Page:Catholic Encyclopedia, volume 5.djvu/208

 DUALISM

170

DUALISM

free wills, and is tolerated by God. Both physical and moral evil are to be conceived as some form of privation or defect of being, not as a positive entity. Their existence is thus not irreconcilable with the doctrine of theistic monism. — Second, the term dual- ism is employed in opposition to monism, to signify the ordinary \-iew that the existing universe contains two radically distinct kinds of being or substance — matter and spirit, body and mind. This is the most frequent use of the name in modern philosophy, where it is commonly contrasted with monism. But it should not be forgotten that dualism in this sense is quite reconcilable with a monistic origin of all things. The theistic doctrine of creation gives a monistic ac- count of the universe in this sense. Dualism is thus opposed to both materialism and idealism. Idealism, however, of the Berkeleyan type, which maintains the existence of a multitude of distinct substantial minds, may, along with dualism, be described as pluralism.

Historically, in Greek philosophy as early as 500 b. c. we find the Eleatic School with Parmenides as their chief, teaching a universal unity of being, thus exhibit- ing a certain affinity with modern German monism. Being alone exists. It is absolutely one, eternal, and unchangeable. There is no real becoming or begin- ning of being. Seeming changes and plurality of be- uigs are mere appearances. To this unity of being Plato opposed an original duality — God and unpro- diiced matter, existing side by side from all eternity. This matter, however, was conceived as indeterminate, chaotic, fluctuating, and governed by a blind neces- sity, in contrast with mind which acts according to plan. The order and arrangement are due to God. Evil and disorder in the world have their source in the resistance of matter which God has not altogether vanquished. Here we seem to have a trace of the Oriental speculation. Again there is another dualism in man. The rational soul is a spiritual substance distinct from the body within which it dwells, some- what as the charioteer in the chariot. Aristotle is dualistic on sundry important topics. The contrast between the fundamental conceptions of matter and form — of a potential and an actualizing principle — runs through all branches of his system. Necessarily coeternal with God, Who is pure actuality, there has e.visted the passive principle of matter, which in this sense, however, is mere potentiality. But further, along with God Who is the Prime Mover, there must also have existed from all eternity the World moved by God. In his treatment of cognition Aristotle adopts the ordinary common-sense view of the exist- ence of individual objects distinct from our percep- tions and ideas of them. Man is an individual sub- stantial being resulting from the coalescence of the two principles — form (the soul) and matter.

Christianity rejected all forms of a dual origin of the world which erected matter, or evil, or any other prin- ciple into a second eternal being coexistent with God; and it taught the monistic origin of the universe from one, infinite, self-existing spiritual Being who freely created all things. The unfamiliar conception of free creation, however, met with considerable opposition in the schools of philosophy and was abandoned by several of the earlier heresies. The neo-Platonists sought to lessen the difficulty by emanastic forms of pantheism, and also by inserting intermediate beings between God and the world. But the former method implied a materialistic conception of God, while the latter only postponed the difficulty. From the thir- teenth century, through the influence of Albertus Magnus and still more of St. Thomas Aquinas, the philosophy of .\ristotle. though subjected to some im- portant modifications, became the accredited philoso- phy of the Church. The dualistic hypothesis of an eternal world existing side by side with God was of cour.se rejected. But the conception of spiritual be- ing as opposed to matter received fuller definition and

development. The distinction between the human soul and the body which it animates was made clearer and their separability emphasized; but the ultra- dualism of Plato was avoided by insisting on the inti- mate imion of soul and body to constitute one substan- tial being under the conception of form and matter.

The problem of dualism, however, was lifted into quite a new position in modern philosophy by Des- cartes (q. v.). Indeed, since his time it has been a topic of central interest in philosophical speculation. His handling of two distinct questions, the one epis- temological, the other metaphysical, brought this about. The mind stands in a cognitional relation to the external world, and in a causal relation to the changes within the body. What is the precise nature of each of these relations? According to Descartes the soul is res cogitans. Its essence is thought. It is simple and unextended. It has nothing in common with the body, but is connected with it in a single point, the pineal gland in the centre of the brain. In contrast with this, the essence of matter lies in exten- sion. So the two forms of being are utterly disparate. Consequently the imion between them is of an acci- dental or extrinsic character. Descartes thus approx- imates to the Platonic conception of charioteer and chariot. Soul and body are really two merely allied beings. How then do they interact? Real reciprocal influence or causal interaction seems impossible be- tween such disparate things. Geulincx and other disciples of Descartes were driven to invent the hy- pothesis of occasionalism and Divine assistance, ac- cording to which it is God Himself who effects the ap- propriate change in either body or mind on the occa- sion of the corresponding change in the other. For this system of miraculous interferences Leibniz sub- stituted the theory of pre-established harmony ac- cording to which God has coupled pairs of bodies and souls which are destined to run in parallel series of- changes like two clocks started together. The same insoluble difficulty of psycho-physical parallelism re- mains on the hands of those psychologists and philos- ophers at the present day who reject the doctrine of the soul as a real being capable of acting on the body which it informs. The ultra-dualism of Descartes was immediately followed on the Continent by the pantheistic monism of Spinoza, which identified mind and matter in one infinite substance of which they are merely "modes".

The cognitional question Descartes solves by a the- ory of knowledge according to which the mind imme- diately perceives only its own ideas or modifications. The belief in an external world corresponding to these ideas is of the nature of an inference, and the guaran- teeing of this inference or the construction of a reliable bridge from the subjective world of thought to the objective world of material being, was thenceforth the main problem of modern philosophy. Locke simi- larly taught that the mind immetliately apprehends only its own ideas, but he assumed a real external world which correspontls to these ideas, at least as re- gards the primary qualities of matter. Berkeley, ac- cepting Locke's assumption that the mind immedi- ately cognizes only its own ideas, raised the question: What grounds have we for belie\'ing in the existence of a material world corresponding to those ideas? He concludes there are none. The external cause of these ideas is God Who awakens them in our minds by regular laws. The dualistic opposition between mind and matter is thus got rid of by denying an independ- ent material world. But Berkeley still postulates a multitude of real substantial minds distinct from each other and apparently from God. We have thus idealistic pluralism. Hume carried Berkeley's scep- ticism a step farther and denied the exist enceof perma- nent spiritual substances, or minds, for grounds simi- lar to those on which Berkeley rejected material sub- stances. All we know to exist are ideas of greater or