Ethics or Moral Philosophy (ἤθος, mos, mores, morals, conduct) is that department of practical philosophy which has for its subject-matter all human acts, i.e. all acts elicited or commanded by the will of man considered as a free, rational and responsible agent. And it studies human conduct with the practical purpose of discovering the ultimate end or object of this conduct, and the principles whereby it must be regulated in order to attain to this end. Ethics must therefore analyse and account for the distinction of right and wrong or good and bad in human conduct, for [pg 012] its feature of morality. It must examine the motives that influence conduct: pleasure, well-being, happiness, duty, obligation, moral law, etc. The supreme determining factor in all such considerations will obviously be the ultimate end of man, whatever this may be: his destiny as revealed by a study of his nature and place in the universe. Now the nature of man is studied in Psychology, as are also the nature, conditions and effects of his free acts, and the facilities, dispositions and forms of character consequent on these. Furthermore, not only from the study of man in Psychology, but from the study of the external universe in Cosmology, we amass data from which in Natural Theology we establish the existence of a Supreme Being. We then prove in Ethics that the last end of man, his highest perfection, consists in knowing, loving, serving, and thus glorifying God, both in this life and in the next. Hence we can see how these branches of speculative philosophy subserve the practical science of morals. And since a man's interpretation of the moral distinctions—as of right or wrong, meritorious or blameworthy, autonomous or of obligation—which he recognizes as pertaining to his own actions—since his interpretation of these distinctions is so intimately bound up with his religious outlook and beliefs, it is at once apparent that the science of Ethics will be largely influenced and determined by the system of speculative philosophy which inspires it, whether this be Theism, Monism, Agnosticism, etc. No doubt the science of Ethics must take as its data all sorts of moral beliefs, customs and practices prevalent at any time among men; but it is not a speculative science which would merely aim at a posteriori inferences or inductive generalizations from these data; it is a practical, normative science which aims at discovering the truth as to what is the right and the wrong in human conduct, and at pointing out the right application of the principles arising out of this truth. Hence it is of supreme importance for the philosopher of morals to determine whether the human race has really been vouchsafed a Divine Revelation, and, convincing himself that Christianity contains such a revelation, to recognize the possibility of supplementing and perfecting what his own natural reason can discover by what the Christian religion teaches about the end of man as the supreme determining principle of human conduct. Not that he is to take the revealed truths of Christianity as principles of moral philosophy; for these are the principles of the supernatural [pg 013] Christian Theology of human morals; but that as a Christian philosopher, i.e. a philosopher who recognizes the truth of the Christian Revelation, he should reason out philosophically a science of Ethics which, so far as it goes, will be in harmony with the moral teachings of the Christian Religion, and will admit of being perfected by these. This recognition, as already remarked, will not be a hindrance but a help to him in exploring the wide domains of the individual, domestic, social and religious conduct of man; in determining, on the basis of theism established by natural reason, the right moral conditions and relations of man's conduct as an individual, as a member of the family, as a member of the state, and as a creature of God. The nature, source and sanction of authority, domestic, social and religious; of the dictate of conscience; of the natural moral law and of all positive law; of the moral virtues and vices—these are all questions which the philosopher of Ethics has to explore by the use of natural reason, and for the investigation of which the Christian philosopher of Ethics is incomparably better equipped than the philosopher who, though possessing the compass of natural reason, ignores the beacon lights of Divinely Revealed Truths.

Esthetics, or the Philosophy of the Fine Arts, is that department of philosophy which studies the conception of the beautiful and its external expression in the works of nature and of man. The arts themselves, of course, whether concerned with the realization of the useful or of the beautiful, are distinct from sciences, even from practical sciences.[13] The technique itself consists in a skill acquired by practice—by practice guided, however, by a set of practical canons or rules which are the ripe fruit of experience.[14] But behind every art there is always some background of more or less speculative truth. The conception of the useful, however which underlies the mechanical arts and crafts, is not an ultimate conception calling for any further analysis than it receives in the various special sciences and in metaphysics. But the conception of the beautiful does seem to demand a special philosophical consideration. On the subjective or mental side the esthetic sense, artistic taste, the sentiment of the beautiful, the complex emotions accompanying such experience; on the objective side the elements [pg 014] or factors requisite to produce this experience; the relation of the esthetic to the moral, of the beautiful to the good and the true—these are all distinctly philosophical questions. Up to the present time, however, their treatment has been divided between the other departments of philosophy—psychology, cosmology, natural theology, general metaphysics, ethics—rather than grouped together to form an additional distinct department.

V. Departments of Speculative Philosophy: Metaphysics.—The philosophy which studies the order realized in things apart from our activity, speculative philosophy, has been variously divided up into separate departments from the first origins of philosophical speculation.

When we remember that all intellectual knowledge of things involves the apprehension of general truths or laws about these things, and that this apprehension of intelligible aspects common to a more or less extensive group of things involves the exercise of abstraction, we can understand how the whole domain of speculative knowledge, whether scientific or philosophical, can be differentiated into certain layers or levels, so to speak, according to various degrees of abstractness and universality in the intelligible aspects under which the data of our experience may be considered. On this principle Aristotle and the scholastics divided all speculative knowledge into three great domains, Physics, Mathematics and Metaphysics, with their respective proper objects, Change, Quantity and Being, objects which are successively apprehended in three great stages of abstraction traversed by the human mind in its effort to understand and explain the Universal Order of things.

