 In any case, the notions of probability of many philosophers, from Descartes and Locke to Kant, recognizably rely on a stock of meanings with roots in Renaissance humanism and medieval scholasticism. The philosophers in question deviated notably from this stock, but so did their scholastic contemporaries. The modernization of probability therefore occurred along a broad front of schools, trends and traditions in the seventeenth century. It is instructive to relate the four medieval concepts of probability listed above to their modern successors. On the modern side, three major groups of interpretations or concepts of probability have emerged (Hájek 2011):