For Leibniz, contingency means an infinity of possible alternative selves surrounds each real one

Evidence

Leibniz held that extension cannot be an attribute of a substance. His reason was that extension involves plurality, and can therefore only belong to an aggregate of substances; each single substance must be unextended. He believed, consequently, in an infinite number of substances, which he called ‘monads’. Each of these would have some of the properties of a physical point, but only when viewed abstractly; in fact, each monad is a soul. — Bertrand Russell, History of Western Philosophy, 2128 (#expands, via linked claim)

Categorization

• XREF: connects to: Leibniz defined an infinite number of unextended soul substances called monads. — Bertrand Russell, History of Western Philosophy, 2128; Leibnizian possibility is epistemic, relative only to our ignorance

Broader Connections

• Leibnizian possibility is epistemic, relative only to our ignorance #contradicts (0.82)
• Leibniz defined an infinite number of unextended soul substances called monads. #expands (0.80) — Bertrand Russell, History of Western Philosophy, 2128