Logical Investigations

Husserl's breakthrough work, published in two volumes in 1900 and 1901, and the book that launched phenomenology. Volume One, the Prolegomena to Pure Logic, attacks psychologism: the view that the laws of logic are laws about how human minds happen to think. Husserl argues that logical truths are ideal and hold whether or not anyone thinks them. Volume Two contains six investigations into how such ideal meanings are given in experience. The First treats expression and meaning; the Second, abstraction and universals; the Third, wholes and parts; the Fourth, a pure grammar of meanings. The Fifth develops the theory of intentionality, the directedness of consciousness towards objects, and analyses acts and their contents. The Sixth explains knowledge as the fulfilment of an empty meaning-intention by intuition, introduces categorial intuition, and treats truth as evidence. The call to go back 'to the things themselves' comes from the introduction to Volume Two.

It is where phenomenology begins, and its case against psychologism and its account of intentionality still matter to logic, philosophy of mind and anyone reading Heidegger, Stein or Merleau-Ponty.