ARGUMENTS FOR THEISM Theism, being a reflective theory and not simply a religious faith, has sought to defend its position by rational arguments. Historically, three arguments have been supremely important and are sometimes known as the "traditional proofs." They are the Cosmological, the Teleological, and the Ontological arguments.
The first philosopher, at least in the West, to state an argument which he held to be demonstrative of the existence of God is Plato. The proof which he gives (in the Laws X.) is the starting point of the rational theology or "natural" theology which claims to establish the being of God on the ground of reason. The Laws is universally admitted to be the work of Plato's old age. In his earlier writings Plato had made use of the idea of God and indeed the conception was central in his thought. He had constantly pro tested against unworthy ideas of the divine and asserts both in the Republic and Theaetetus that God is perfectly good and cannot be the cause of evil. The proof in the Laws may be regarded as the fruit of long reflection on the problem and contains the germ of much subsequent development. The proof turns upon the existence of motion and change. Motions and changes may be divided into several classes, but there is one fundamental distinc tion, that between spontaneous and communicated motion. It can be shown that spontaneous motion must be prior to communicated motion, since if there is motion at all it cannot all be com municated. Now the soul is the source of spontaneous motion, as distinguished from matter which can only receive communicated motion. Hence the soul is prior to the body. The motions in the Universe which have no human origin must likewise be referred to a soul. We are thus led to the conception of a Soul of the world. But the motions of the Universe, and in particular of the heavenly bodies, are orderly and thus indicate that the World Soul is rational and good, the "mind which ordered the universe." In Plato's argument two of the "rational" proofs are joined— the Cosmological (from the existence of a universe in which motion exists to a Source of motion), and the Teleological (from the existence of order to the Divine Mind as its ground). It will be convenient to consider these arguments in their subsequent formulations separately.
is not, like that of Plato, profoundly religious in spirit, and the concept of God in Aristotle's thought has little religious sig nificance, being mainly a metaphysical conclusion ; but the formu lation of the cosmological argument by Aristotle has been of primary importance for Christian philosophy. Like his master Plato, Aristotle rises to the thought of God from the fact of change and motion (Kivnats) which means for him much more than change of place. Motion is conceived by Aristotle as the passage from potentiality to actuality (bviamts and ivEp-yela). Every change which actually occurs is the realization of a poten tiality which was hitherto latent. Associated with this conception is Aristotle's doctrine of "form" and "matter." Every concrete and finite existence is composed of matter and form and it is the latter which gives to it a specific nature. In "sublunary" existences the expression of form is always imperfect, the matter never being absorbed in the form completely. The motion and change of the world are therefore explained as the striving of the potential to become actual, of the forms to become fully realised. The universe which is in constant motion is not, however, self-explana tory; the change must have some source beyond itself. This source is God, who must be conceived as at once the First Mover and the Unmoved. There can be nothing higher than God, other wise He himself would be moved towards that higher being. God must exist or there would be no movement. God is therefore pure form and pure actuality, in Him there is no "matter" and no potentiality. He is the realization of all form and of all poten tiality. Thus God moves the world 4.) 'epeop,Evoli, as an object of desire; but it is an essential part of Aristotle's view that God does not desire or need the world. The world is not even known to Him as it exists in actuality. He contemplates the pure forms which are the content of His own intellect. The outcome of Aristotle's reflection is then a Deity who is completely trans cendent and pure thought. All personal relations with the world, every trace of emotion and even moral goodness is excluded from his nature which is described as a thinking of thought (vOnats volloews) (Aristotle, Physics, Bk. VIII., Metaphysics, Bk. XII.).