As we travel through ancient Greek philosophy there are several further important people to consider before arriving at Socrates. The first is Empedocles, who lived in southern Italy in the late 5th century. Russell paints him as quite a character; “philosopher, prophet, man of science and charlatan”. Like Pythagoras he was heavily influenced by Orphism and considered himself partly divine, and like Pythagoras his contribution to science was significant. His most important discovery was that air is a separate substance, which he proved by holding an upside-down bucket under water and showing that it doesn’t fill up. He also demonstrated an example of centrifugal force, by spinning a cup of water at the end of a string and showing that the water doesn’t come out. He knew that the moon shines by reflected light and that light travels, but it is so fast that we cannot detect its movement. He also founded a school of medicine which heavily influenced Plato and Aristotle among others. Like Heraclitus he believed that strife was a constant source of change. The four elements (air, fire, earth & water) were combined in different proportions by love but then separated by strife. Love and strife should be considered as primitive substances similar to the four elements, and it is only these things which are everlasting. There is a cyclical contest between love and strife – one is dominant, then balance, followed by dominance of the other.
The next philosopher Anaxagoras lived in the 5th century, first in Ionia and then in Athens during its golden age (and was expelled from Athens for being an atheist and teaching about ‘things on high’). He made a great contribution to science but did not think much about religion and ethics. He said that everything is infinitely divisible and that even the smallest portion of matter contains some of every element. What we call fire is predominantly fire, but also contains traces of air, earth and water. The exception is mind, which is a substance that only exists in living matter. Mind does not get mixed with other substances, and controls living matter. Mind is uniform; the apparent superiority of human over animal intelligence is due to environmental rather than mental factors. Mind is also the source of motion, but this seems to be in the way of a universal force such as gravity. On cosmology he gave the what is now known to be the correct theory of eclipses, and said that sun and stars are fiery stones, but we don’t feel the heat of the stars because they are too far away.
Atomism was founded by Leucippus and Democritus, who both lived in the late 5th century. It started as an attempt to reconcile the monism of Parmenides and the pluralism of Empedocles. Atomism says that everything is made of atoms which are physically indivisible and indestructible, that atoms are always in random motion, and that between atoms is a void. This was consistent with Parmenides’ view that objects can only move into empty space, so there can only be motion if there is void. The question of whether there can be ‘void’ or empty space occupied the greatest minds through history. Aristotle and Newton asserted the existence of absolute space, but Einstein and quantum theory showed that there is no absolute space. Atoms are Parmenidean in the sense of being constant and unchanging, but they collide with each other to create motion, and join together to create the world around us. However, we should not get over-excited and think that the ancient Greeks invented modern atomic theory. For example, they did not understand chemistry in order to know how atoms bond together. The Atomists believed atoms come in infinite shapes, and when atoms that happen to have interlocking shapes collide, they join together.
Democritus was a pure materialist who did not believe in popular religion. For him even the soul is made of atoms and thought is a physical process. The Atomists were strict determinists who believed everything follows natural laws and fixed mechanical principles. When we ask why an event occurs, we may ask this in two ways. Firstly, what purpose did the event serve, and secondly what earlier circumstances caused the event. The first question is teleological, i.e. it seeks to explain events based on their final purpose (e.g. bread is baked because in the future people will be hungry), and was the method of Socrates, Plato and in particular Aristotle. The Atomists asked the second question, which is mechanistic. Crucially Russell says that the mechanistic question invariable leads to scientific knowledge, whereas the teleological one does not.
Russell believes that a decay began in western thought after Democritus which was not ended until the Enlightenment. This is at first surprising given the eminent Greek thinkers still to come. The earlier Greek philosophers combined a generally scientific approach with unlimited curiosity about the universe. However, sceptics would soon be preoccupied with challenging how we know things rather than acquiring fresh knowledge. Socrates’ focus on ethics was invaluable but did not contribute new scientific knowledge. Plato and Aristotle’s genius came with vices (respectively the rejection of the world of sense for one of pure thought, and the teleological belief in purpose as the fundamental concept in science) which caused enormous harm to future progress. After them came a loss of vigour and independence of thought, partly caused by the victory of Catholic orthodoxy.
Also alive in the late 5th century was Protagoras, who was the most prominent Sophist. This word originally meant teacher or professor. They taught practical skills to the wealthy elite, such as law and oratory (ancient Athens in particular had an addiction to litigation). They taught the art of arguing, and like a modern lawyer were prepared to argue for or against any position. They were less concerned with advocating positions of their own, and for that were criticised and mocked by other thinkers. On the other hand, the Sophists suffered less from bias than later philosophers including Plato. They would follow an argument wherever logic took them, without selecting those which advocated for their existing point of view.