered required reading in undergraduate courses does not mean professional philosophers think his work is very good, or that they’re obliged to study him carefully before thinking his work is not very good.

Feser bemoans this when his colleagues do it to Aquinas, but he himself does it with plenty of modern and contemporary philosophers. The brand of rhetoric that Feser has made his name on strikes many professional philosophers as utterly bizarre, and with good reason.

Note: this post contains partial self-plagiarism from a post written in February 2011. I also wrote it with an eye towards including it in The Book. Unless a regular commenter makes a convincing case to do otherwise, I very much want it to be all I say about Feser there.

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