Looked at from the side of the agent that undergoes it, this influence is a passive yielding: this next becomes an active motion of appetite; and in the case of free will a deliberate act of intending the end, followed by acts of choosing means, and finally by acts commanding the executive faculties to employ these means.
Looked at from the side of the final cause, the influence consists in an attraction of appetite towards union with itself as a good. The matter cannot be analysed much further; nor will imagination images help us here any more than in the case of efficient causality. It must be noted, however, that the influence of the final cause is the influence not of a reality as actual, or in its esse actuale, but of a reality as present to a perceiving mind, or in its esse intentionale. At the same time it would be a mistake to infer from this that the influence of the final cause is not real. It is sometimes described as “intentional” causality, “causalitas intentionalis”; but this must not be taken to mean that it is not real: for it is not the “esse intentionale” of the good, i.e. the cognition of the good, its presence in the mind or consciousness of the agent, that moves the latter's appetite: it is the apprehended good, apprehended as real, as possible of actual attainment, that moves the agent to act. The influence may not be physical in the sense of being productive of, or interchangeable with, or measurable by, corporeal energy, or in terms of mechanical work; nor is it; but it is none the less real.
But if the influence of a final cause really reaches to the effect of the agent's actions only through the medium of the latter's appetite, and therefore through a link of “intentional” causality, does it not at once follow that the attribution of final causality to the domain of unconscious and inorganic activities, can be at best merely metaphorical? The attribution to such agencies of an “appetitus naturalis” is intelligible indeed as a striking and perhaps not unpoetic metaphor. But to contend that it is anything more than a metaphor, to claim seriously that inanimate agencies are swayed and influenced by “ends,”—is not this really to substitute mysticism and mystery for rational speculation and analysis?
Mechanists are wont to dismiss the doctrine of final causes in the physical universe with offhand charges of this kind. They are but too ready to attribute it to a mystical attitude of mind. Final causes, they say, are not discovered in inanimate nature by the cold, calculating, unemotional analysis to which reason submits its activities, but are read into it by minds which allow themselves to be prompted by the imagination and emotions to personify and anthropomorphize inanimate agencies. The accusation is as plausible as it is unjust. It is plausible because the attribution of final causes to inanimate nature, and of an “appetitus naturalis” to [pg 414] its agencies, seems to imply the recognition of conscious, mental, “intentional” influence in this domain. But it really implies nothing of the sort; and hence the injustice of the charge. What it does imply is the existence of a genuine analogy between the nature and natural activities of physical agencies on the one hand and the appetite and appetitive activities of conscious agencies on the other. The existence of this analogy is absolutely undeniable. The orderly, invariable and uniformly suitable character of physical activities, simply forces our reason to recognize in physical agencies natures which tend towards their development, and which by their activities attain to what is good for them, to what perfects them. In other words we have to recognize that each by its natural line of activity attains to results that are good and useful to it just as if it apprehended them as such and consciously tended towards them. The analogy is there; and the recognition of it, so far from being a “mystic” interpretation of facts, is an elementary logical exercise of our reasoning faculty. The scholastics emphasized their recognition of the analogy by calling the nature of an unconscious agent,—the principle of its active tendencies towards the realization of its own perfection—an “appetitus naturalis”: an expression into which no one familiar with scholastic terminology would venture to read any element of mysticism.[505]
Every separate agency in nature has a uniform mode of activity; by following out this line of action each co-operates with all the others in maintaining the orderly course of nature. These are facts which call for explanation. They are not explained by the supposition of mechanists that these agencies are mere efficient causes: efficient causality does not account for order, it has got simply nothing to do with order or regularity. Consequently the last word of the mechanical philosophy on the fact of order in the universe is—Agnosticism. In opposition to this attitude we are far from contending that there is no mystery, or that all is clear either in regard to the fact of change or the fact of regularity. Just as we cannot explain everything in efficient causality, so neither can we explain everything in final causality. But we do contend that the element of order, development, evolution, even in the physical universe, can be partially explained [pg 415] by recognizing in its several agencies a nature, a principle of development, a passive inclination implanted in the very being of these agencies by the Intelligent Author of their being.
In conscious agencies this inclination or tendency to actions conformable or connatural to their being is not always in act; it is aroused by conscious cognition, perception, or imagination of a good, and operates intermittently. In unconscious agencies it is congenital and constantly in act, i.e. as a tendency, not as actually operative: for its actual development due conditions of environment are required: the seed will not grow without a suitable soil, temperature, moisture, etc. In conscious agencies the tendency, considered entitatively or as a reality in them, is an accidental form; in unconscious agencies it is their forma substantialis, the formative substantial principle, which determines the specific type to which their nature belongs.[506]
In all agencies the inclination or appetite or tendency to action arises from a form; an elicited appetite from an “intentional” form, a natural appetite from a “natural” form: Omnis inclinatio seu appetitus consequitur formam; appetitus elicitus formam intentionalem, appetitus naturalis formam naturalem. The scholastic view that final causality pervades all things is expressed in the aphorism, Omne agens agit propter finem: Every agency acts for an end.
From our analysis of final causality it will be seen that the “end” becomes a cause by exercising its influence on the agent or efficient cause, and thus initiating the action of the latter. We have seen already that material and formal causes exercise their causality dependently on the efficient cause of the change or effect produced by the latter. We now see that the final cause, the end as intended, determines the action of the efficient cause; hence its causality holds the primacy as compared with that of the other causes: it is in this sense the cause of causes, causa causarum.[507] But while the end as intended is the starting point of [pg 416] the whole process, the end as attained is the ultimate term of the latter. Hence the scholastic aphorism: Finis est primus in intentione et ultimus in executione. And this is true where the process involves a series of acts attaining to means subordinate to an end: this latter is the first thing intended and the last attained.
The final cause, the end as intended, is extrinsic to the effect. It is intrinsic to the efficient cause. It is a “forma” or determinative principle of the latter: a forma intentionalis in conscious agents, a forma naturalis in unconscious agents.
109. Nature and the Laws of Nature. Character and Grounds of their Necessity and Universality. Scientific Determinism and Philosophic Fatalism.—By the term nature we have seen that Aristotle and the scholastics meant the essence or substance of an agent regarded as inner principle of the latter's normal activities, as determining the bent or inclination of these, and therefore as in a real sense their final cause. Hence Aristotle's definition of nature as a certain principle or cause of the motion and rest of the thing in which that principle is rooted fundamentally and essentially and not merely accidentally.[508] The scholastics, recognizing that this intentio naturae, this subjection to finality, in unconscious agencies must be the work and the index of intelligence, in other words that this analogical finality in inanimate things must connote a proper finality, a properly purposive mode of action, in the author of these things, conceived this nature or intentio naturae as the impression of a divine art or plan upon the very being of all creatures by the Creator Himself. Hence St. Thomas's profound and well-known description of nature as “the principle of a divine art impressed upon things, in virtue of which they move towards determinate ends”. Defining art as the just conception [pg 417] of external works to be accomplished,[509] he observes that nature is a sort of art: “as if a ship-builder were to endow his materials with the power of moving and adapting themselves so as to form or construct a ship”.[510] And elsewhere he remarks that nature differs from art only in this that the former is an intrinsic, the latter an extrinsic, principle of the work which is accomplished through its influence: so that if the art whereby a ship is constructed were intrinsic to the materials, the ship would be constructed by nature as it actually is by art.[511]