Politics and ethics must be resolved to metaphysics. The subject matter of political or ethical science is not properly metaphysical; yet, as all the lower sciences are resolved to metaphysics, so must politics and ethics be resolved. The subject matter of the natural sciences (i.e. physics and biology) is not properly a metaphysical subject matter; yet all things are metaphysically constituted, so even the object signified by the subject matter of physics may be studied metaphysically, considered under a different formality. E.g. man may be studied as an object of natural science insofar as he is a being of matter and motion; he may be studied as an object of metaphysics insofar as he is simply a being. Object and subject-matter are not synonymous: the same object (a being) may be studied by two different sciences, insofar as those sciences relate to it under distinct formalities, constituting it as a different logical subject matter for each science.
Political science is not the same as metaphysics, for it has a different subject-matter and a different goal: it studies not being as being, but human action as such; yet insofar as human action is related to being, as such it does indeed pertain to metaphysics. This is not to identify politics with metaphysics, but to resolve politics to principles which can only be provided by metaphysics. The political or ethical philosopher knows how to act as man only because he knows what is the perfection of man’s being – the good by which his being expresses and fulfills itself. Meta-physics knows man as being, as a participant in being as such; consequently it knows what his perfection is, insofar as it knows being as such in relation to what is the perfection of being as such: the good itself. Metaphysics is the search for the causes of being as such: knowledge of the perfection of being is knowledge of its final cause. This, indeed, is how Aristotle culminates his pursuit of the metaphysical science.
Man is a being, because man exists; but he is man because his existence is conditioned and lim-ited by a certain mode of being, an essence, which is a peculiar potency with respect to the act that is existence, which together make him a being. Being is not univocal; it is analogous. Thus, although metaphysics differs from the lower sciences by considering being as such, it can only know being in its unity by simultaneously assimilating and separating from its knowledge of the particular modes of being. Metaphysics assimilates the particular and limited knowledge that has particular modes of being for its object, e.g. the knowledge gained by the natural sciences. This knowledge is not properly metaphysical, nor is metaphysical knowledge the same as natural science; yet natural science is resolved to metaphysics, and metaphysics must assimilate the knowledge gained by natural science – these are in fact the converse of each other. The study of human nature as one particular mode of being, a mode of being that is one-of-a-kind and not uni-vocally being with respect to (for example) mere physical being, is one such category of knowledge that can and must be assimilated and resolved to metaphysical knowledge. Accordingly, the theoretical study of human nature against the backdrop of which alone ethics and politics are possible is indeed relevant to metaphysics, and must be shown to receive its principles from metaphysics. Conversely, metaphysical knowledge itself is perfected in the degree that the metaphysician knows human nature as such in being as such.
Knowing metaphysically what is the ultimate final cause of being, and knowing in relation to being what is the nature of the human being in particular, the philosopher may transition from speculative to practical intellect: the question for the practical philosopher, having transitioned from metaphysics, becomes how to attain the final cause of being, and more specifically, the final cause of the human being. These questions are related, because ultimately the final cause of being and the final cause of human being are the same thing: and the answer to the latter question can only be resolved in relation to the former. Ultimately, the perfection of man is only a moment, a stage, granted a highly significant stage, of the perfection of all being in the divine final cause of all things.
Metaphysics reveals what is the perfection of man, which is hierarchically manifold and ultimately one. Ethics and politics reveal what are the practical steps that a human being and a human society might take in order to attain that perfection. The ethicist and politician cannot perform their philosophical task without metaphysics: only through metaphysics do they know what is the perfection they seek; and they even gain remarkable insight into the ontological nature of the steps that must be taken, since metaphysics reveals not merely the ultimate goal, but also the intermediate goals, the many stages of metaphysical goodness and perfection in respect to being. Just as the perfection of man is itself an intermediate stage within a whole structure of perfections ordered to the ultimate final cause, so there are many intermediate stages between man’s proper perfections and the perfection enshrined in the ultimate final cause. Philosophical anthropology, especially one that is metaphysically guided, has much to say on the many kinds and grades of human perfection: perfection of his lower, middle, and highest faculties; the participation of his lower faculties in his higher faculties; the participation of his higher faculties in a mode of operation that is not even properly human (i.e. angelic operation); the various relations of his faculties to lesser and greater objects, i.e. external goods. Etc. Speculative or theoretical philosophy reveals not only the Good, but the goods of being, and of specific kinds of beings, and of human beings. To the ethicist, this store of theoretical wisdom becomes a guidebook, a map of goods to be acquired, of choices to be made, etc. He takes this wisdom and applies in the infinitesimal circumstance; he unites the universal principle with the contingent situation of factual, historical existence. He teaches and practices the virtue of prudence.