6 ideas
On All Saints' Day 1755 an earthquake, fire, and tsunami destroyed Lisbon and killed tens of thousands, many of them at worship in its churches. Voltaire uses the concrete image of women and children crushed under rubble to force the abstract doctrine to answer for a specific event. Measured against real, particular bodies, 'whatever is, is right' stops sounding like wisdom and starts sounding obscene.
Telling victims that their agony serves a greater harmony adds contempt to their pain, because it asks them to approve of their own destruction. Voltaire argues that consolation built on systemic justification is cruelty dressed as philosophy. The honest response to catastrophe is to name it as evil, not to explain it away.
Voltaire asks whether Lisbon, which was destroyed, was more sinful than London or Paris, where people went on enjoying themselves. Disasters do not distribute suffering according to guilt, so any theodicy that treats catastrophe as punishment is refuted by the pattern of who actually dies. Looking at the random targeting of harm dissolves the idea that it is retributive.
The optimist says private misfortunes combine to make up the general good. Voltaire counters that summing individual miseries yields only a larger misery, not happiness. A system cannot be called good for everyone when the people inside it are crushed.
Leibniz and Pope treat each evil as a necessary link in a great chain of beings and events, so that removing it would collapse the whole. Voltaire objects that an omnipotent, free God cannot be bound by any such chain of necessity. Defending God through necessity ends up denying God's freedom, and so undermines the doctrine it was meant to support.
Voltaire rejects both despair and false certainty, and admits he cannot solve the problem of evil. He keeps only a modest hope that things may be well someday, and denies they are well today. The stance holds three things together: say what is known, confess what is not, and refuse to rename suffering as good.