phrase
Latin
I Think, Therefore I Am
lit. โcogito, ergo sumโ
Descartes' bedrock proof that he exists, because he's thinking.
Origin
Descartes set out to doubt everything that could be doubted. The one thing he couldn't doubt: that there was someone doing the doubting. The cogito became the starting point for modern philosophy.
Modern usage
Quoted in everything from AI debates to t-shirts. Often modified for jokes: 'I shop, therefore I am.'
Tags
existence
rationalism