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Dictionary of the History of Ideas

Studies of Selected Pivotal Ideas

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The Epicureans were followers of Epicurus, a Greek
philosopher who lived from 341 to 270 B.C. The most
important of them to us is Lucretius, a Roman poet


of the first century B.C., whose De rerum natura is the
fullest account of Epicurus' philosophy that we possess.
Nearly all Epicurus' own writings are lost. One prob-
lem raised by them is that of free will, the problem
whether a man's actions are entirely determined by
his inherited characteristics, his past experience, and
his present circumstances, or whether sometimes at
least he has a free choice between alternative courses
of action. The word “will” must not be pressed here:
indeed the Greeks had no word exactly equivalent to
it, but the problem is one that they were able to
understand and formulate without difficulty. It is inde-
pendent of any particular psychological terminology.

Many modern philosophers have written about this
problem. Some say that freedom is an illusion, and that
all our actions are determined; others deny this, and
try to show how determinism can be avoided, while
a third group argues that determinism and freedom
are in fact compatible, and only seem to be opposed.
But they are all agreed that there at least appears to
be a problem, and the intelligent layman also sees the
difficulty, for it arises from assumptions that he takes
for granted. The earlier Greek philosophers, however,
do not seem to have been aware of any such problem,
although they were familiar with the elements of it.
Plato, for instance, in the Republic (II-III, esp. 416;
IV 429-30; V 458-61; VI 490-92), discusses a program
for breeding human beings which implies that he be-
lieved in the influence of heredity, and a program for
educating them which implies that he believed in the
influence of training, but he does not generalize from
these two points and conclude that a man's actions are
entirely the result of these and other external factors.
Both Plato, in the Laws, and Aristotle, in the Nico-
machean Ethics,
discuss problems of punishment and
voluntary action from a legalistic standpoint, and in
their discussion they touch on a number of arguments
that, if followed up, might lead to thoroughgoing
determinism, but such arguments are not taken very
seriously. This is not surprising. Both men were con-
cerned with limited problems bearing on practical
issues—good government and law—and did not go
beyond them. One very good reason for this, mentioned
by Aristotle, is that thoroughgoing determinism de-
stroys the natural basis for a distinction between vol-
untary and involuntary actions: all actions become
involuntary because a man cannot help but do them.
But for the purposes of the law it is vital to be able
to regard some actions as voluntary, for it is only these
that can justifiably be punished. For Aristotle, this
argument seemed to be final.

Epicurus was different. Like Aristotle, he was inter-
ested in the applicability of punishment, advice, and
similar concepts, but he was not content to accept
Aristotle's approach. One reason was that he had taken
over from the great atomist philosopher, Democritus
(ca. 460-390 B.C.), an account of the nature of the
universe which seemed to involve determinism and at
the same time simplified, or perhaps oversimplified, the
issues. According to Democritus, the universe consisted
solely of atoms of solid matter moving through empty
space. Every large-scale object, including gods and
men, was made up entirely of such atoms and the
spaces between them. Being of different shapes, atoms
could combine with each other in many ways, and the
differences between one thing and another could be
accounted for entirely in terms of such combinations.
Even the soul was material, though composed of the
finest and most easily moving atoms. All observable
changes were to be explained by changes in the atomic
microstructure, and all these were changes in the
spatial relations of atoms among themselves: atoms
could not change internally. This theory involved
determinism, because given the original shape, speed,
and direction of the atoms, or their shape, speed, and
direction at any single moment of time, all later states
of the universe would necessarily follow, including all
the states and actions of every individual man. Not
only this, but the theory also reduced psychological
causation to mechanical or physical causation, and so
simplified the issues. It was possible for earlier thinkers,
including Plato and Aristotle, to treat psychology as
an independent field, as indeed we frequently do today.
But if minds are no more than combinations of atoms,
they are bound by the laws of atomic behavior, and
if atomic behavior is fully determined, then so is psy-
chology. Hence the issues presented themselves with
peculiar sharpness.

