The Felicific Calculus

To value a pleasure or pain with precision, Bentham identifies seven circumstances that must be taken into account: its intensity; its duration; its certainty or uncertainty; its propinquity — how near in time it is; its fecundity — the chance it has of being followed by sensations of the same kind; its purity — the chance it is not followed by sensations of the opposite kind; and its extent — the number of persons affected.

For the purposes of moral and legal judgment, the procedure is to sum all the pleasures an act produces and all the pains it produces, then subtract the pain total from the pleasure total. If the balance is on the side of pleasure, the act is good; if on the side of pain, it is bad. Applied to legislation, this means that every law must demonstrate a positive utilitarian balance — that the suffering it imposes (through punishment or restriction) is outweighed by the harm it prevents.

Bentham is under no illusion that legislators can perform the calculus with precision in every case. Its value is not computational exactness but rational orientation — a reminder that the effects of law on human experience are the only legitimate ground of legislation. The calculus also reveals that many customary punishments are disproportionate, and that the proper measure of punishment is the minimum necessary to outweigh the temptation to offend.

The felicific calculus is developed in Chapter IV of the Introduction; its application to punishment is extended in Chapters XIII–XVI.