The Fourth Way — Gradation of Being
From degrees of perfection to a maximum that causes them.
Among beings there are some more and some less good, true, noble and the like.
The earlier ways traced change, causal dependence, and contingency. The Fourth Way begins from something we do every day without noticing: we rank things. We call one act kinder than another, one proof more rigorous, one landscape more beautiful. These more and less judgments are the starting point.
Aquinas's claim is that comparison presupposes a standard:
More and less are predicated of different things according as they resemble in their different ways something which is the maximum.
The argument, step by step:
- We find gradations of perfection in things: degrees of goodness, truth, nobility, being.
- To call things more or less of something is to measure them against a maximum: a fullest instance they approach in varying degrees.
- In the things Aquinas has in view, the maximum in a genus is also the cause of that quality in everything else (as fire, the hottest thing, is the source of heat in what is warm).
- Therefore there exists something that is the maximum of being, goodness, and every perfection — and the cause of these in all other things — and this we call God.
A clarification — this is the hardest of the five. Two points clear up the usual objections:
- Aquinas is not talking about degrees on a measuring scale (like temperature in degrees, or height in inches). Those are just quantities. He means qualities like being, goodness, and truth: things that come in degrees but are not tied to any one kind of object.
- Nor is he arguing "because some things are warmer, there must be a warmest thing somewhere." His point in step 3 is that when something has a quality only partly and by sharing in it, that points back to something which is that quality fully and in its own right. What has a quality partially and second-hand points to what has it completely and first-hand.
See it today: the warmth of a room
You do not need a philosophy library to watch this argument work: only to notice how you already speak.
Step into a warm room and you naturally say it is warmer than the hallway, cooler than the oven. Every such judgment is a comparison, and every comparison quietly measures each thing against a fuller case of the same quality. You cannot rank warmth without an idea of heat itself that the warm things possess only in part.
Now shift from heat to the perfections Aquinas actually means:
- You call one friend's act kinder than another's. By what measure? You are comparing both to goodness itself, which each act embodies only partially.
- You call one explanation truer than another. Against what? Truth itself, which every partial account approaches but none exhausts.
- You call one thing more fully realized, more richly being, than a fading or broken one. Against what? Existence held completely, without lack.
Here is the pivot. In each case the things you rank have the perfection — goodness, truth, being — but they only have it; they are not the same as it. Their goodness is partial, mixed, borrowed, and can be more or less. What is had only in degrees, and only by sharing in it, cannot be its own source — any more than warm objects make heat out of nothing. A perfection spread unevenly across many things that merely have it points to one that simply is it — and gives it to the rest.
That fullness of being and goodness itself, from which every lesser and partial good derives, is what we call God.
Where this leads. The other ways ascend through chains of causes; the Fourth Way ascends through a ladder of value and being. Every more good, more true, more real is a rung, and no rung explains itself — each borrows its perfection from higher up. The ladder cannot climb forever on borrowed goodness; it must rest on Goodness that is unborrowed, Being that is unreceived — the maximum that causes all the rest.