Stefan Buijsman obtained his PhD in the philosophy of mathematics at 20, and has since then focused on the interplay between philosophy and other disciplines. His early work looked at the link between philosophy of mathematics and cognitive science research on how people learn mathematics, and resulted in two popular science books, one of which (Pluses and Minuses) was published in over 20 countries. Now he works at Delft on the connection between philosophy and artificial intelligence, where he co-founded the TU Delft Digital Ethics Centre and runs several labs focussed on translating ethical values for AI into concrete design requirements.