Sigmund Freud had mixed feelings about philosophy – he thought that philosophers and people experiencing psychosis had a lot in common. So how has contemporary philosophy come to owe such a huge debt to the father of psychoanalysis? Heidegger, Ricoeur, Derrida, Zizek – all employ a “hermeneutics of suspicion” that looks for meanings below the surface of manifest phenomena, and all employ techniques that draw heavily on Freudian insights.