Aristotle’s Metaphysics: Substance, Form, and Knowledge
Ultimately, the primary substance is the truly real, the substance in the strict sense: it is the ultimate subject in which all other things have their existence. Following Plato, Aristotle considers the nature of a thing—what makes it what it is—to be its form, not its matter. Aristotelian forms, like Platonic Ideas, possess a qualitative nature. However, unlike Platonic Ideas, which are transcendent and exist above the world of sensible things, Aristotelian forms are intrinsic to things themselves. What truly exists, according to Aristotle, are individual beings (primary substances); universal ideas or forms (secondary substances) do not exist independently but are mental concepts formed through abstraction. For these reasons, Aristotle’s philosophy is considered realistic (intellectual realism), in contrast to Platonic idealism.
E. Method of Knowledge: Abstraction
For Aristotle, to do science, one must start by analyzing the concrete things surrounding humans and subject to empirical perception. The first object of knowledge is concrete, immediate, singular reality: substance. He distinguishes two sources of knowledge: sensitivity and understanding. Sense knowledge, a vital human function, captures real qualities through sensory perception, storing them in memory. Aristotle emphasizes sensitivity more than Plato. However, knowledge is not limited to sensory perception. Sensible forms are not the ultimate knowable aspect of things; their essence can also be known. Here, the second capacity, understanding, comes into play, capturing the essence of things. Understanding has two functions: First, as patient understanding, it engenders universal concepts conceived from the essence. It is not enough that the essence is intelligible; the understanding must conceive universal concepts. The second function is to illuminate the essence of things, making it intelligible. Its role is to understand the concept; this is the intellect. Understanding, based on experience, identifies the sensible forms of various things and proceeds inductively to form a universal concept. However, grasping the universal implicit in the particular requires a superior power: intuition. Empirical and rational knowledge are complementary, with the former leading to the latter. For Aristotle, the essence of things is the form, captured by patient understanding and illuminated by the intellect, separating it from its matter. This mentally conceived universal concept can be predicated of all things with the same ontological structure. From this arises science, the highest level of knowledge.
4. Physics or Second Philosophy
To develop theoretical scientific knowledge, one should begin by investigating the world of concrete, sensible things. This first scientific knowledge is called second philosophy or physics. In the sensible world, a distinction exists between natural and artificial things. Natural things possess an internal principle or nature that is both the essence and cause of their movement and transformation. Natural beings develop and transform according to their nature and purpose. This interpretation of nature is known as teleological, meaning each thing moves toward its proper perfection. Natural things include: plants (birth, nourishment, growth, reproduction); animals (the above functions, plus sensation, desire, and locomotion); and humans (animal functions, plus reason and intellect). Artificial things are created and modified by extrinsic principles. For Aristotle, movement is evident; the task is to explain it. Aristotle’s physics overcomes Eleatic aporia and emphasizes the fallacy of Parmenides’ arguments. Against the concept of a unique Being, Aristotle maintains a pluralism of Being: there is a unique Being, but many beings or forms of being exist. Compared to Parmenides’ concept, Aristotle defends its analogical character:“Being is said in many ways” Thus, we have:
- Two ways of being: ontological being (real individual beings that change) and logical being (concepts developed by intelligence).
- Two modes of non-being: absolute non-being (what is not and cannot be) and relative non-being (what is not but can be).
- Two aspects of Being: being in potency (potential) and being in act (actual).
Against the static nature of being, Aristotle defends the possibility of movement with his theory of potency and act: What moves is not Being itself, but specific entities and individuals. Movement is not the passage from absolute non-being to absolute being, but from potency to act. Thus, movement is real and a subject of science. Aristotle also distinguishes between mathematical and physical being, addressing the Eleatic paradoxes. Mathematical and physical infinity must be distinguished; while mathematical infinity is possible, physical infinity is not. Once the evidence of movement is established, it must be explained. Aristotle addresses three issues: the elements involved in change, the types of changes, and the causes of change.