3. The Good
a) Formation of the theory. With the good, as with the
true, St. Thomas found a twofold tradition, the Platonist
and the Aristotelian. According to the Platonist conception,
which was to persist in the Augustinian school, the good is
to be understood as a transcendent principle, existing apart
from the material world. Given this premise, it was more
or less inevitable that the Platonists should also hold the
good to be prior and hence pre-eminent to being. The
Aristotelian tradition, in line with its more realist orientation,
takes the more familiar view, conceiving of the good
as a perfection inherent to the things of experience. St.
Thomas' contribution, again, would be one of synthesis;
specifically, it was to be an accommodation of Platonist
tenets to the Aristotelian scheme of the good.
b) Nature of the good. At the beginning of the Nicomachean Ethics Aristotle, in a well-known context, defines (or rather endorses the definition of) the good as that toward which all things tend: quod omnia appetunt - literally, "what all things desire." 27 Thus the basic thing about the good is that it bears on (and stirs) the appetite. If, as we have seen, the true denotes a relation of intellect to being, the good for its part denotes a relation of being to the appetite - statements which but give philosophical expression to matters of common and indeed universal experience. But whereas the true resides primarily in the faculty of knowledge, the good lies basically in the thing; is, as a matter of fact, the thing itself considered as founding the property of appetibility.
That every being has the nature of good, or that the good is a transcendental St. Thomas establishes in the following manner. The good is what all things desire; but a thing is desired according as it is perfect; it is perfect, however, so far as it is in act; and it is in act in the measure that it is being. Conclusion (which necessarily follows): good and being are the same reality. But they are not the same in thought or concept; for the good conveys the formality of appetibility, which is not explicitly said when we say "being." St. Thomas gives all this in the following passage:
Goodness and being are really the same, and differ only in idea; which is clear from the following argument. The essence of goodness consists in this, that it is in some way desirable. Hence the Philosopher says: Goodness is what all desire [Eth. 1,1, 1094 a 3]. Now it is clear that a thing is desirable only in so far as it is perfect, for all desire their own perfection. But everything is perfect so far as it is actual. Therefore it is clear that a thing is perfect so far as it is being; for being is the actuality of every thing, . . . Hence it is clear that goodness and being are the same really. But goodness expresses the aspect of desirableness, which being does not express.28
Act, perfection, good: three aspects of being with meanings which, though not identical, are nevertheless so closely related that the thought of one suggests the thought of the other(s). And since in reality they are the same as being, it necessarily follows that being and good are convertible 29
c) The good as final cause.30 Another related notion of the good is that of final cause. Clearly, whatever a thing desires as final cause can only be a good for it; conversely, every good can assume the formality of final cause. "Since the good," in the words of St. Thomas, "is that which all things desire, and since this has the aspect of an end, it is clear that goodness implies the aspect of an end" [i.e. final cause].31 In short, the order of good coincides with that of finality - a self-evident truth once we know the meaning of "good" and "final cause."
It is also true that final causality does not act in isolation; it implies both efficient and formal causality, the formal as principle of the efficient. Nevertheless, the causality proper to the good precisely as good is final causality, which consists in evoking desire. Hence it is along the line of final causality that we must understand the accepted expression that "good is self-diffusing" (or "self-radiating"): bonum est diffusivum sui. The diffusion or radiation is not to be taken literally, like the emission of light from a body; which is to say it is not an activity of efficient causality. But, it might be asked, does not final cause or the good (it is all the same) have the status of an unmoved mover; and if so, does not this indicate an exercise of efficient causality? The answer is that they are indeed unmoved movers, but only when they are strictly themselves, i.e. only so far as they determine and govern the activity of the appetite.
