Socrates is not considered a Pre-Socratic philosopher because he lived and taught in the 5th century BCE, while the Pre-Socratic philosophers were active in the 6th and 7th centuries BCE.

Thales believed that all things are made up of a single substance, which he called water. He argued that water is the source of all life and that it is the underlying principle of all reality.

Anaximander believed that the origin of all things is the Boundless, an infinite and indeterminate substance. He argued that the Boundless is the source of all opposites, such as hot and cold, wet and dry, and light and dark.

Heraclitus believed that all things are in a state of constant flux and that opposites are actually complementary. He argued that the world is a unity of opposites, such as day and night, life and death, and good and evil.

Democritus believed that reality is composed of atoms and the void. He argued that atoms are indivisible, indestructible, and homogeneous particles that move through the void, which is an infinite and empty space.

The Pre-Socratic philosophers laid the foundation for the study of knowledge by asking fundamental questions about the nature of reality, the origin of the universe, and the possibility of human knowledge. Their ideas and arguments have had a profound impact on the development of epistemology, the branch of philosophy that studies the nature of knowledge.

Heraclitus argued that the senses are unreliable because they are constantly changing. He believed that the only true reality is the Logos, or the underlying order of the universe, which can only be understood through reason.

Parmenides believed that reality is one and unchanging. He argued that change and multiplicity are illusions and that the only true reality is the One, which is perfect, eternal, and immutable.

Zeno's paradoxes are a series of logical arguments that challenge the idea of motion. They show that if motion is real, then it must lead to a number of contradictions. Zeno's paradoxes have had a profound impact on the development of philosophy and mathematics.

Empedocles argued that knowledge is based on experience and that the senses are a reliable source of information. He believed that all things are composed of four elements: earth, air, fire, and water. He also developed a theory of evolution that suggested that living things have evolved from simpler forms over time.

Anaxagoras believed that the mind is the source of all motion and change in the universe. He argued that the mind is a pure and unmixed substance that is separate from matter. He also developed a theory of atomism that suggested that all things are composed of tiny particles called seeds.

Leucippus and Democritus believed that the universe is composed of atoms and the void. They argued that atoms are indivisible, indestructible, and homogeneous particles that move through the void, which is an infinite and empty space. They also developed a theory of atomism that suggested that all things are composed of atoms.

The Pre-Socratic philosophers laid the foundation for the study of knowledge by asking fundamental questions about the nature of reality, the origin of the universe, and the possibility of human knowledge. Their ideas and arguments have had a profound impact on the development of Western philosophy and have shaped the way we think about the world today.

Anaxagoras argued that the universe is governed by a rational order, which he called the Nous. He believed that the Nous is a pure and unmixed substance that is responsible for the organization and harmony of the universe. He also developed a theory of atomism that suggested that all things are composed of tiny particles called seeds.

The Pre-Socratic philosophers believed that the senses are the source of all knowledge. They argued that we can only know what we can experience through our senses. This view is known as empiricism.