The fourfold division is analogical, not univocal: though the matter, the form, the agent, and the end or purpose, all contribute positively to the production of the effect, it is clear that the character of the causal influence is widely different in each case.
Again, its members do not demand distinct subjects: all four classes of cause may be verified in the same subject. For instance, the human soul is a formal cause in regard to the composite human individual, a material cause in regard to its habits, an efficient cause in regard to its acts, and a final cause in regard to its faculties.
Furthermore, the fourfold division is not an immediate division, for it follows the division of cause in general into intrinsic and extrinsic causes. Finally, it is a division of the causes which we find to be operative in the universe. But the philosophical study of the universe will lead us gradually to the conviction that itself and all the causes in it are themselves contingent, themselves caused by and dependent on, a Cause outside or extrinsic to the universe, a First, Uncaused, Uncreated, Self-Existent, Necessary Cause (Causa Prima, Increata), at once the efficient and final cause of all things. In contrast with this Uncreated, First Cause, all the other causes we have now to investigate are called created or second causes (causae secundae, creatae).
A cause may be either total, adequate, or partial, inadequate, according as the effect is due to its influence solely, or to its influence in conjunction with, or dependence on, the influence of some other cause or causes of the same order. A created cause, therefore, is a total cause if the effect is due to its influence independently of other created causes; though of [pg 364] course all created causes are dependent, both as to their existence and as to their causality, on the influence of the First Cause. Without the activity of created efficient and final causes the First Cause can accomplish directly whatever these can accomplish—except their very causality itself, which cannot be actualized without them, but for which He can supply eminenter. Similarly, while it is incompatible with His Infinite Perfection that He discharge the function of material or formal cause of finite composite things, He can immediately create these latter by the simultaneous production (ex nihilo) and union of their material and formal principles.
A cause is said to be in actu secundo when it is actually exercising its causal influence. Antecedently to such exercise, at least prioritate naturae, it is said to be in actu primo: when it has the expedite power to discharge its function as cause it is in actu primo proximo, while if its power is in any way incomplete, hampered or unready, it is in actu primo remoto.
Many other divisions of cause, subordinate to the Aristotelian division, will be explained in connexion with the members of this latter.
96. Material and Formal Causes.—These are properly subject-matter for Cosmology. We will therefore very briefly supplement what has been said already concerning them in connexion with the doctrine of Change (ch. [ii.]). By a material cause we mean that out of which anything is made: id ex quo aliquid fit. Matter is correlative with form: from the union of these there results a composite reality endowed with either essential or accidental unity—with the former if the material principle be absolutely indeterminate and the correlative form substantial, with the latter if the material principle be some actually existing individual reality and the form some supervening accident. Properly speaking only corporeal substances have material causes,[445] but the term “material cause” is used in an extended sense to signify any potential, passive, receptive subject of formative or actuating principles: thus the soul is the subjective or material cause of its faculties and habits; essence of existence; genus of differentia, etc.
In what does the positive causal influence of a material cause consist? How does it contribute positively to the actualization of the composite reality of which it is the material cause? It receives and unites with the form which is educed from its potentiality by the action of efficient causes, and thus contributes to the generation of the concrete, composite individual reality.[446]
It is by reason of the causality of the formal cause that we speak of a thing being formally such or such. As correlative of material cause it finds its proper application in reference to the constitution of corporeal things. The formative principle, called forma substantialis, which actuates, determines, specifies the material principle, and by union with the latter constitutes an individual corporeal substance of a definite kind, is the (substantial) formal cause of this composite substance.[447] The material principle of corporeal things is of itself indifferent to any species of body; it is the form that removes this indefiniteness and determines the matter, by its union with the latter, to constitute a definite type of corporeal substance.[448] The existence of different species of living organisms and different types of inorganic matter in the universe implies in the constitution of these things a common material principle, materia prima, and a multiplicity of differentiating, specifying, formative principles, formae substantiales. That the distinction between these two principles in the constitution of any individual corporeal substance, whether living or inorganic, is not merely a virtual distinction between metaphysical (generic and specific) grades of being in the individual, but a real distinction between separable entities, is a scholastic thesis established in the Special Metaphysics of the organic and inorganic domains of the universe.[449]
Since the form is a perfecting, actuating principle, the term is often used synonymously with actus, actuality. And since besides the essential perfection which a being has by virtue of its substantial form it may have accidental perfections by reason of supervening accidental forms, these, too, are formal causes.