Ancient Philosophy

Pre-Socratics

Atomists

The philosophy of atomism was established by two individuals—Leucippus and Democritus. They are often mentioned together, making it difficult to distinguish between them; indeed, some of Leucippus's works were likely later attributed to Democritus.

Leucippus, whose active period appears to have been around 440 BCE, hailed from Miletus and continued the scientific rationalist philosophy associated with that city. He was significantly influenced by Parmenides and Zeno. Little is known about him, to the point that Epicurus (a later follower of Democritus) even suggested the possibility that Leucippus never existed, a theory some modern scholars have revived. However, there are several references to him in Aristotle's works, making it implausible that these citations (which include textual quotations) would exist if Leucippus were merely a mythical figure.

Democritus, in contrast, is a much more defined character. He was born in Abdera, Thrace; regarding the time of his life, he mentions that Anaxagoras was already an old man during his youth, approximately around 432 BCE. The peak of Democritus’s activity is estimated around 420 BCE. In his quest for knowledge, Democritus undertook extensive journeys to southern and eastern lands; it is possible that he spent a significant amount of time in Egypt and undoubtedly visited Persia. He later returned to Abdera, where he remained. Zeller asserts that Democritus "surpassed all philosophers—both his predecessors and contemporaries—in the richness of knowledge, and most of them—in the sharpness and logical correctness of thought."

Democritus was a contemporary of Socrates and the sophists, and chronologically, he should be considered somewhat later in the history of philosophy. However, the situation is complicated by the difficulty of distinguishing between Democritus and Leucippus. On this basis, I place him before Socrates and the sophists, even though his philosophy was partially intended to serve as a response to his fellow countryman Protagoras, the most renowned sophist. Protagoras was enthusiastically received when he visited Athens, while Democritus laments, "I came to Athens, and no one recognized me." For a long time, his philosophy was ignored in Athens. "It is unclear," says Barnett, "whether Plato knew anything about Democritus... Aristotle, on the other hand, was well-acquainted with Democritus, for he too was an Ionian from the North." Plato never mentions Democritus in his dialogues, but as Diogenes Laertius notes, Plato hated Democritus so much that he wished for all his books to be burned. His work is highly regarded, particularly his contributions to mathematics.

The foundational ideas of the shared philosophy of Leucippus and Democritus can be traced back to the former, though it is hardly possible to distinguish between them in terms of their development. Furthermore, for our purposes, it is unlikely to find merit in attempting to do so. The attempt to establish a middle ground between the monism of Parmenides and the pluralism of Empedocles led Leucippus, if not Democritus, toward atomism. The perspective of Leucippus and Democritus was remarkably similar to that of modern science and devoid of many of the flaws to which Greek speculative thought was prone. They posited that all things are composed of atoms, indivisible physically but not geometrically; that there exists empty space between atoms; that atoms are indestructible; that they have always been and will always be in motion; and that there is an infinite number of both atoms themselves and their varieties, differing in shape and size. Aristotle asserts that, according to the atomists, atoms also differ in warmth. Spherical atoms, from which fire is composed, are the hottest. As for weight, Aristotle cites Democritus, who states, "each of the indivisible [bodies] is heavier due to its greater size." However, whether atoms were endowed with weight from the outset in the atomists' theories remains a matter of debate.

Atoms are always in motion, but commentators disagree about the nature of the initial motion of the atoms. Some, particularly Zeller, argue that atoms were conceived as eternally falling, with heavier atoms falling faster than lighter ones; thus, they would catch up with lighter atoms and collide with them, causing the atoms to deviate from their paths, much like billiard balls. Epicurus undoubtedly adhered to this view, basing many of his theories on those of Democritus, while rather foolishly attempting to account for Aristotle's criticism. However, there is significant reason to believe that Leucippus and Democritus did not consider weight as an inherent property of atoms. It seems more likely that, according to their view, atoms initially moved randomly, akin to the modern kinetic theory of gases. Democritus asserted that in infinite emptiness, there is neither up nor down and likened the movement of atoms in the soul to the motion of specks of dust in a sunbeam when there is no wind. This view is considerably more reasonable than Epicurus's, and I believe we can accept it as undeniably characteristic of Leucippus and Democritus.

As a result of collisions, clusters of atoms form vortices. The subsequent events largely unfold as in Anaxagoras's account. The advancement lies in the fact that vortices are explained more by mechanical causes than by the action of the mind.

