The felicific calculus is an algorithm formulated by utilitarian philosopher Jeremy Bentham (1748–1832) for calculating the degree or amount of pleasure that a specific action is likely to induce.
Bentham, an ethical hedonist, believed the moral rightness or wrongness of an action to be a function of the amount of pleasure or pain that it produced.
Begin with any one person of those whose interests seem most immediately to be affected by it: and take an account, To make his proposal easier to remember, Bentham devised what he called a "mnemonic doggerel" (also referred to as "memoriter verses"), which synthesized "the whole fabric of morals and legislation": Intense, long, certain, speedy, fruitful, pure— Such marks in pleasures and in pains endure.
The first major work in the field was an 1881 publication of Mathematical Psychics by the famous statistician and economist Francis Ysidro Edgeworth, who hypothesized a way of measuring happiness in units.
Since practical experience teaches otherwise (enjoyment form a meal does depend on the of courses), followers of Bentham argued that the order of episodes changes their intensity.