Early classical scholars such as John Burnet made the Ionian, Pre-Socratic philosophers out to be wholly secular and naturalistic far more than they actually were. The Pre-Socratics certainly “laid the foundations for the decline of the old mythological conception of the gods and of traditional religion,” according to James Thrower in Western Atheism: A Short History (Prometheus Books, 2000). They also paved the way for a naturalistic interpretation of the world, but they were not atheists.
Plato, in his last work The Laws, criticizes three positions: first, atheism; second, the view that though the gods exist they are uninterested in us; and, third, “though they are interested in us, they can be bought off with sacrifices and other bribes.” According to David Sedley:
[T]he Laws, was written around 350 BCE, but the dramatic date of the protracted conversation in which it consists is indeterminate, and could as well represent the late fifth century (as do most of Plato’s other dialogues) as the mid fourth. What the Laws makes clear is that, at this dramatic date, whatever it might be, atheism is rife in Athens. Plato’s main speaker, the Athenian stranger, remarks that, where he comes from, atheism is fashionable among the young, who rely on the authority of various written texts, some of them prose works, some verse.
But we do not have any list of names for these atheists. We do know of an agnostic, the Sophist Protagoras, who wrote in his work On the Gods: “As regards gods, I am unable to know either that they exist or that they do not, or what form they have. For there are obstacles to knowing: the obscurity of the matter, and the shortness of human life.” Protagoras’s words suggest that there was a cultural context in which positive atheism was a possibility and acceptable.
Perhaps the first name on any canonical register of atheists would have to be Critias, an uncle of Plato. According to David Sedley in The Oxford Handbook of Atheism (2013), he was said to be “the author of a scandalous dramatic passage, known today as the Sisyphus fragment, in which the speaker alleges that the gods were invented by politicians or lawmakers. Placed in the mouth of the mythical villain Sisyphus, the theory runs as follows.”
Because the earliest laws proved ineffective against those who had found ways of committing crimes unobserved, someone had the brainwave of inventing superhuman supervisors who could see everything we do and even read our thoughts:
“Hence he introduced the divine, saying that there is deity endowed with immortal life, who with his mind hears, sees, understands and takes account of these things, and who bears a divine nature—one who is going to hear everything said among mortals, and be able to see everything they do. If you plan some misdeed silently, this will not escape the gods’ notice, for there is <exceptional> power of understanding in them.” (as quoted by Sextus Empiricus, Against the professors 9.54)
Sisyphus thought it was a stroke of genius to locate the “gods” in the sky because the sky is the source of two of the greatest benefits to mankind, sun and rain, and, of course, two of the greatest terrors, such as thunder and lightning. If pleased with us, the gods could be our benefactors, but they could deliver the greatest threats if displeased with us.
However, it is not at all certain if Critias was really the author of the above passage. Some sources attribute it to Euripides. Because not recognizing the gods was a punishable offense, it is hardly surprising the real author wished to remain anonymous.
As Sedley argues, the atheists criticized in Plato’s Laws really did exist; they had evidently worked out a well-developed position that Plato took seriously and of which he gave ample details. This means there really was a coherent movement of positive atheism in late fifth- and/or early fourth-century Athens, making it “the earliest comprehensive defence of positive atheism.”
Here is an excerpt from Plato’s Laws:
Athenian: The facts show—so they [the atheists] claim—that the greatest and finest things in the world are the products of nature and chance, the creations of art being comparatively trivial. The works of nature, they say, are grand and primary, and constitute a ready-made source for all the minor works constructed and fashioned by art—artefact as they’re generally called. …
I’ll put it more precisely. They maintain that fire, water, earth and air owe their existence to nature and chance, and in no case to art, and that it is by means of these entirely inanimate substances that the secondary physical bodies—the earth, sun, moon and stars—have been produced. These substances moved at random, each impelled by virtue of its own inherent properties, which depended on various suitable amalgamations of hot and cold, dry and wet, soft and hard, and all other haphazard combinations that inevitably resulted when the opposites were mixed. This is the process to which all the heavens and everything that is in them owe their birth, and the consequent establishment of the four seasons led to the appearance of all plants and living creatures. The cause of all this, they say, was neither intelligent planning, nor a deity, not art, but—as we’ve explained—nature and chance. Art, the brain-child of these living creatures, arose later, the mortal child of moral beings; it has produced, at a late stage, various amusing trifles that are hardly real at all—mere insubstantial images of the same order as the arts themselves (I mean for instance the productions of the arts of painting and music, and all their ancillary skills). But if there are in fact some techniques that produce worth-while results, they are those that co-operate with nature, like medicine and farming and physical training. This school of thought maintains that government, in particular, has very little to do with nature, and is largely a matter of art; similarly legislation is never a natural process but is based on technique, and its enactments are quite artificial. …
My dear fellow, the first thing these people say about the gods is that they are artificial concepts corresponding to nothing in nature; they are legal fictions, which moreover vary very widely according to the different conventions people agree on when they produce a legal code.
This kind of atheism was presented by Plato as undermining morality, because it called for an abandonment of “conventional” or “legal” values. As Sedley concludes, “Greek religion had evolved in partnership with law, and we should not be surprised if liberation from the former was widely perceived as bringing with it a corresponding liberation from the latter.”
There is some evidence that “philosophers belonging to or influenced by the Cynic movement are reported to have expressed suitably provocative doubts about recognizing and/or cultivating the gods.” One such philosopher was Diogenes the Cynic, who remarked that he did not know whether the gods exist, “only that it is expedient that they should.” [Emphasis in original.]
