Eucleides of Megara

Euclid (or Eucleides) of Megara, a Greek Socratic
philosopher who lived around 400 BC, founded the Megarian
school of philosophy. Editors and translators in the Middle
Ages often confused him with Euclid of Alexandria when
discussing the latter's Elements. Most modern translations
of Plato's Theaetetus render his name "Euclides."
The Megaric sect was instituted by Euclides of Megara,
and took its name from the place which gave birth to its
founder. From its disputatious character, it also received
the appellation of Eristic ( Eristiki, from erizein, " to
contend") ; and it was likewise termed the Dialectic, not
because it gave rise to dialectics or logical debates, which
had before this time exercised the ingenuity of
philosophers, particularly in the Eleatic school, but
because the discourses and writings of this class of
philosophers commonly took the form of a dialogue.
Euclides was a native of Megara, the capital of the
district of Megaris. According to some less probable
accounts, he was born at Gela, in Sicily. He was one of the
chief disciples of Socrates, but, before becoming such, he
had studied the doctrines, and especially the dialectics of
the Eleatics. Socrates on one occasion reproved him for his
fondness for subtle and captious disputes. On the death of
Socrates, Euclides, with most of the other pupils of that
philosopher, took refuge in Megara, and there established a
school which distinguished itself by the cultivation of
dialectics. The doctrines of the Eleatics formed the basis
of his philosophical system. With these he blended the
ethical and dialectical principles of Socrates. The Eleatic
dogma, that there is one universal, unchangeable existence,
he viewed in a moral aspect, calling this one existence the
Good, but giving it also other names (as Reason,
Intelligence, etc.), perhaps for the purpose of explaining
how the real, though one, appeared to be many. He rejected
demonstration, attacking not so much the premises assumed as
the conclusions drawn, and also reasoning from analogy. He
is said to have been a man of a somewhat indolent and
procrastinating disposition. Euclides was the author of six
dialogues, no one of which, however, has come down to us. He
has frequently been erroneously confounded with the
mathematician of the same name.
Euclides introduced new subtleties into the art of
disputation, several of which, though often mentioned as
examples of great ingenuity, deserve only to be remembered
as proofs of egregious trifling. Of these sophistical modes
of reasoning, called by Aristotle Eristic syllogisms, a few
examples may suffice.
1. The Lying sophism : If, when you speak the truth, you
say, you lie, you lie : but you say you lie, when you speak
the truth ; therefore, in speaking the truth, you lie.
2. The Occult : Do you know your father ? Yes. Do you know
this man who is veiled ? No. Then you do not know your
father, for it is your father who is veiled.
3. The Sorties : Is one grain a heap ? No. Two grains ? No.
Three grains ? No. Go on, adding one by one ; and, if one
grain be not a heap, it will be impossible to say what
number of grains make a heap.
In such high repute were these silly inventions for
perplexing plain truth, that Chrysippus wrote six books upon
the first of these sophisms ; and Philetas, a Coan, died of
consumption, which he had contracted by the close study that
he had bestowed upon it.
Euclides' philosophy was a synthesis of Eleatic and
Socratic ideas. He identified the Eleatic idea of "The One"
with the Socratic "Form of the Good," which he called
"Reason," "God," "Mind," "Wisdom," etc. This was the true
essence of being, and was eternal and unchangeable. As he
said, "The Good is One, but we can call it by several names,
sometimes as wisdom, sometimes as God, sometimes as Reason,"
and he declared, "the opposite of Good does not exists."
While these doctrines may appear to contradict empirical
reality, he argued that, since non-being cannot exist
without becoming a species of being (i.e., no longer
"non-being"), and since the essence of Being is the Good,
the opposite of the Good cannot exist. His doctrinal heirs,
the Stoic logicians, inaugurated the most important school
of logic in antiquity other than Aristotle's peripatetics.
Euclides had three important pupils: Eubulides of
Miletus, Ichtyas – the second leader of the Megarian school
– and Thrasymachus of Corinth. This last one was the master
of Stilpo, who was the master of Zeno of Citium, the founder
of the stoic school.