The fact that all men's actions would thus be com-
pletely determined does not seem to have worried
Democritus, but for Epicurus it was a stumbling-block.
Indeed he says explicitly that “it would be better to
follow the myths about the gods than to be a slave
to the determinism (heimarmene, εἱμαρμένη) of the
physicists. For you can hope to appease the gods with
worship, but you cannot appease necessity” (Letter to
134). He had two main reasons for believing
in free will. The first was that he observed a kind of
spontaneity in human beings—and perhaps in some
animals—which appeared to consist in the ability to
originate actions. The second was that he believed that
praise and blame, reward and punishment, advice and
reproach, which men use freely in their relations with
one another, are out of place unless men are genuinely
free to choose one course of action rather than another.
For you cannot blame or punish a man for something
he cannot help doing.

Unfortunately we have lost nearly all of Epicurus'
writings, and those that we have tell us little about
the first point. But there are some detailed examples of


it in Lucretius, whose long poem is an account of the
system of Epicurus, and follows Epicurus very closely.

His first example of spontaneity seems, surprisingly,
to be about the behavior of horses at the start of a
race (De rerum natura II, 263-71). This raises difficul-
ties, as in some of his fragmentary works Epicurus
seems to deny that animals can have free will, and it
may be that this passage of Lucretius has come down
to us in a corrupt form. The second example is of a
man who is pushed or dragged headlong by some
external force, but is able to oppose it and stand his
ground because of something within his breast which
has the power to do so (II, 277-87).

If we are to take these examples seriously Epicurus
was not here concerned with moral decisions, but with
the ability men—and perhaps animals—have to make
a fresh start in many kinds of situations. This ability
was something that he believed one could observe. But
moral issues were also relevant, and these are indicated
in a point made by Epicurus himself in a work that
has come down to us only in fragments, his On Nature.
There he speaks of men “admonishing one another and
struggling and trying to change each others' ways as
having a causal principle in themselves, and not only
in their original constitution and in the necessity of
that which surrounds and enters them according to its
own laws” (31.27, 3-9, Arrighetti). This is the clearest
fragment we have on this point from the remains of
two books of the On Nature that were probably on
this subject. Epicurus seems to have argued several
times that all men, including strict determinists like
Democritus, tried to affect others by reproaching them
for their vices and other similar means, but this would
be pointless if in fact men had no power to change
their ways.

Although the evidence is confused in places, there
is no real ground for doubt that Epicurus believed in
free will for these reasons, and could not accept com-
plete determinism because he thought it inconsistent
with such free will. He therefore introduced some
modifications into Democritus' system. One change was
indeed independent of these issues, but has a bearing
on what follows. Democritus had held, as far as we
can tell from the evidence that we have, that the atoms
moved in all directions, upwards, downwards, or side-
ways, but Epicurus said that their natural movement
was downwards, and that all would fall at the same
speed. Atoms moving continually at the same speed
and in the same direction would however never collide
and so start off the combined motions by which larger
objects could come into being. To meet this difficulty
he added that any atom might swerve a hairsbreadth
from its straight path and so eventually collide with
another, which, rebounding, might affect a third, and
so on. In addition, the swerve (clinamen, παρέγκλισις)
would be uncaused and unpredictable, and this was
the innovation that he thought would allow for free
will. For it would break the strict chain of causation
found in Democritus' system, and in his own original
version of that system.

