Abstract

In his Pensées, Pascal introduced the very influential distinction between the subtle intelligence and the geometrical intelligence. In the first part of the present paper Pascal’s distinction is considered by looking at his famous wager argument where Pascal acts as a skeptical philosopher and at the same time as an applied mathematician. This argument employs the esprit de finesse in a way that is of fundamental significance for the epistemology of mathematics. This claim will be backed up in the second part of the paper that explores Charles Sanders Peirce’s conception of diagrammatic reasoning. Peirce’s semiotically inspired epistemology of mathematics brings to the fore the significance of the “old”position of Pascal – one has to face the fundamental problems of application.