( John Tzetze ̄s, Chil. 7.647). Distances along coast-lines are given in stades (with the
exception of north-eastern Europe). The compendium Hupotupo ̄sis geo ̄graphias en epitome ̄
(E ), however, occasionally attributed to Pro ̄tagoras, belonged most
probably to the circle of the 9th c. patriarch Pho ̄tios of Constantinople.
RE 18.3 (1949) 1160–1161, K. Ziegler; RE 23.1 (1957) 921–923 (#5), F. Gisinger; NP 10.458,
H.A. Gärtner.
Andreas Kuelzer
Pro ̄tagoras of Abde ̄ra (ca 460 – 420 BCE)
The oldest and perhaps most important of the 5th c. sophists whose educational activities
and intellectual interests belong more to the social sciences than the natural sciences. But
one central doctrine of Pro ̄tagoras, that “a human being is measure of all things,” has
important consequences for all kinds of inquiry. We have only a single sentence of Pro ̄tagoras’
own words on this topic. But as explained by both P (Tht. 152a–c) and S
E (PH 1.216–219), the doctrine entails that, for any individual in a given set of
circumstances, the way things appear is the way they are. (Whether this is equivalent to
relativism, as that term is normally understood, is another question.) Pro ̄tagoras thus erases
any distinction between appearance and reality, which seems seriously to undermine the
impulse to scientific inquiry.
Plato connects Pro ̄tagoras’ “measure” doctrine with an ontology of radical flux. It is not
clear, however, whether he means to attribute this to Pro ̄tagoras himself, or suggest that
Pro ̄tagoras should have taken this as a corollary of the doctrine. What does seem to have been
connected with the measure doctrine was a suspicion of claims about matters falling outside
ordinary experience. Pro ̄tagoras’ famous expression of religious agnosticism is one of sev-
eral indications of this attitude. A Metaph. 3 (998a1–4) also reports that he took
issue with geometers about whether a line touches a circle only at a point. It looks as if his
point was that this is clearly not the case for visible straight and circular objects; the implica-
tion seems to be that any other kinds of objects, such as those of pure mathematics, are
not even worth considering. Other indications suggest he was dismissive of mathematics,
explained, presumably, in his On Mathematics.
ECP 455 – 458, P. Woodruff.
Richard Bett
Pro ̄tagoras of Nikaia (100 BCE – 350 CE)
Authored a lost astrological work entitled Sunago ̄gai, part of which H
T paraphrases for doctrines relating journeys of individuals to planetary motions
(3.30 and 3.47). The same work contained material on astrological medicine, for which it is
cited, along with similar texts attributed to H and P, in an anonymous
iatromathematical chapter in an 11th c. Byzantine astrological codex. The character of
the doctrines indicates a date no earlier than the 1st c. BCE. D L (9.56)
refers to an astrologos Pro ̄tagoras who lived about 200 BCE, probably distinct from our
Pro ̄tagoras, and probably an astronomer rather than an astrologer.
Pingree (1978) 2.438–439.
Alexander Jones
PRO ̄TAGORAS OF NIKAIA