At this point we encounter great difficulty. There
is no ancient evidence that tells us clearly and in detail
how Epicurus thought the swerve affected human de-
cisions. Indeed the swerve is not even mentioned in
any of his tolerably complete surviving works though
it may have been in a missing part of the Letter to
But the evidence of Lucretius and some
other writers is at least enough to show that Epicurus
did introduce the swerve, and did use it to solve the
problem of free will. Or rather he tried to solve the
problem, because no satisfactory solution of this kind
is possible. The swerve provides a break in the causal
chain, but does not provide for the kind of rational
freedom that is needed. What is required is the freedom
to choose the right or prudent course even though one's
constitution and experience incline one to do what is
wrong or imprudent. But the atomic swerve will only
produce a random change in the course of events,
which need not, and probably will not, have any bear-
ing on morality. Somehow Epicurus must have pre-
sented his views in such a way that this was not too

From the fragments of the On Nature it emerges
that Epicurus recognized two causal factors in a man's
decisions, the mind's original constitution and the
pressure of external circumstances. But he insisted that
one should also distinguish a third, called, in rather
obscure technical terminology, “the generated” (to
), and that this was the seat of free-
dom. Beyond this we can only go by conjecture. Some-
how he must have linked “the generated” and the
swerve, but we do not know how. Perhaps, for the
reason suggested above, and because the matter is
almost impossibly difficult, he said very little more. It
may be that he held that when a man acted freely
there might be no more than a single swerve in a single
atom, which would break the causal chain only to the
extent of slightly changing the pattern of the atomic
dance, and so producing an action that was free but
still in character (Furley, 1967). But the difficulty of
principle remains. What we now have is a choice that
is fully determined except in a single respect, and that
single respect is a random event.

Epicurus' importance lies therefore far more in his
recognition of a problem than in the solution he gave
to it. It is probable, though the evidence is slight, that
as soon as he had formulated it it was taken up by
philosophers of many different schools, and particularly


by the Stoics. They did not accept atomism, but had
their own peculiar blend of determinism and fatalism
that seemed to rule out the possibility of free action.
From this time onwards universal causation seems to
have been taken for granted in a way far removed from
Aristotle's outlook. We even find Cicero, in his On Fate
(De fato, 44 B.C.), laughing at Epicurus for introducing
the swerve because it was uncaused, and an uncaused
event was ridiculous. Epicurus' presuppositions were
accepted, even if his solution was rejected.

It does not do, however, to see his problem solely
in the way we have done so far. It was complicated
for him by an argument of a quite different kind,
turning on a logical point. It had been much discussed
by philosophers from Aristotle downwards at the end
of the fourth century B.C., and ran something like this:
any statement is either true or false. In particular, any
statement about the future is either true or false. But
we can form disjunctions of contradictories about the
future, like “I will die tomorrow or I will not die
tomorrow.” Of these contradictories one must be true
and the other false. Therefore some statements about
the future must be true. And if, for instance, it is true
that I will die tomorrow, then it is determined that
I will die tomorrow. And, in general, the future is

Epicurus, like many others, seems to have felt that
this was a serious argument in favor of determinism
which had to be rebutted. Cicero must be mistaken
in saying that Epicurus brought in the swerve of the
atoms to solve it: rather he met it by the strictly logical
contention that in a disjunction of contradictories nei-
ther contradictory is either true or false. (Aristotle,
however, did say that statements about the future were
neither true nor false.)

However this may have been an academic answer
to what he regarded as an academic problem, and his
major interest was in the reconciling of physical deter-
minism and free will. Unfortunately our information
about the later history of his doctrine is scanty, but
it may be more than a coincidence that Saint
Augustine's account of free will in the fifth century
resembles Epicurus' in many respects, though it is set
against a theological and not a physical background.
In distinguishing between animals and men because
only the latter have free will, in saying that a man's
actions may be due solely to the “weight” of his natu-
ral impulses but that he also has a power of acting
voluntarily, and in maintaining that praise and blame
are appropriate only to voluntary action, Augustine
is making points that are all found in Epicurus' On
This does not mean that he had read Epicurus,
but suggests that the latter's ideas were by now com-
mon currency.