The ancient world commonly reproached the atomists for attributing everything to chance. On the contrary, they were strict determinists. They believed that everything occurs according to natural laws. Democritus explicitly denied that anything could happen by chance. Leucippus, though his existence is questioned, is known for his one saying: "Nothing comes into being without a reason; rather, everything arises on some basis and out of necessity." It is true that he did not explain why the world should have initially been as it is; perhaps this should be attributed to chance. But once the world exists, its further development is invariably determined by mechanical principles. Aristotle and others criticized Leucippus and Democritus for failing to provide an explanation for the cause of the initial motion of atoms, but in this regard, the atomists were more scientific than their critics. Causality must have a beginning, and wherever it begins, one cannot point to a cause of the initial given. The cause of the existence of the world may be attributed to a Creator, but then the Creator himself would remain uncaused. The atomists' theory is, in fact, closer to modern science than any other theory proposed in antiquity.

Unlike Socrates, Plato, and Aristotle, the atomists sought to explain the world without resorting to the concept of purpose or final cause. The "final cause" of a given process is an event in the future for which the process unfolds. In human affairs, this notion is entirely applicable. Why does a baker bake bread? Because otherwise, people will be hungry. Why are railroads built? Because people wish to travel. In such cases, things are explained in terms of the goals they serve. When we ask why a certain event occurs, we may mean one of two things. We might imply, "What purpose does this event serve?" or we could be referring to "What earlier circumstances caused this event?" The answer to the first question is a teleological explanation, or an explanation through a final cause; the answer to the latter question is a mechanistic explanation. I do not know how it could have been predetermined which of these two questions science ought to pose or whether it should pose both questions simultaneously. But experience has shown that the mechanistic question leads to scientific knowledge, while the teleological question does not. The atomists posed the mechanistic question and provided a mechanistic answer. Their successors, up to the Renaissance, were more interested in the teleological question, thus leading science into a dead end.

Both questions have equal limits that are often ignored in everyday thinking and in philosophy. One cannot reasonably pose any question regarding reality as a whole (including God), but only about its parts. As for teleological explanations, following them, we typically arrive at a Creator or at least an Artificer, whose purposes are realized through the development of nature. However, if a person is so obstinate in their teleological thinking that they continue to ask what purpose the Creator himself serves, it becomes evident that their question is impious. Moreover, it is nonsensical, as to give it meaning, we must presume that the Creator himself was created by some Super-Creator, whose purposes he serves. The concept of purpose, therefore, applies only to phenomena within reality, but not to reality as a whole.

The same argument applies to mechanistic explanations. One event causes another, which in turn causes a third, and so forth. However, if we inquire about the cause of the whole, we again arrive at a creator who himself must be without cause. Therefore, any causal explanation must ultimately have an arbitrary beginning that lacks a cause. This is why it cannot be considered a deficiency in the atomic theory that it leaves the initial movement of atoms unexplained.

It should not be assumed that the atomists based their theories solely on empirical grounds. The atomic theory was revived in the modern era to explain the facts of chemistry; however, these facts were not known to the Greeks. In antiquity, there was no clear distinction between empirical observation and logical proof. It is true that Parmenides regarded observed facts with disdain, but Empedocles and Anaxagoras linked much of their metaphysics to observations of water clocks and rotating buckets. Before the Sophists, it seems, no philosopher doubted that a complete metaphysics and cosmology could be created by combining a large number of arguments with some observations. By a fortunate accident, the atomists stumbled upon a hypothesis for which, more than two thousand years later, some grounds would be found, yet at that time their doctrine was nonetheless devoid of any firm foundation.

Like many philosophers of his time, Leucippus sought a way to reconcile the arguments of Parmenides with the evident fact of motion and change. Aristotle remarks: “Thus, and for such reasons, statements were made about the truth. In reasoning, this appears coherent; however, in reality, such views approach madness. For there is no person so mad as to believe that fire and ice are the same; only among beautiful things and those that appear beautiful by habit do some, in their madness, see no distinction.”

