“The creed which accepts as the foundation of morals ... the Greatest Happiness Principle, holds that actions are right in proportion as they tend to produce happiness, wrong as they tend to produce the reverse of happiness. By happiness is intended pleasure, and the absence of pain; by unhappiness, pain and the privation of pleasure.""

"Suppose there were an experience machine that would give you any experience you desired. Superduper neuropsychologists could stimulate your brain so that you would think and feel you were writing a great novel, or making a friend, or reading an interesting book. All the time you would be floating in a tank, with electrodes attached to your brain ... Would you plug in? What else can matter to us, other than how our lives feel from the inside?"

"David is a great transplant surgeon. Five of his patients need new parts?one needs a heart, the others need, respectively, liver, stomach, spleen, and spinal cord?but all are of the same, relatively rare, blood-type. By chance, David learns of a healthy specimen with that very blood-type. David can take the healthy specimen's parts, killing him, and install them in his patients, saving them. Or he can refrain from taking the healthy specimen's parts, letting his patients die.

Edward is the driver of a trolley, whose brakes have just failed. On the track ahead of him are five people; the banks are so steep that they will not be able to get off the track in time. The track has a spur leading off to the right, and Edward can turn the trolley onto it. Unfortunately there is one person on the right-hand track. Edward can turn the trolley, killing the one; or he can refrain from turning the trolley, killing the five.

Frank is a passenger on a trolley whose driver has just shouted that the trolley's brakes have failed, and who then died of the shock. On the track ahead are five people; the banks are so steep that they will not be able to get off the track in time. The track has a spur leading off to the right, and Frank can turn the trolley onto it. Unfortunately there is one person on the right hand track. Frank can turn the trolley, killing the one; or he can refrain from turning the trolley, letting the five die.

George is on a footbridge over the trolley tracks. He knows trolleys, and can see that the one approaching the bridge is out of control. On the track back of the bridge there are five people; the banks are so steep that they will not be able to get off the track in time. George knows that the only way to stop an out-of-control trolley is to drop a very heavy weight into its path. But the only available, sufficiently heavy weight is a fat man, also watching the trolley from the footbridge. George can shove the fat man onto the track in the path of the trolley, killing the fat man; or he can refrain from doing this, letting the five die."

"Act in such a way that you always treat humanity, whether in your own person or the person of any other, never simply as a means, but always at the same time as an end."