During the Hellenistic age—the period between the collapse of Alexander’s empire in 323 BCE and the start of the Roman Empire as signaled by the Battle of Actium in 31 BCE—the Epicurean school emerged with its revised atomism. In a famous letter to Menoeceus, Epicurus (341–270 BCE) asserts “that there are gods, with an instruction to us to conceive those gods in a way which will ‘protect’ them.” Some have taken this to mean that Epicurus was indeed “referring, in realist mode, to biologically immortal beings.” But as Sedley points out, “the language chosen at least licenses an idealist alternative, that our gods are a projection of our own thought, whose invulnerability it falls to us to ensure.” According to Sedley’s own idealist interpretation of Epicurus’s philosophy, the indestructible beings envisaged by the realist interpretation
could not actually exist in an Epicurean universe, where all compounds are emphatically said to be subject to eventual dissolution; nor could apparently living dream figures, elsewhere dismissed by Epicurean physics as a source of illusion (Lucretius 4.722–822), possibly provide telepathic knowledge of the gods as far-distant biologically immortal beings. Rather, Epicurus’ real meaning is taken to be that we intuitively construct the gods as projections of our own moral ideal, visualizing them especially in our dreams, in which we ourselves compose them out of the constantly available images, just as we do all other dream pictures (Lucretius 4. 962–1036). The gods do exist, then, but as our intuitive thought-objects. They play a vital role in ethics by representing our moral ideal. The underlying conception is of entirely tranquil beings, altogether unaffected by the fear of death which so plagues human lives, and uninterested in building and governing worlds, since such activities would detract from their sublime peace of minds, much as political involvement detracts from human happiness.
The gods are idealizations of the Epicurean way of life. They are idealized versions of our own human lives. The popular characterizations of the gods as warlike are projections of human thought. Epicurus denies all divine intervention in the running of the world, thus liberating humans from the fear of divine wrath.
Euhemerus (late fourth century BCE) exercised much influence on Hellenistic and Roman philosophy; according to Sedley, the word euhemerism is “a regular term for the policy of rationalizing myth to the point where it no longer contains any divine element.” He himself described the human origin of the traditional gods Ouranos, Cronos, and Zeus.
I can only very briefly sketch some other aspects of skepticism and atheism in antiquity. The most significant development in the post-Aristotelian period is the rise of the Sceptics, whose origins go back to Pyrrho of Elis, a contemporary of Aristotle. It seems Pyrrho believed that as nothing can be known with complete certainty, we cannot and should not deny or affirm anything. This attitude can lead only to agnosticism, especially concerning the gods. Arcesilaus introduced skeptical doctrines into the Platonic Academy. For the skeptic Carneades of Cyrene (213–129 BCE), there could be no certainty about religious belief. Carneades had argued against the existence of gods, but Cicero makes out that Carneades was not arguing against existence of gods tout court but, in fact, arguing against the Stoics and their failure to establish with any kind of certainty the existence of gods. However, Sedley does not accept Cicero’s contention; Cicero, in an apologetic vein, was merely making a concession to Roman conservatism. Sextus Empiricus has preserved many of Carneades’s arguments, nearly all of which end in “Therefore there are no gods.” Sedley thinks these arguments are aimed not necessarily at the Stoics alone but “are aimed against a broad coalition of theists, without discrimination among them, and draw their premises from a similarly broad range of respectable sources. In response to this coalition, they aim specifically to make a case for the non-existence of the gods.”
The Stoics had pointed to the putative ubiquity of the belief in gods. Carneades, on the other hand, argued that the universality of theism was doubtful but that, even if this universality is granted, all it proves is the sociological or anthropological fact that humans believe in the existence of gods. Further argument is needed to establish their existence. Also, one cannot decide matters of truth by counting hands in a simple vote.
Philosophical and popular theologies had failed to determine where the boundary of the divine is located. Sedley explains:
Likewise the divinization of major cosmic components, such as the sea’s identification with Poseidon, left the status of smaller bodies of water in doubt: rivers were generally divinized too, but in that case why exclude streams, and even seasonal torrents? Carneades’ sorites [or “little-by-little”] arguments thus typically took the form, “If A (e.g. Zeus) is a god, B is god, C is a god; … if F is a god, G (e.g. torrent) is a god; but G is not a god; therefore A is not a god; but if there were gods. A would be a god; therefore there are no gods.”
Carneades further argues that the Stoics’ concept of God is not only false but meaningless in that it is self-contradictory. But his arguments count against any conception of God. Further, we cannot ascribe to God personal attributes without limiting his nature.
The three leading figures of Roman civilization who are essentially secular or humanistic are Cicero, Lucretius, and Pliny the Elder. Cicero, being a good citizen and a statesman, stood by the established Roman religion publicly. But for all intents and purposes, he was a practical if not theoretical atheist. The upper classes in general ignored religion.
Lucretius was inspired by Epicurus but developed his own philosophy, which he expounded in his literary masterpiece, On the Nature of the Universe. It was entirely atheistic. Thrower describes this: “His attitude is that of one who is reconciled to life by the calm contemplation of law as it reigns in the universe and by the knowledge that the gods do not exist and that life ends in death. Religion, he holds, is guilty of many misdeeds … and so ought to be abolished.”
In Pliny the Elder we find pantheism, which identifies God with the universe. He wrote, “I therefore deem it a sign of human weakness to ask about the shape or form of God. Whoever God is, if any other God (than the Universe) exists at all, and in whatever part of the world he is, he is all preception, all sight, all hearing, all soul, all reason, all self.”
Early classical scholars such as John Burnet made the Ionian, Pre-Socratic philosophers out to be wholly secular and naturalistic far more than they actually were. The Pre-Socratics certainly “laid the foundations for the decline of the old mythological conception of the gods and of traditional religion,” according to James Thrower in Western Atheism: A Short …