Multiple Explanations

Epicurus is not primarily interested in natural science for its own sake — he is interested in it as a tool for removing anxiety. The investigation of celestial and terrestrial phenomena is valuable because it dissolves the superstitious interpretation of natural events as divine messages or punishments. Once one understands that thunder has natural causes, one no longer fears it as a sign of Jupiter's anger. The specific natural cause — whether thunder results from friction, collision, or the compression of clouds — is far less important than the general understanding that a natural cause of some kind exists. For this therapeutic purpose, multiple explanations are not a failure of science but an asset.

Epicurus's methodological pluralism is also a form of epistemic humility. The phenomena of the distant sky and the depths of the earth are not accessible to direct inspection; our evidence for what causes them is always indirect and underdetermining. To insist on a single explanation in these circumstances is to go beyond what the evidence warrants — to treat a hypothesis as if it were an observation. This is the kind of intellectual overreach that generates the false beliefs and vain dogmas that Epicurus regards as a major source of human misery. Better to maintain multiple hypotheses, all consistent with experience, than to commit to one and be bound by a claim that may be false.

Multiple explanations are not a counsel of permanent agnosticism. Where experience and observation can settle the question — where the evidence discriminates among the candidates — Epicurus is happy to do so. The rule of multiple explanations applies precisely in cases where it does not. This creates a productive scientific practice: gather as much observational evidence as possible; where the evidence is decisive, draw conclusions; where it is not, hold the alternatives open. The Letter to Pythocles applies this method systematically to dozens of phenomena — the phases of the moon, the nature of comets, the causes of earthquakes — demonstrating its operation in detail.

The method of multiple explanations (Greek: pleonachos tropos) appears throughout the Letter to Pythocles and is also applied in the Letter to Herodotus. It has attracted considerable scholarly attention as an early statement of underdetermination in the philosophy of science. David Sedley's Lucretius and the Transformation of Greek Wisdom (1998) discusses its significance in context.