“I am sitting with a philosopher in the garden; he says again and again 'I know that that’s a tree', pointing to a tree that is near us. Someone else arrives and hears this, and I tell him: 'This fellow isn’t insane. We are only doing philosophy.”

Austro-British philosopher

Ludwig Josef Johann Wittgenstein was an Austro-British philosopher associated with logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. He is known for work that shaped twentieth-century philosophical debate, especially in these fields. His writing centers on how language works, how thought is expressed, and the foundations of reasoning and meaning.