Blaise Pascal (1623-1662), a French mathematician, physicist, and religious philosopher, is most famous for what is now known as Pascal’s wager. The wager is a pragmatic argument for justifying a belief in God: "If you believe in God and turn out to be incorrect, you have lost nothing—but if you don't believe in God and turn out to be incorrect, you will go to hell. Therefore it is foolish to be an atheist." Scholars have keenly debated the intellectual and spiritual validity of Pascal’s wager for centuries. Pascal's contributions to the natural sciences include the construction of mechanical calculators, considerations on probability theory, studies of fluids, and clarification of concepts such as pressure and vacuum. The Pascal, the SI unit of pressure and vacuum, is named for him.