Physics

Physics

Physics has for its object the study of "being intrinsically endowed with motion", in other words, the study of nature. For nature differs from art in this: that nature isessentially self-determinant from within, while art remains exterior to the products of art. In its self-determination, that is to say in its processes, nature follows anintelligent and intelligible form. "Nature is always striving for the best". Movement is a mode of being, namely, the condition of a potential being actualizing itself. There are three kinds of movement: quantitative (increase and decrease), qualitative (alteration) and spatial (locomotion). Space is neither matter nor form, but the "first and unmoved limit of the containing, as against the contained". Time is the measure of the succession of motion. In his treatment of the notions of motion, space, andtime, Aristotle refutes the Eleatic doctrine that real motion, real space, and realsuccession imply contradictions. Following Empedocles Aristotle, also, teaches that all terrestrial bodies are composed of four elements or radical principles, namely: fire, air, earth, and water. These elements determine not only the natural warmth or moisture of bodies, but also their natural motion, upward or downward, according to the preponderance of air or earth. Celestial bodies are not constituted by the four elements but by ether, the natural motion of which is circular. The Earth is the centre of the cosmic system; it is a spherical, stationary body, and around it revolve the spheres in which are fixed the planets. The First Heaven, which plays so important a part in Aristotle's general cosmogonic system, is the heaven of the fixed stars. It surrounds all the other spheres and, being endowed with intelligence, it turned toward the Deity, drawn, as it were, by His Desirability, and it thus imparted to all the other heavenly bodies the circular motion which is natural to them. Thesedoctrines, as well as the general concept of nature as dominated by design or purpose, came to be taken for granted in every philosophy of nature down to the time of Newton and Galileo, and the birth of modern physical science.
Psychology in Aristotle's philosophy is treated as a branch of physical science. It has for its object the study of the soul, that is to say, of the principle of life. Life is the power of self-movement, or of movement from within. Plants and animals, since they are endowed with the power of adaptation, have souls, and the human soul is peculiar only in this, that to the vegetative and sensitive faculties, which characterize plant-life and animal life respectively it adds the rational faculty--the power of acquiring universal and intellectual knowledge. It must therefore be borne in mind that when Aristotle speaks of the soul he does not mean merely the principle of thought; he means the principle of life. The soul he defines as the form, actualization, or realization of the body, "the first entelechy of the organized bodypossessing the power of life". It is not a substance distinct from the body, as Platotaught but a co-substantial Principle with the body, both being united to form the composite substance, man. The faculties or powers of the soul are five-fold: nutritive, sensitive, appetitive, locomotive, and rational. Sensation is defined as the faculty "by which we receive the forms of sensible things without the matter, as the wax receives the figure of the seal without the metal of which the seal is composed". It is "a movement of the soul", the "form without the matter" being the stimulus which calls forth that movement. The typos, as that form is called, while it is analogous to the "effluxes" about which the Atomists spoke, is not like the efflux, a diminished object, but a mode of motion, mediating between the object and the faculty. Aristotle distinguishes between the five external senses and the internal senses, of which the most important are the Central sense and the Imagination.Intellect (nous) differs from the senses in that it is concerned with the abstract anduniversal, while they are concerned with the concrete and particular. The naturalendowment of intellect is not actual knowledge, but merely the power of acquiringknowledge. The mind "is in the beginning without ideas, it is like a smooth tablet on which nothing is written". All our knowledge, therefore, is acquired by a process of elaboration or development of sense-knowledge. In this process the intellect exhibits a two-fold phase an active and a passive. Hence it is customary to speak of the Active and Passive Intellect, though it is by no means clear what Aristotle meant by these concepts. The corruption of the text in some of the most critical passages of the work "On the Soul"--the mixture of Stoic pantheism, in the explanation of the earlier commentators, not to speak of the later addition of extraneous elements on the part of the Arabian, Scholastic, and modern transcendentalist expounders of the text--have rendered it impossible to say precisely what meaning to attach to the terms Active and Passive Intellect. It is enough to remark here that:

• according to the Scholastics Aristotle understood both Active and PassiveIntellect to be parts, or phases, of the individual mind;
• according to the Arabians and some earlier commentators, the first of these, perhaps, being Aristocles, he understood the Active Intellect to be a divine something, or at least something transcending the individual mind;
• according to some interpreters the Passive Intellect is not properly anintellectual faculty at all, but merely the aggregate of sensations out of whichideas are made, as the statue is made out of the marble.

From the fact that the soul in its intellectual operations attains a knowledge of the abstract and universal, and thus transcends matter and material conditions, Aristotle argues that it is immaterial and immortal. The will, or faculty of choice, is free, as isproved by the recognized voluntariness of virtue, and the existence of reward and punishment.