d) Kinds of good. Since good is convertible with being its concept, like that of being, will be analogical; and for every particular being there will be a corresponding good. According to a classical division, which goes back to St. Ambrose, good is of three kinds: the perfective, the useful, and the pleasing (or satisfying) good.32 Correctly understood this division is exhaustive. Good is the object of the appetite, or that which is desired. But what is desired is either a means to a further end, or it is itself the desired end. If the desired good is a means, it falls under the useful: bonum utile. If, on the other hand, the good is itself the desired end, two points of view emerge. Either the good in question refers to the object in which the movement of the appetite terminates, giving us the perfective good: bonum honestum - or it designates the subjective possession of this same object, the "quiescence upon attaining the desired thing," and thus is the pleasing good: bonum delectabile. There is no good that does not fit this classification. But we must not, among other things, read too much into the notion of "perfective good," which is not necessarily the all-perfect good (though that is included) but any good in which the appetite comes to rest. Even so, good in the primary sense is the perfective good, to which the useful is related as means and the pleasing as complement. The pleasing good, moreover, refers properly to beings endowed with affectivity (i.e. intellectual and/or sensory appetition) but is attributed analogically to other beings as well.
e) Evil: the opposite of good. Evil is a many-sided problem, far too complex to do it justice here. We should, however, - and that is all we intend - state the general position of St. Thomas as to the nature (loosely speaking) of evil, a position which follows logically from his conception of its opposite, the good. Opposites, as St. Thomas observes, can generally be known one through the other, as darkness through light. Evil, then, will be known from the nature of good. Now good is convertible with being; hence every being has the nature of good. Thus evil, the opposite of good, cannot be a positive being; it can only refer to some absence of being, (which means) of good.
It is impossible [concludes St. Thomas] that evil signify any being, or any form or nature. Therefore, by the name evil must be signified some absence of good. And this is what is meant by saying that evil is neither a being nor a good. For since being, as such, is good, the absence of being involves the absence of good."
However, not just any absence answers to the meaning of evil; it has to be the absence of a modality of being which, considering the nature of a thing, should be present - so, to be wingless is not an evil for man but would be (say) for a robin. In formal idiom such an absence is a privation: the lack of a due perfection (as is commonly put). An immediate deduction from this is that absolute evil is impossible; for, presupposing as it does a subject, evil always rests on something positive, which, because it is being, cannot but be good. Perhaps not so evident but just as true is that evil cannot be desired for its own sake, or precisely as evil. An appetite must always bear on what is (or presents itself as) good; and if it seems to be directed toward evil, this on examination will prove to be either an apparent or an incidental evil: the appetite is seeking a good to which some evil attaches. In short, only the good has the nature and aspect of desirability: solum bonum habet rationem appetibilis.
Appendix: The principle of finality In the volume on the philosophy of nature (cosmology) we had occasion to speak of finality under the causes of mobile being.34 But finality, it should be noted, operates not only within the area of nature; it is rooted in being universally, has therefore a metaphysical basis; which is the reason for returning to the subject now. A final cause (to proceed metaphysically) corresponds to a good; conversely, every good has the nature or formality of an end. This was made clear some paragraphs back. We have also seen that a being can only act for (which is to say, desire) a good; its every assertion, its every tendency is for a good, and if a good then an end. And this, in effect, is what the principle of finality says, that "every agent acts for an end": omne agens agit propter finem. This principle can be substantiated in several different ways, and on different levels of thought. But the basic reason why there must be an end for every action is the metaphysical reason that potency cannot determine itself. If there is to be action from an agent in potency, this potency must be determined, and determined to some definite thing. Now, it is all the same whether we say an agent is determined to some definite thing, or that the agent is acting for an end. St. Thomas gives this train of thought in these (much the same) words:
An agent does not move except out of intention for an end. For if the agent were not determined to some particular effect, it would not do one thing rather than another. Consequently, in order that it produce a determinate effect it must, of necessity, be determined to some certain one, and this will have the nature of an end.35
Thus, what comes into play here is, once again, the cardinal thesis of metaphysics that potency stands in essential (transcendental) relation with act, or (same thought) that potency is determined by act.
One further remark. Like any metaphysical principle, that of finality is analogical, true of all beings but in proportion to their nature, as St. Thomas in the above-mentioned context goes on to show.36 Finality in inanimate beings is one thing, for they do not move themselves to the end but are moved. Significantly different, yet not wholly, is the like exercise in rational beings, who know and move themselves to the end. But greatest of all is the incumbent adjustment of the principle when said of the Deity; for God, properly speaking, does not act out of desire of the end - this would imply a want of goodness - but only from love of the end that is his own infinite goodness.37