Abstract
In 1654, almost exactly three hundred years ago, the Chevalier de Mere, a mathematically inclined gamester, found himself in difficulties over the problem of dividing the gains in games of dice. So he sought the advice of the greatest mathematician of his time, Pascal; and started a train of thought which has led
the last three centuries, to the development of the important theory of probability. We may contrast the mathematical probability with the private or psychological world of subjective probability, based on partial or imperfect knowledge, and embodied in the daily perceptions, predictions and decisions of the individual. In spite of the fact that we constantly have to choose, estimate, judge, decide and act on partial or imperfect knowlege, the world
of private uncertainty remains largely
unexplored.
