neither express its premises nor deduce its conclusions in a scientific manner. Again, theology relies on metaphysics to prove certain truths, called the pre- ambula, which are not revealed but are nevertheless presupposed before revelation can be considered rea- sonable or possiljle. These truths are not the founda- tion on which we rest our supernatural faith. If they should fail, faith would not suffer, though theology should then be rebuilt on another foundation. Fur- thermore, metaphysics, as Aristotle pointed out, cul- minates in the discussion of the existence antl nature of God. God is the object of theology. It is only nat- ural, therefore, that metaphysics and theology should have many points of contact, and that the latter should rely on the former. Finally, since all truth is one, both in the source from which it is derived, and in the subject, the human mind, which it adorns, there must be a kinship between two sciences which, like theology and metaphysics, treat of the most impor- tant conceptions of the human mind. The difference in the manner of treatment, theology relying on reve- lation, and metaphysics on reason alone, does not affect the unity of purpose and the final harmony of the conLlusions of the two sciences.
But, whiie theology thus derives assistance from metaphysics, there can be no doubt that metaph3'sics has derived advantages from its close association with theology. Pre-Christian philosophy failed to arrive at precise metaphysical determinations of the notions of substance and person. This defect was corrected in part by Origen, Clement, and Athanasius, and in part by their successors, the scholastics, the impulse in both cases being given to philosophical definition by the reiiuirements of theological speculation concerning the Blessed Trinity. Pre-Christian philosophy failed to give a coherent, satisfactory account of the origin of the world: Plato's myths and Aristotle's doctrine of the eternity of matter could not long continue to satisfy the Christian mind. It was, once more, the Alexandrian School of Christian metaphysics that, by elaborating the Biblical conception of creation ex nihilo, gave an explanation of the origin of the uni- verse which is satisfactory to the metaphysician as well as to the theologian. Finally, the Catholic doc- trine of Transulistantiation, as discussed by the scho- lastics, gave oi'casion for a more definite and detailed determination of the metaphysical conception of acci- dent in general and of quantity in particular.
VI. The Method of Metaphysics. — Among the objections most frequently urged against metaphys- ics, especially against scholastic metaphysics, is the unscientific character of its method. The metaphysi- cian, we are told, pursues the a priori path of knowl- edge; he neglects or even condemns the use of the a posteriori empirical method which is employed with so much profit in the investigation of nature; he spins, as Bacon says, the threads of his metaphj'sical fabric from the contents of his o^vn mind, as the spider spins her web from the substance of her body, instead of gathering from every source in the world around him the materials for his study, and then working them up into metaphysical principles, as the bee gathers nectar from the flowers and elaborates it into honey. In order to clear up the misunderstanding which under- lies this objection, it is necessary to remark that there are three kinds of method: (1) the a priori, which, as- suming certain self-evident postulates, maxims, and definitions to be true, proceeds deductively to draw conclusions implicatefl in those assumptions; (2) The subjective a posteriori method, which, from an exam- ination of the phenomena of consciousness builds up empirically, that is, inductively, conclusions based on those phenomena; (3) the objective a posteriori method, which l)uilds on the facts of experience in gen- eral in the same way as the subjective method builds on the facts of introspection. "The second method is pre-eminently the method of the Cartesians, who, like
their leader, Descartes, strive to build the whole edi- fice of philosophy on the foundation furnished by re- flection on our thought-processes: Cogito, ergo sum. It is also the method of the Kantians, who, rejecting the psychological basis of metaphysics as unsafe, build on the moral basis, the categorical imperative: their line of reasoning is " I ought, therefore I am free", etc. The third is the method of those who, rejecting the Aristotelean conceptions, essence, substance, cause, etc., substitute so-called empirical conceptions of forccj mass, and so forth, under which they attempt to subsume in a system of empirieo-critical metaphysics the conceptions peculiar to the various sciences.
The first method is admittedly unscientific (in the popular sense of the word) and is adopted only by those philosophers who, like Plato, consider that the true source of philosophical knowlcflge is above us, not in the world around and beneath us. If the for- mula universalia ante rem (see Universals) is taken in the exclusive sense, then we may not look to experi- ence, but to intuition of a higher order of truth, for our metaphysical principles. It is a calumny which originated in ignorance perhaps, more than in preju- dice, that the scholastics followed this a priori method in metaphysics. True, the scholastic philo.sopher, often invokes such principles as " Agere sequitur esse" " Quidquid recipitur per modum recipientis recipitur", etc., and therefrom deduces metaphysical conclusions. If, however, we examine more closely, if we go back from the " Summa", or text-book, where the adage is quoted without proof, to the "Commentary on Aris- totle" where the axiom is first introduced, we shall find that it is proved by inductive or empirical argu- ment, and is therefore, a legitimate premise from which to deduce other truths. In point of fact, the scholastics use a method which is at once a priori and a posteriori, and the latter both in the objective and the subjective sense. In their exposition of truth they naturally use the a priori, or deductive, method. In their investigation of truth they explore empiri- cally both the world of mental phenomena within us, and the world of physical phenomena without us, for the purpose of building up inductively those meta- physical principles from which they proceed. It may be conceded that many of the later scholastics are too ready to invoke authority instead of investigating; it may be conceded, even, that the greatest of the scho- lastics were too dependent on books, especially on Aristotle's works, for their knowledge of nature. But, in principle, at least, the best representatives of scho- lasticism recognized that in philosophy the argument from authority is the weakest argument, and if the cir- cumstances in which they lived and wrote made it im- perative on them to master the contents of Aristotle's writings on natural science, it must, nevertheless, be granted by every fair minded critic that in metaphys- ics at least they improved on the doctrines of the Stagj'rite.
VII. History of Metaphysics. — The history of metaphysics naturally falls into the same divisions as the history of philosophy in general. In a brief out- line of the course which metaphysical spccidation has followed, it will be possible to consider only the prin- cipal stages, namely (1) Hindu philosophy, (2) Greek philosophy, (3) Early Christian philosophy, (4) Medie- val philosophy, (5) Modern philosophy.
(1) Hindu Philosophy. — Of all the peoples of anti(i- uity, the Hindus were the most successful in rising immediately from the mythological explanation of the universe to an explanation in terms of metaphysics. Apparently without passing through the intermediary stage of scientific explanation, they reached at once the heights of the ine(;ipliy>ii:il poinf of view. From polytheism or henothi'i Ml iIhn |himc.i|im| very early to pantheism, and fi-oin tliat Id.-i nnini: lie metaphysi- cal conception of reality. Their stail iiig-point was the realization tliat man is born into a state of bondage