Bentham's Utilitarianism and the Felicific Calculus

In one line

Bentham says pleasure and pain govern everything we do and everything we ought to do, and that morals and legislation can therefore be put on a footing as exact as arithmetic.

In the wording a student can write in an exam: Bentham holds that nature has placed mankind under the governance of two sovereign masters, pain and pleasure, which alone point out what we ought to do and determine what we shall do; that the principle of utility, which approves or disapproves of every action according to its tendency to augment or diminish happiness, is therefore the only defensible standard of right and wrong; and that the value of any pleasure or pain can be estimated by seven measurable dimensions, so that legislation can be made a matter of calculation rather than of custom, sentiment or authority.

The opening, in Bentham's own words

The first sentence of chapter I is the whole doctrine compressed.

Nature has placed mankind under the governance of two sovereign masters, pain and pleasure. It is for them alone to point out what we ought to do, as well as to determine what we shall do. On the one hand the standard of right and wrong, on the other the chain of causes and effects, are fastened to their throne. They govern us in all we do, in all we say, in all we think; every effort we can make to throw off our subjection will serve but to demonstrate and confirm it. In words a man may pretend to abjure their empire, but in reality he will remain subject to it all the while.

Two claims are packed into that and they must be separated, because a student who runs them together cannot answer the standard objection.

A psychological claim. People are in fact moved by pleasure and pain. This is psychological hedonism.

A moral claim. Pleasure and pain are also the standard of right and wrong. This is ethical hedonism.

The standard objection is that the second does not follow from the first: that people are moved by something does not show it is what they ought to pursue. That is the naturalistic objection and Bentham does not answer it.

What Bentham was against

His doctrine is best understood by what he rejected, and each rejection is a target he names.

Natural rights. Bentham regarded them as nonsense, and imprescriptible natural rights as nonsense upon stilts. A right, for him, is the creature of law: to say that a right exists before any law confers it is to mistake what one wants for what is.

The social contract. A fiction. What the state actually rests on is the habit of obedience, and the question is whether obedience produces more happiness than resistance.