And as a matter of fact perhaps the first great common and most obvious feature which strikes the mind reflecting on the visible universe is the feature of all-pervading change (κίνησις), movement, evolution, progress and regress, growth and decay; we see it everywhere in a variety of forms, mechanical or local change, quantitative change, qualitative change, vital change. Now the knowledge acquired by the study of things under this common aspect is called Physics. Here the mind abstracts merely from the individualizing differences of this change in individual things, and fixes its attention on the great, common, sensible aspect itself of visible change.

But the mind can abstract even from the sensible changes that take place in the physical universe and fix its attention on a static feature in the changing things. This static element [pg 015] (τὸ ἀκίνητον), which the intellect apprehends in material things as naturally inseparable from them (ἀκίνητον ἀλλ᾽ οὐ χωριστόν), is their quantity, their extension in space. When the mind strips a material object of all its visible, sensible properties—on which its mechanical, physical and chemical changes depend—there still remains as an object of thought a something formed of parts outside parts in three dimensions of space. This abstract quantity, quantitas intelligibilis—whether as continuous or discontinuous, as magnitude or multitude—is the proper object of Mathematics.

But the mind can penetrate farther still into the reality of the material data which it finds endowed with the attributes of change and quantity: it can eliminate from the object of its thought even this latter or mathematical attribute, and seize on something still more fundamental. The very essence, substance, nature, being itself, of the thing, the underlying subject and root principle of all the thing's operations and attributes, is something deeper than any of these attributes, something at least mentally distinct from these latter (τὸ ἀκίνητον και χωριστόν): and this something is the proper object of man's highest speculative knowledge, which Aristotle called ἡ πρώτη φιλοσοφία, philosophia prima, the first or fundamental or deepest philosophy.[15]

But he gave this latter order of knowledge another very significant title: he called it theology or theological science, ἐπιστήμη θεολογίκή, by a denomination derived a potiori parte, from its nobler part, its culmination in the knowledge of God. Let us see how. For Aristotle first philosophy is the science of being and its essential attributes.[16] Here the mind apprehends its [pg 016] object as static or abstracted from change, and as immaterial or abstracted from quantity, the fundamental attribute of material reality—as ἀκίνητον καὶ χωριστόν. Now it is the substance, nature, or essence of the things of our direct and immediate experience, that forms the proper object of this highest science. But in these things the substance, nature, or essence, is not found in real and actual separation from the material attributes of change and quantity; it is considered separately from these only by an effort of mental abstraction. Even the nature of man himself is not wholly immaterial; nor is the spiritual principle in man, his soul, entirely exempt from material conditions. Hence in so far as first philosophy studies the being of the things of our direct experience, its object is immaterial only negatively or by mental abstraction. But does this study bring within the scope of our experience any being or reality that is positively and actually exempt from all change and all material conditions? If so the study of this being, the Divine Being, will be the highest effort, the crowning perfection, of first philosophy; which we may therefore call the theological science. “If,” writes Aristotle,[17] “there really exists a substance absolutely immutable and immaterial, in a word, a Divine Being—as we hope to prove—then such Being must be the absolutely first and supreme principle, and the science that attains to such Being will be theological.”

In this triple division of speculative philosophy into Physics, Mathematics, and Metaphysics, it will naturally occur to one to ask: Did Aristotle distinguish between what he called Physics and what we nowadays call the special physical sciences? He did. These special analytic studies of the various departments of the physical universe, animate and inanimate, Aristotle described indiscriminately as “partial” sciences: αἱ ἐν μέρει ἐπιστημάι—ἐπιστημαὶ ἐν μέρει λεγόμεναι. These descriptive, inductive, comparative studies, proceeding a posteriori from effects to causes, he conceived rather as a preparation for scientific knowledge proper; this latter he conceived to be a synthetic, deductive explanation of things, in the light of some common aspect detected in them as principle or cause of all their concrete characteristics.[18] Such synthetic knowledge of things, in the light of some such common aspect as change, is what he regarded as scientific knowledge, meaning thereby what we mean by philosophical [pg 017] knowledge.[19] What he called Physics, therefore, is what we nowadays understand as Cosmology and Psychology.[20]

Mathematical science Aristotle likewise regarded as science in the full and perfect sense, i.e. as philosophical. But just as we distinguish nowadays between the special physical and human sciences on the one hand, and the philosophy of external nature and man on the other, so we may distinguish between the special mathematical sciences and a Philosophy of Mathematics: with this difference, that while the former groups of special sciences are mainly inductive the mathematical group is mainly deductive. Furthermore, the Philosophy of Mathematics—which investigates questions regarding the ultimate significance of mathematical concepts, axioms and assumptions: unity, multitude, magnitude, quantity, space, time, etc.—does not usually form a separate department in the philosophical curriculum: its problems are dealt with as they arise in the other departments of Metaphysics.