Lisbon Earthquake of 1755: How a Disaster Reshaped Philosophy and Science

On November 1, 1755, at 9:40 am, Lisbon faced a catastrophic event comprising an earthquake, tsunami, and subsequent fires, resulting in the deaths of approximately 40,000 to 50,000 individuals and extensive destruction throughout the city. The earthquake, registering between 7.7 and 9.0 in magnitude, was triggered by the Azores-Gibraltar Transform Fault. On All Saints' Day, candles lit in cathedrals sparked fires that raged for almost a week. Witnesses along the Tagus riverbank observed the water recede before a tsunami hit 40 minutes later. Voltaire responded to this tragedy in his works, critiquing optimistic philosophy. Sebastião José de Carvalho e Melo spearheaded a secular relief initiative, while Immanuel Kant suggested a now-debunked theory regarding subterranean gases. This calamity influenced European thought, steering it towards secularism and scientific inquiry, thereby laying the groundwork for the Enlightenment.