The general form of the problem is this: There is a runaway trolley barreling down the railway tracks. Ahead, on the tracks, there are five people tied up and unable to move. The trolley is headed straight for them. You are standing some distance off in the train yard, next to a lever. If you pull this lever, the trolley will switch to a different set of tracks. Unfortunately, you notice that there is one person on the side track. You have two options: (1) Do nothing, and the trolley kills the five people on the main track. (2) Pull the lever, diverting the trolley onto the side track where it will kill one person. Which is the correct choice?

Check out other work in the Life Of The Mind series here.

On March 23, 1994, a medical examiner viewed the body of Ronald Opus and concluded that he died from a gunshot wound of the head caused by a shotgun. Investigation to that point had revealed that the decedent had jumped from the top of a ten-story building with the intent to commit suicide. (He left a note indicating his despondency.) As he passed the 9th floor on the way down, his life was interrupted by a shotgun blast through a window, killing him instantly. Neither the shooter nor the decedent was aware that a safety net had been erected at the 8th floor level to protect some window washers, and that the decedent would most likely not have been able to complete his intent to commit suicide because of this.
Ordinarily, a person who starts into motion the events with a suicide intent ultimately commits suicide even though the mechanism might be not what he intended. That he was shot on the way to certain death nine stories below probably would not change his mode of death from suicide to homicide, but the fact that his suicide intent would not have been achieved under any circumstance caused the medical examiner to feel that he had homicide on his hands.
Further investigation led to the discovery that the room on the 9th floor from whence the shotgun blast emanated was occupied by an elderly man and his wife. He was threatening her with the shotgun because of an inter-spousal spat and became so upset that he could not hold the shotgun straight. Therefore, when he pulled the trigger, he completely missed his wife, and the pellets went through the window, striking the decedent.
When one intends to kill subject A but kills subject B in the attempt, one is guilty of the murder of subject B. The old man was confronted with this conclusion, but both he and his wife were adamant in stating that neither knew that the shotgun was loaded. It was the longtime habit of the old man to threaten his wife with an unloaded shotgun. He had no intent to murder her; therefore, the killing of the decedent appeared then to be accident. That is, the gun had been accidentally loaded.
But further investigation turned up a witness that their son was seen loading the shotgun approximately six weeks prior to the fatal accident. That investigation showed that the mother (the old lady) had cut off her son’s financial support, and her son, knowing the propensity of his father to use the shotgun threateningly, loaded the gun with the expectation that the father would shoot his mother. The case now becomes one of murder on the part of the son for the death of Ronald Opus.
Now comes the exquisite twist. Further investigation revealed that the son, Ronald Opus himself, had become increasingly despondent over the failure of his attempt to get his mother murdered. This led him to jump off the ten-story building on March 23, only to be killed by a shotgun blast through a 9th story window.
The medical examiner closed the case as a suicide.

Check out other work in the Life Of The Mind series here.

Suppose we agree that everyone has a right to life, but that a person forfeits this right when he threatens the life of another–in that case it’s permissible to kill him.
Now consider three people, A, B, and C. A aims a gun at B, B aims a gun at C, and C aims a gun at A. When A takes aim, he’s threatening another person, so he loses his own right to life. Normally in that case C would be justified in killing him, since this defends B. But B is aiming at C, which means he forfeits his own right to life, which means that A can kill him, and that C can’t kill A.

Check out other work in the Life Of The Mind series here.

Traps and Intuitions is a category belonging to The Life of the Mind that contains what are often referred to as thought problems. They create a story or choice in which the reader experiences conflict between ideas, or one that reveals the reader’s deeper intuitions. Intuitions that one might not be ready to acknowledge when asked directly.

Check out other work in the Life Of The Mind series here.

A person is playing a game operated by the Predictor, an entity somehow presented as being exceptionally skilled at predicting people’s actions. Predictor’s predictions are “almost certainly” correct.
The player of the game is presented with two boxes, one transparent (labeled A) and the other opaque (labeled B). The player is permitted to take the contents of both boxes, or just the opaque box B. Box A contains a visible $1,000. The contents of box B, however, are determined as follows: At some point before the start of the game, the Predictor makes a prediction as to whether the player of the game will take just box B, or both boxes. If the Predictor predicts that both boxes will be taken, then box B will contain nothing. If the Predictor predicts that only box B will be taken, then box B will contain $1,000,000.
By the time the game begins, and the player is called upon to choose which boxes to take, the prediction has already been made, and the contents of box B have already been determined. That is, box B contains either $0 or $1,000,000 before the game begins, and once the game begins even the Predictor is powerless to change the contents of the boxes. Before the game begins, the player is aware of all the rules of the game, including the two possible contents of box B, the fact that its contents are based on the Predictor’s prediction, and knowledge of the Predictor’s infallibility. The only information withheld from the player is what prediction the Predictor made, and thus what the contents of box B are. Question: do you take two boxes or one box?

Check out other work in the Life Of The Mind series here.

You have two groups of people. The people in group A have $1,000 each and the people in group B have $1,000,000 each. The only options available to you are to take away money from people in group B, so they each have $1,000, or to do nothing. Which would be the better course of action?

Check out other work in the Life Of The Mind series here.

“The ship wherein Theseus and the youth of Athens returned from Crete had thirty oars, and was preserved by the Athenians down even to the time of Demetrius Phalereus, for they took away the old planks as they decayed, putting in new and stronger timber in their place, in so much that this ship became a standing example among the philosophers, for the logical question of things that grow; one side holding that the ship remained the same, and the other contending that it was not the same.”
Plutarch, Theseus

Check out other work in the Life Of The Mind series here.