Leucippus believed he had arguments that aligned with sensory perception and did not deny the emergence or destruction of things, nor the motion or plurality of the existing. In this, he agreed with the given phenomena, and with those who posited the doctrine of the One, he concurred, asserting that motion cannot exist without void, that void is non-being, and that nothing existing is non-being. For truly existent things constitute a complete being. Yet it is not one; rather, it is an infinite multitude of particles, invisible due to their minuscule size. They move through the void (for void exists) and, when they combine, bring about emergence, and when they separate, cause destruction. They act and are acted upon to the extent that they happen to come into contact with one another, for at that point they are no longer one. Their union and interweaving lead to the emergence of things, while from the truly One, multitude could not arise, just as from the truly Many, the One could not arise. This is impossible.

We shall observe that there was one point on which all have thus far agreed, namely, that motion is impossible in the absence of void. In this, they were all equally mistaken. Circular motion in filled space is possible on the condition that it has always existed. The idea was that a thing can move only in empty space, whereas filled space contains no empty places. It may be objected, and likely quite reasonably, that motion can never arise in filled space, but it cannot be justifiably asserted that it cannot occur there at all. To the Greeks, however, it seemed that one must either acknowledge Parmenides’ unchanging world or concede the existence of void.

Parmenides’ arguments against non-being appear logically irrefutable concerning void, and they were supported by the discovery that where, evidently, nothing exists, there is air. (This is an example of a widespread chaotic mingling of logic and observation.) We can articulate Parmenides’ position as follows: “You say that void exists; therefore, void is not nothing; hence, it is not void.” It cannot be said that the atomists responded to this argument; they simply proclaimed their preference to ignore it on the grounds that motion is a fact of perception. Therefore, there must be void, however difficult it may be to conceive.

Let us consider the subsequent history of this question. The first and most obvious way to resolve the logical difficulties was to differentiate between matter and space. According to this perspective, space is not nothing but a receptacle that may or may not be filled with matter in any given part. Aristotle states (Physics, 208a): “Those asserting the existence of void call it place; in this sense, void would be a place devoid of body.” This viewpoint is expressed with utmost clarity by Newton, who asserted the existence of absolute space and correspondingly distinguished absolute motion from relative motion. In the Copernican dispute, both sides (however little they understood it) adhered to this viewpoint, believing there to be a difference between the assertion “the heavens rotate from east to west” and the assertion “the earth rotates from west to east.” If all motion is relative, then these two statements are merely different ways of expressing the same thing, akin to the statements “John is the father of James” and “James is the son of John.” But if all motion is relative and space is non-substantial, then only Parmenides’ arguments remain against void.

Descartes, whose arguments closely align with the positions of early Greek philosophers, stated that extension is the essence of matter, and therefore, matter exists everywhere. For him, extension is an adjective rather than a noun; its noun is matter, and without its noun, extension cannot exist. To him, empty space is as absurd as happiness without a sentient being that is happy. Leibniz, starting from somewhat different grounds, also believed that only filled space exists, but he claimed that space is merely a system of relations. This led to the famous dispute between Leibniz and Newton, with the latter being represented by Clarke. The dispute remained unresolved until Einstein, whose theory ultimately brought victory to Leibniz.

While contemporary physicists believe that matter is, in some sense, atomic, they no longer believe in empty space. Where there is no matter, there is still something, if only light waves. Matter no longer holds the exalted position it acquired in philosophy through Parmenides’ arguments. It is no longer an immutable substance but merely a way of grouping events. Some events belong to groups that can be regarded as material things; others, such as light waves, do not belong to these groups. The stuff of the world consists of events, each characterized by transience. In this respect, modern physicists side with Heraclitus against Parmenides. Yet they were on the side of Parmenides until Einstein and quantum theory emerged on the scene.

Concerning space, the contemporary view holds that it does not constitute a substance, as Newton asserted and as Leucippus and Democritus were compelled to assert; nor is space merely an adjective of extended bodies, as Descartes believed. Instead, it represents a system of relations, as Leibniz contended. Nonetheless, it remains unclear whether this perspective is compatible with the existence of void. It may be that, in abstract logical terms, one could reconcile it with emptiness. We might say that between any two things exists a certain greater or lesser interval, and this interval does not imply the existence of intermediate bodies. However, such a viewpoint would be untenable in modern physics. Since Einstein, the interval has become the distance between events rather than between objects, characterized as much by temporality as by spatiality. Essentially, this is a causal conception, and modern physics recognizes no action at a distance. All of this, however, rests more on empirical than on logical foundations. Furthermore, the contemporary view can only be articulated in the terms of differential equations, rendering it incomprehensible to the philosophers of antiquity.

