Jeremy Bentham (1748-1832) devised utilitarianism, which is best captured in the John Stuart Mill's phrase “the greatest amount of happiness altogether” (Chapter II of Utilitarianism).
From Bentham's facile philosophy grew the ludicrous notion that it might be possible to quantify each person's happiness and, then, to arrive at an aggregate measure of total happiness for everyone (or at least everyone in England). Utilitarianism, as a philosophy, has gone the way of Communism: It is discredited but many people still cling to it, under other names.
Modern utilitarianism lurks in the guise of cost-benefit analysis. Governments often subject proposed projects and regulations (e.g., new highway construction, automobile safety requirements) to cost-benefit analysis. The theory of cost-benefit analysis is simple: If the expected benefits from a government project or regulation are greater than its expected costs, the project or regulation is economically justified.
Cost-benefit analyses is deeply flawed in two ways. In the first instance, it’s a simple matter for the proponents of a government program to jigger the numbers to proved that a project is justified economically. (The ease with which numbers can be jiggered is illustrated here, here, and here.)
The second flaw is fundamental, but ignored: One person's benefit can't be compared with another person's cost. Suppose, for example, that the City of Los Angeles conducted a cost-benefit analysis that "proved" the wisdom of constructing yet another freeway through the city in order to reduce the commuting time of workers who drive into the city from the suburbs.
Before constructing the freeway, the city would have to take residential and commercial property. The occupants of those homes and owners of those businesses (who, in many cases would be lessees and not landowners) would have to start anew elsewhere. The customers of the affected businesses would have to find alternative sources of goods and services. Compensation under eminent domain can never be adequate to the owners of taken property because the property is taken by force and not sold voluntarily at a true market price. Moreover, others who are also harmed by a taking (lessees and customers in this example) are never compensated for their losses. Now, how can all of this uncompensated cost and inconvenience be "justified" by, say, the greater productivity that might accrue to those commuters who would benefit from the construction of yet another freeway.
Yet, that is how cost-benefit analysis works. It assumes that group A's cost can be offset by group B's benefit: “the greatest amount of happiness altogether”. To put it more crudely, the pleasure A obtains when he punches B’s nose cannot compensate B for the pain and humiliation he suffers at A’s hands.