Epicurus urged men to use their freedom to seek
pleasure and avoid pain. But the pleasure he advocated
was a state of serene freedom from pain which could
best be attained by leading a quiet and virtuous life.
In ancient times the Epicureans were attacked on two
levels: they were vilified as gross sensualists by those
who misunderstood them, or who took as typical the
many who called themselves Epicureans without fully
understanding the doctrine, and they were criticized
by serious philosophers because they used the word
“pleasure” to cover two distinct things, freedom from
pain as well as positive pleasure, and because the
former should not be called pleasure at all; more seri-
ously, men were born for something higher than the
pursuit of pleasure (Cicero, De finibus I and II).

In Christian times the Epicureans were frowned
upon as atheists, and little read. But in the Renaissance,
through Cicero, Diogenes Laërtius, and Lucretius
himself they were rediscovered, and in humanist Italy
it was possible for a man like Lorenzo Valla (ca.
1400-57) both to write in praise of Epicurus and to
be made apostolic secretary by Pope Nicholas V. Since
then followers of Epicurus have fallen into two main
classes, those who tried to reconcile his teachings with
Christianity, and those who regarded him as the first
of a line of enlightened thinkers whose views were
incompatible with Christianity. Among the former
were Pierre Gassendi (1592-1655), priest as well as
scholar and mathematician, who combined atomism
with a belief in the immortality of the soul. Through
him atomism became known to Robert Boyle and then
to Newton, whose language in his description of atoms
shows the influence of Lucretius; Gassendi also revived
interest in Epicurus' hedonism. Again, in the nineteenth
century Walter Pater (1839-94), in his Marius the
showed a sensitivity to the highest as well
as the lowest in Epicureanism, which was not incom-
patible with at least an aesthetic interest in Christi-
anity. On the other hand the freethinking tradition of
modern Europe derives at least in part from Epicurus.
Thomas Hobbes, though he does not mention Epicurus,
must have known of him through Francis Bacon, and
Giordano Bruno (ca. 1548-1600) was burnt as a heretic
partly at least for setting out the Epicurean doctrine
of the infinity of the Universe. In seventeenth-century
France Saint-Évremond was one of several professed
Epicureans, and Fontenelle carried a similar outlook
into the middle of the eighteenth century. Even
Voltaire, too much of a fighter to be a true Epicurean,
recognized that the secret of happiness might lie in
cultivating one's own garden (Candide, 1759). The
utilitarians, too, though primarily social reformers with
keen consciences, recognized Epicurus as one of their
forerunners (J. S. Mill, Utilitarianism, Ch. I).



The major sources: Epicuro, Opere, a cura di G. Arrighetti
(Turin, 1960) has the Greek text of all Epicurus' works and
fragments, with an Italian translation; C. Diano, Epicuri
(Florence, 1946) has all the ethical works and frag-
ments; C. Bailey, Epicurus (Oxford, 1926) has a text (omit-
ting the Herculaneum fragments) with English translation
and commentary; Lucretius, De rerum natura has been
edited and translated many times. C. Bailey's edition
(Oxford, 1947) has text, English translation and commentary.
See also, G. D. Hadzsits, Lucretius and His Influence (New
York, 1963).

Modern commentary includes: C. Bailey, The Greek
Atomists and Epicurus
(Oxford, 1928), Part II, Chs. V and
VIII; C. Diano, “La psicologia d'Epicuro e la teoria delle
passioni,” Giornale Critico della Filosofia Italiana (1939),
105-45; (1940), 151-65; (1941), 5-34; (1942), 5-49, 121-50;
D. J. Furley, Two Studies in the Greek Atomists (Princeton,
1967), Study II, “Aristotle and Epicurus on Voluntary Ac-
tion”; M. Hadas, A History of Greek Literature (New York,
1950), and idem, A History of Latin Literature (New York,
1952); P. M. Huby, “The First Discovery of the Freewill
Problem,” Philosophy, 42 (1967), 353-62, and idem, “The
Epicureans, Animals, and Freewill,” Apeiron, 3 (1969),


[See also Atomism; Causation; Free Will; Stoicism.]