Accordingly, it appears that the logical development of the atomists found its expression in Newton’s theory of absolute space, which also encounters difficulties in ascribing reality to non-being. There are no logical objections to this theory. The main objection lies in the assertion that absolute space is absolutely unknowable and, therefore, cannot serve as a necessary hypothesis in empirical science. A more practical objection is that physics can manage without absolute space. Yet the world of the atomists remains logically possible, and it is closer to the actual world than the worlds envisioned by any other philosophers of antiquity.

Democritus elaborated his theories in considerable detail, and some of his developments are particularly interesting. He posited that each atom is impenetrable and indivisible because it contains no void. When a knife is applied to slice an apple, it must encounter empty spaces through which it can penetrate; if the apple did not contain void, it would be utterly solid and therefore physically indivisible. Each atom is internally unchanging and represents, in fact, the Parmenidean One. The sole activity of atoms is to move and collide with one another. Occasionally, they form compounds when they happen to possess shapes capable of interlocking. There exist various types of forms; fire and the soul, for instance, consist of tiny spherical atoms. In colliding, atoms generate vortices that give rise to bodies, and ultimately to worlds.

There are numerous worlds; some grow, others decline, some may lack both sun and moon, while others possess several suns and moons. Each world has a beginning and an end. A world may be destroyed in a collision with a larger world. This cosmology can be summarized in the words of Shelley:

Worlds upon worlds roll ever, From creation to decay, Like bubbles on the surface of a river, They sparkle, burst, and fade away.

Life emerged from primordial slime. In the living body, there is a certain amount of fire present throughout, but most prominently in the brain or chest. (Authorities differ on this matter.) Thought is a kind of movement and is thus capable of eliciting movement everywhere. Perception and thinking are physical processes. Perception occurs in two forms: one sensory, the other rational. Perceptions of the latter kind depend solely on the perceived objects, whereas perceptions of the former depend also on our senses, and thus can be misleading. Like Locke, Democritus asserted that qualities such as warmth, taste, and color do not intrinsically belong to objects themselves but owe their existence to our organs of sense, whereas qualities such as weight, density, and solidity are genuinely inherent to the objects.

Democritus was a resolute materialist; as we have seen, for him, the soul consists of atoms, and thinking is a physical process. The universe lacks purpose; it consists solely of atoms governed by mechanical laws. He did not believe in the prevalent religion of his time and opposed Anaxagoras’ nous. In ethics, he regarded cheerfulness as the aim of life, with moderation and education as the best means to achieve it. He condemned all frenzy and passion; he also disapproved of sexual life, as he claimed it leads to the predominance of pleasure over consciousness. He valued friendship but spoke poorly of women. He did not wish to have children, believing that the cares of raising them hinder philosophical contemplation. In all of this, he resembled Jeremy Bentham; equally, he cherished what the Greeks termed democracy.

Democritus—at least in my opinion—is the last Greek philosopher who was free from the well-known flaw that harmed all later ancient and medieval thought. All the philosophers we have examined thus far were engulfed in an impartial quest to understand the world. They envisioned this task as simpler than it truly was; yet without such optimism, they would have lacked the courage to embark on it.

Their worldview was predominantly a genuinely scientific perspective, whenever it did not merely reflect the prejudices of their time. But this perspective was not only scientific; it was vivid and expressive, replete with delight in bold enterprise. They were interested in everything: meteors and eclipses, fish and vortices, religion and morality; their keen intellect was coupled with childlike curiosity.

From this point onward, signs of decline first emerge, despite the unparalleled achievements that preceded them, leading to a gradual disintegration. In philosophy, even in the best philosophy after Democritus, there is a detrimental overemphasis on humanity at the expense of the quest for knowledge of the universe. Initially, alongside the sophists, skepticism arises, directing attention to the study of how we know rather than striving to acquire new knowledge. Subsequently, with Socrates, the focus shifts to ethics; with Plato, there begins the denial of the sensory world in favor of a self-creating realm of pure thought; with Aristotle, the belief in purpose emerges as a fundamental concept of science. Despite the genius of Plato and Aristotle, their thought contained flaws that proved infinitely detrimental. After them, there commenced a decline in energy and a gradual resurgence of vulgar prejudices. A new worldview arose, partly as a result of the triumph of Catholic orthodoxy; yet until the Renaissance, philosophy could not regain the energy and independence characteristic of the predecessors of Socrates.