Full Idea
Pascal knows that one cannot decide to believe in God, but he thinks one can act so that one will very probably come to believe in God, by following a life of 'holy water and sacraments'.
Gist of Idea
Pascal knows you can't force belief, but you can make it much more probable
Source
report of Blaise Pascal (Pensées [1662], 418 (233)) by Ian Hacking - The Emergence of Probability Ch.8
Book Reference
Hacking,Ian: 'The Emergence of Probability' [CUP 1975], p.66
A Reaction
This meets the most obvious and simple objection to Pascal's idea, and Pascal may well be right. I'm not sure I could resist belief after ten years in a monastery.