How Posture Makes Us Human

The very notion of what in the ancient world defines the human being in contrast to all other living things is simple: upright posture. Best known of the ancient commentators is Plato, who, according to legend, is claimed to have seen the human as bipedal and featherless. To describe humans as “featherless” sounds odder to modern ears than does the functional association of bipedalism and intelligence, but Plato sees the absence of bodily covering as a move away from the base toward the human, for he is quite aware that the other bipedal animal is the bird. Greek thought gives the bird a middle role between the human and the gods, since birds are connected to the gods through their use in divination. Responding to Plato’s contorted definition of man, Diogenes of Sinope, known as the Cynic, notoriously plucked a (bipedal) chicken and took it to Plato’s Academy, declaring, “Here is Plato’s man.”¹

Although bipedalism seems to us an obvious way of seeing human beings, it was Plato who used upright posture to move the rational mind as far from the center of the appetite and the organ of generation as possible: The head, for Plato, is the “acropolis” of the body, its highest point both literally and metaphorically. The state is to the upright body as the body is to the city­state. Plato’s upright body at its best must also possess wisdom and nobility, agathos kai sophos (ἀγαθὸς καὶ σοφὸς), which he abstracts in the Meno from the older Greek notion of kalos kagathos (καλός καγαθός), beauty and goodness.² This older concept describes military posture, in the sense both of the soldier’s body and of his loyalty to the state.

The tension here between absolute definitions of posture, such as the Platonic one, and their antithesis, Diogenes’ chicken, sets the pattern for all subsequent debates about posture, even though over time the latter seems to have won the day. Bertrand Russell dissected the implications of this notion for symbolic logic in the early 20th century when he noted, “ ‘Socrates is a featherless biped’ is different from ‘Socrates is human’,” in that the latter set of classifications is all-encompassing; the former clearly not. By the 20th century only such ironic evocations are possible. Russell implies that no one in his world would even imagine this as a possible definition of the human.