1. The trolley problem.
You’re walking next to a train track, when you notice there are five people tied to it. A train is hurtling towards them. There is a lever within your reach; if you pull it, you can divert the train onto another track that only has one person tied to it. Do you kill the one in order to save the five?
2. The fat man and the trolley problem.
You’re walking next to a train track, when you notice there are five people tied to it. A train is hurtling towards them. This time, there is no lever. There is a fat man next to the track. If you push him onto the track, his weight will stop the train, but he will die. Do you push him, killing the one to save the five?
3. The famous violinist problem.
You wake up to find yourself attached to a famous, unconscious violinist. You’re told that a group of music lovers kidnapped you in your sleep in order to plug your body into in the violinist’s body - a process that will save his life. If you unplug him, he will die. If you remain attached to him for nine months, he’ll survive. Are you morally obligated to give up control of your body for nine months? What if the violinist was an unborn child?
4. The ticking time bomb problem.
You are a senior law officer and a terrorist group has announced that it has hidden a nuclear bomb in your building. It will explode in half an hour, unless you stop it. You have caught the terrorist group’s leader, who knows where the bomb is but will not tell you. Torturing him is guaranteed to provide you with the information you need. Do you torture him to save the lives of everyone else in your building?
5. The problem of Theseus’ ship.
A ship’s sail breaks, so it is replaced. A year later, its floorboards start to rot, so they are replaced too. Eventually, each of the ship’s components is replaced and none of its original parts remain. Is it the same ship? The same thing happens to the cells in your body; every seven years every part of you is replaced. Are you the same person you were seven years ago?
6. The problem of Mary, the colourblind scientist.
Mary is a brilliant scientist. However, she can only experience the world from a black and white room via a black and white television monitor. She specialises in the neurophysiology of vision and has learnt every single fact that you can possibly read about colour. One day, Mary is released from her black and white room and sees colour for the first time. Does she learn anything new?
7. The problem of the cow in a field.
A farmer is worried that his prize cow has wandered off. When the milkman comes by, he tells the farmer not to worry, because he’s seen that the cow is in a nearby field. Just to double check, the farmer steps into the field, sees the familiar black and white shape of his cow, and is satisfied that he knows the cow is there. Later, the milkman drops by the field to double-check. The cow is there, but it’s hidden behind a bush. There is also a large sheet of black and white paper caught in a tree, and it is obvious that the farmer mistook this paper for his cow. Even though the cow was in the field, was the farmer correct when he said he knew it was there?
8. The Chinese room problem.
You are locked in a room. You know no Chinese, but you have a set of rules - in English - that enable you to correlate one set of Chinese symbols with another set of Chinese symbols. These rules allow you to respond, in written Chinese, to questions posed by native Chinese speakers. Basically, you are acting as a computer. Do you understand Chinese?
9. The experience machine problem.
There exists an experience machine that can give you the sensations of any experiences you desire. If you plug into it, you will spend the rest of your life floating in a tank with electrodes attached to your brain. But, you will be oblivious to this fact and will in fact believe that all of your dreams are coming true. Would you plug into it?