The henological argument, Aquinas’ fourth way, is so called because in it we reason from multiplicity to unity (hen, unum) - from goodness, truth, reality in the various forms in which experience makes them known to us, to a Being who is the Good, the True, the Real. Its scope is to show that the limited and partial manifestations of these perfections compel us to admit the existence of a Being in whom they find their complete realization - that multiplicity and imperfection are wholly inexplicable apart from unity and perfection - and finally that the One and Perfect is, in fact, a Personal God.
Aquinas states the argument thus:
“The fourth way is taken from the gradation to be found in things. Among beings there are some more and some less good, true, noble and the like. But "more" and "less" are predicated of different things, according as they resemble in their different ways something which is the maximum, as a thing is said to be hotter according as it more nearly resembles that which is hottest; so that there is something which is truest, something best, something noblest and, consequently, something which is uttermost being; for those things that are greatest in truth are greatest in being, as it is written in Metaph. ii. Now the maximum in any genus is the cause of all in that genus; as fire, which is the maximum heat, is the cause of all hot things. Therefore there must also be something which is to all beings the cause of their being, goodness, and every other perfection; and this we call God.”
To understand this argument, it may be helpful to recall what we discussed earlier regarding the ten categories. The ten basic categories designate modes of being. The first is substance, and other nine are quantity, quality, relation, location, time, disposition (the arrangement of parts), rainment (being clothed, armed, etc.), action, and passion. These are the basic or ultimate groups into which real entities may be classified. Each category contains some particular generic or specific attribute or “perfection”. They express either the substantial nature of a being or some quantity, quality, relation, etc. belonging to it.
But perfections (attributes) such as reality, goodness, truth, unity, beauty, and the like, are perfections that are applied in all the categories equally. The application of them is not confined to any special part, be it genus or differentia of nature. There is no nature and no part of any nature of which they may not be predicated. The animality and the rationality of Socrates are both real just as his qualities, quantity, etc. Humanity is a good thing as is strength or size due to a human body or the relation of fatherhood. One and all of these things can be objects of intellectual knowledge. Therefore, they are true. Because attributes such as goodness, truth, reality, etc. transcend the limits that restrict all other perfections to one or another of the categories, they are called transcendentals.
Two important consequences flow from the transcendental nature of these special perfections. First, the transcendentals do not connote any limitation or imperfection. Any attribute which is by its very nature restricted to a particular category inevitably involves imperfection because it is essentially finite. But the transcendentals do not imply any category. Rather, a transcendental such as goodness goes beyond or transcends the limits imposed by a category. The apple pie that I made is good, but the pie made by my mother is better. The goodness of each apple pie is predicated according as they resemble in their different ways something which is the maximum in “goodness”.
Second, transcendentals are analogous and not univocal. A generic or specific attribute is univocal. It has the same signification in all the subjects of which it is predicated. The notion or concept it expresses is always identically the same. Thus the term ‘animal’ denotes precisely the same characteristics whether used to describe a human or an insect. So far as this term is applied to them, the differences of the two classes, however fundamental, do not come under consideration.
It is not the same with analogous terms. The concepts which these terms signify are not identically but proportionally the same. The goodness of a man is not identical with the goodness of a horse nor can the goodness of each be expressed by a concept which remains the same as applied to each of them. Yet they are proportionately similar. A good man and a good horse are each seen as having that which constitutes the perfection of their respective natures. In the goodness of a man, the requisite qualities are moral. In the goodness of a horse, the requisite qualities are physical.
Now when the same attribute, in this case “goodness”, is found in a plurality of individuals, it is impossible that the attribute can belong to each of them in its own right and in virtue of its being the particular thing it is. Even if there were only two such entities, either the one must have received it from the other, or both must owe the attribute to a cause outside them and of a higher order.
This follows from a metaphysical principle we discussed in Aquinas’ third way. Wherever we have a union of diverse elements, that union postulates a cause. In the third way, we dealt with the case of the combination of different elements in one concrete thing. Here we are dealing with the combination of different individual entities in a single class. The individuals that form the class of Man, are in virtue of their individuality utterly distinct. But their common nature makes them specifically (not numerically) one – and a series of propositions can be framed regarding the abstract subject Man which can be verified of every individual in the class.
We cannot explain this unity apart from a common cause. We cannot say that each member of the class is a man in virtue of his being himself, and because he is the distinct individual which he is. Things are not united by the very thing through which they differ. The principle of diversity is not and cannot be the principle of unity. Individuality is the principle of diversity. It follows that a perfection held in common must have been received from another. And because diversity will never account for unity, we must conclude that there is a single cause to which the common perfection must be referred.
It is sufficient here to note that, as Aristotle points out, there can be no such thing as an immaterial essence of a material nature. Matter is part and parcel of the essence of such things. An immaterial essence of a horse or of a tree, subsisting as an individual separate thing, is a sheer contradiction in terms. However, such natures can exist apart from matter as concepts of the mind – I can think of a horse in my mind – the horse in my mind while not having material existence still does have the nature of a horse – but unlike the material horse the one in my mind has no existence outside my mind. I couldn’t plow my field with the horse in my mind.
Transcendental perfections, however, are different. Matter is no necessary part of their essence. 'Being' or 'goodness,' considered in their essential nature, involve no limit, no imperfection. The concept of goodness as such expresses goodness in an infinite degree. If we desire to conceive a finite and restricted goodness we must ourselves introduce the note of limit. It is true that, as we have experience only of finite things, our knowledge of goodness is necessarily of a goodness which is limited. But this does not affect the significance of the term. For the transcendentals are analogous - the terms expressing them signify the transcendentals themselves, but do not connote the particular mode in which they are found in this or that subject.
Returning to the metaphysical principle discussed previously, we know that the perfections of being, goodness and truth, as they are known to us in experience, must, as we have seen, be referred to a single cause of a higher order. Now, when we were considering material essences, we recognized that this immaterial higher cause could not be something of the same specific nature, since such a nature can only be found upon the plane of material existence. The higher cause which confers a material perfection must be of an altogether different kind. It must, indeed, somehow contain the perfection which it confers, or it could not give it. But it contains it eminently and not formally.
As regards transcendental perfections the case is otherwise. Goodness and reality are not perfections proper to a lower plane of being. Here there is no question of a cause which only contains the perfection which it gives, eminently. Goodness and reality will be found formally in the cause producing them. The cause of goodness will itself be good: the cause of reality will be real; though the mode in which these perfections belong to it will not be identical with, but analogous to, the same perfections as found in its effects.
In fact, it should be clear that the cause must be the perfection itself as a subsistent entity. The formal cause of goodness will not be something that possesses goodness, nor is it identical with goodness. In such cases, it would be composed of diverse elements and we would need to seek the cause outside it. It must be none other than subsistent Goodness.
This subsistent Goodness – goodness itself – absolute goodness – is not restricted to some particular mode. It is goodness in its fullness, i.e. infinite goodness. For it must be a goodness which has no cause higher than itself, and it follows of necessity that the goodness with which we are dealing knows no limits.
Pure goodness is absolutely simple (not composite) and is uncaused. But pure goodness is as the same time real. Thus it is not just uncaused goodness but uncaused being – not possessing being but is being. Therefore, it is infinite being as well as infinite goodness.
The same arguments can be made of any other transcendental – truth, unity, intelligence, will, etc.
In such manner each transcendental becomes identical with one another, coalescing into one simple infinite Being. This infinite Being is manifestly what we signify by the name of God.
