Western Philosophy

C

The Heraclitean School

Heraclitus of Ephesus, who was active around 500 bc, continued the search of the Ionians for a primary substance, which he claimed to be fire. He noticed that heat produces changes in matter, and thus anticipated the modern theory of energy. Heraclitus maintained that all things are in a state of continuous flux, that stability is an illusion, and that only change and the law of change, or Logos, are real. The Logos doctrine of Heraclitus, which identified the laws of nature with a divine mind, developed into the pantheistic theology of Stoicism. (Pantheism is the belief that God and material substance are one, and that divinity is present in all things.)

D

The Eleatic School

In the 5th century bc, Parmenides founded a school of philosophy at Elea, a Greek colony on the Italian peninsula. Parmenides took a position opposite from that of Heraclitus on the relation between stability and change. Parmenides maintained that the universe, or the state of being, is an indivisible, unchanging, spherical entity and that all reference to change or diversity is self-contradictory. According to Parmenides, all that exists has no beginning and has no end and is not subject to change over time. Nothing, he claimed, can be truly asserted except that “being is.” Zeno of Elea, a disciple of Parmenides, tried to prove the unity of being by arguing that the belief in the reality of change, diversity, and motion leads to logical paradoxes. The paradoxes of Zeno became famous intellectual puzzles that philosophers and logicians of all subsequent ages have tried to solve. The concern of the Eleatics with the problem of logical consistency laid the basis for the development of the science of logic.

E

The Pluralists

The speculation about the physical world begun by the Ionians was continued in the 5th century bc by Empedocles and Anaxagoras, who developed a philosophy replacing the Ionian assumption of a single primary substance with an assumption of a plurality of such substances. Empedocles maintained that all things are composed of four irreducible elements: air, water, earth, and fire, which are alternately combined and separated by two opposite forces, love and strife. By that process the world evolves from chaos to form and back to chaos again, in an eternal cycle. Empedocles regarded the eternal cycle as the proper object of religious worship and criticized the popular belief in personal deities, but he failed to explain the way in which the familiar objects of experience could develop out of elements that are totally different from them. Anaxagoras therefore suggested that all things are composed of very small particles, or “seeds,” which exist in infinite variety. To explain the way in which these particles combine to form the objects that constitute the familiar world, Anaxagoras developed a theory of cosmic evolution. He maintained that the active principle of this evolutionary process is a world mind that separates and combines the particles. His concept of elemental particles led to the development of an atomic theory of matter.

F

The Atomists

It was a natural step from pluralism to atomism, the theory that all matter is composed of tiny, indivisible particles differing only in simple physical properties such as size, shape, and weight. This step was taken in the 4th century bc by Leucippus and his more famous associate Democritus, who is generally credited with the first systematic formulation of an atomic theory of matter. The fundamental assumption of Democritus’s atomic theory is that matter is not infinitely divisible but is composed of numerous indivisible particles that are too small for human senses to detect. His conception of nature was thoroughly materialistic (focused on physical aspects of matter), explaining all natural phenomena in terms of the number, shape, and size of atoms. He thus reduced the sensory qualities of things, such as warmth, cold, taste, and odor, to quantitative differences among atoms—that is, to differences measurable in amount or size. The higher forms of existence, such as plant and animal life and even human thought, were explained by Democritus in these purely physical terms. He applied his theory to psychology, physiology, theory of knowledge, ethics, and politics, thus presenting the first comprehensive statement of deterministic materialism, a theory claiming that all aspects of existence rigidly follow, or are determined by, physical laws.

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G

The Sophists

Toward the end of the 5th century bc, a group of traveling teachers called Sophists became famous throughout Greece. The Sophists played an important role in developing the Greek city-states from agrarian monarchies into commercial democracies. As Greek industry and commerce expanded, a class of newly rich, economically powerful merchants began to wield political power. Lacking the education of the aristocrats, they sought to prepare themselves for politics and commerce by paying the Sophists for instruction in public speaking, legal argument, and general culture. Although the best of the Sophists made valuable contributions to Greek thought, the group as a whole acquired a reputation for deceit, insincerity, and demagoguery. Thus the word sophistry has come to signify these moral faults.

The famous maxim of Protagoras, one of the leading Sophists, that “man is the measure of all things,” is typical of the philosophical attitude of the Sophist school. Protagoras claimed that individuals have the right to judge all matters for themselves. He denied the existence of an objective (demonstrable and impartial) knowledge, arguing instead that truth is subjective in the sense that different things are true for different people and there is no way to prove that one person’s beliefs are objectively correct and another’s are incorrect. Protagoras asserted that natural science and theology are of little or no value because they have no impact on daily life, and he concluded that ethical rules need be followed only when it is to one’s practical advantage to do so.

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