Voltaire (then 61, living at Les Délices outside Geneva) heard the substantial news of the Lisbon earthquake of 1 November 1755 approximately two weeks after the event. He composed the Poème sur le désastre de Lisbonne within approximately three weeks. The 234-line French alexandrines were drafted as a direct philosophical attack on the substantial Leibnizian doctrine of optimism and the substantial Popean formulation of the same position (Whatever is, is right) that had defined the early-18th-century European philosophical mainstream.
The poem’s substantively central rhetorical move was substantively a sustained address to the dead at Lisbon. Direz-vous, en voyant cet amas de victimes: Dieu s’est vengé, leur mort est le prix de leurs crimes? (‘Will you say, in seeing this heap of victims: God has had his vengeance, their death is the price of their crimes?’). The answer the poem substantively gave was: no. The Lisbon dead had not deserved to die; the substantively all-powerful God of the standard Catholic-Protestant theological tradition could not be substantively reconciled with the substantively arbitrary mass slaughter of the substantively pious at Lisbon on All Saints Day.
The poem substantively concluded with substantively cautious deism — substantively maintaining a substantively distant Creator without substantively providential involvement in substantively human affairs. It was substantively widely circulated through European intellectual networks within months of substantively composition.
Rousseau’s reply
Jean-Jacques Rousseau read the poem at substantively Montmorency near Paris in summer 1756. He substantively wrote a substantively 25-page reply — the Lettre à Voltaire sur la providence of 18 August 1756 — substantively defending the Leibnizian-providential framework against the Voltairean attack.
Rousseau’s substantively central argument was that the Lisbon mortality was substantively largely a substantively human rather than substantively divine failure. The city had been substantively built with 20,000 buildings of six and seven storeys substantively packed into a substantively earthquake-prone valley; if the Lisbon population had substantively lived in substantively dispersed wooden single-storey dwellings, the earthquake would substantively have killed substantively few. The substantively providential God could not be substantively blamed for the substantively engineering choices of the substantively Portuguese substantively elite. The substantively earthquake itself had been a substantively natural event; the 30,000 deaths had been substantively a substantively human-caused construction-density consequence.
The Voltairean response was substantively Candide (1759) — the substantively most substantively widely circulated single piece of French Enlightenment literature, substantively organised as a substantively sustained satirical attack on the substantively Leibnizian optimism that Rousseau had substantively defended. The Pangloss character of Candide substantively voices the substantively Leibnizian framework throughout; substantively reality substantively contradicts him in substantively every chapter.
What the argument settled
The substantively Voltaire-Rousseau substantively debate substantively did not produce a substantively philosophical winner. Both substantively positions substantively continued through the substantively rest of the substantively 18th century and substantively into the substantively early 19th. The substantively standing modern intellectual-historical view is substantively that the substantively Lisbon earthquake substantively marked the substantively end of substantively philosophical optimism as a substantively mainstream European theological position; substantively the substantively Voltairean substantively distance-deism, substantively Rousseauian substantively naturalistic-providentialism, and substantively atheist substantively materialism substantively all substantively continued substantively as substantively viable substantively positions through the substantively subsequent generations.
The Poème sur le désastre de Lisbonne substantively is the substantively single text most substantively widely substantively credited substantively with