3. Plato
The dialogues of Plato (c.429–347 BCE) reveal a broad familiarity with many species of animals, although Plato’s interest in animals is more that of a metaphysician than of a biologist. Animals figure in his works rather frequently as metaphors and as images, and animality is quite often contrasted with humanity in Plato, to the disadvantage of animalkind: humans who do not live up to their potential as rational beings are likened to beasts that wallow in their lowliness, while those who remain uneducated are said to resemble the wildest of beasts (Laws 766a). Similarly, democratic government is said by Plato to be like a pack of animals that are impossible to control (Republic 563c). In common with a number of other ancient writers, he considered some kinds of animals, including bees and ants, to be positive models for human conduct, while others, such as wolves and lions, were emblematic of savagery and not to be emulated in human behavior.
Despite his fondness for metaphorical constructions of animality, it would be erroneous to claim that Plato had no scientific interest in animals. Although the criteria by which he distinguishes them are at times fanciful and unilluminating, he seems to have been interested in establishing a system of classification of animal species. He distinguishes animals at times according to their manner of breeding or feeding, but he never attains to any consistent position on division between species. Indeed, biologists tend to feel that Plato’s playful and imaginative treatment of animals had in the final analysis a rather baneful influence on the progress of science, and he is not often accorded a place of honor in the ranks of Greek biologists.
One of the more intriguing appearances of animals in the Platonic corpus is found in the philosopher’s doctrine of metempsychosis, usually understood to mean the transmigration of souls, a belief often associated with the pre-Socratic philosopher Pythagoras (6th century BCE). The doctrine of transmigration of souls is discussed in the Phaedrus, the Republic, the Phaedo, and the Timaeus, although these discussions do not agree in all details. In the Phaedo, Plato maintains (81e–82b) that humans may assume the form of other animal species through metempsychosis, depending upon their former manner of life: those who were gluttons and drunkards may become asses, while those who were unjust and tyrannical may pass into wolves or hawks. In contrast, those who displayed what he terms practical political virtues such as temperance and justice pass into gentle, “political” species such as ants or bees. In the Republic, however, a greater range of possibilities is explored (620d): some humans are said to choose a reincarnation that resembles their former mode of life, as Orpheus elected to be reborn as a swan and Aias as a lion. In this dialogue, animals are also envisioned as being capable of choosing to be reborn as human beings, as is said to be the case with swans. Similarly, he argues in the Timaeus that those individuals who did not allow their spiritual element to predominate entirely in their lifetimes will return as animals, and that the more irrationally an individual behaved in one life, the lowlier the animal species into which he will pass in his next incarnation (42c). The apparent lack of agreement in Plato’s accounts has proved troubling to scholars since antiquity, and he allows Socrates to state (Phaedo 114d) that no reasonable person can take what he has described as incontrovertible fact, but it is remarkable how frequently the topic of transmigration of souls is encountered in the Platonic corpus. It also remains unclear what Plato believed happens to human reason when a person passes into an animal and, conversely, when an animal passes into a human. In the Phaedrus (249b), he sidesteps this problem altogether by declaring that only what had previously been a human soul can pass back into a human. In both the Phaedrus and the Republic, Plato discusses the punishments that some souls may expect in the afterlife, but this possibility is not broached in either the Phaedo or the Timaeus. The Phaedo also does not mention the possibility of animals passing into humans in their incarnations.
It is likewise difficult to assess Plato’s position on the question of rationality in animals since he seems to waver in his views. While he frequently laments the fact that humans do not always make the effort to live completely rational lives and thereby to reach their potential, he generally considers animals to have intellectual powers far inferior to those of human beings. In the passages translated below, he seems to deny rationality to animals, but in the Laws (961d) he is willing to allow them a portion of intellect (nous).