Thought experiments are mental concepts or hypotheses, often resembling riddles, which are used by philosophers and scientists as simple ways of illuminating what are usually very dense ideas. Most often, they’re used in more abstract fields like philosophy and theoretical physics, where physical experiments aren’t possible. They serve as some hearty food for thought, but given their complex subject matter, it’s not unusual for even the thought experiment itself to be nearly incomprehensible. With this in mind, here are ten of the most famous thought experiments, along with explanations of the philosophical, scientific, and ethical ideas they work to explain:
One of the most well known thought experiments in the field of ethics is the “Trolley Problem,” which goes something like this: a madman has tied five innocent people to a trolley track. An out of control trolley car is careening toward them, and is moments away from running them over. Luckily, you can pull a lever and divert the trolley to another track. The only problem is that the madman has also tied a single person to that track. Considering the circumstances, should you pull the lever?
What it Means:
The trolley problem was first proposed by the philosopher Philippa Foot as a means of critiquing the major theories in ethical philosophy, in particular utilitarianism, the system which proposes that the most moral decision is always the one that provides “the greatest good for the greatest number.” From a utilitarian point of view, the obvious choice is to pull the lever, saving five and only killing one. But critics of this theory would state that in pulling the lever you become complicit in what is clearly an immoral act—you are now partially responsible for the death of the lone person on the other track. Others, meanwhile, argue that your mere presence in the situation demands that you act, and that to do nothing would be equally immoral. In short, there is no wholly moral action, and this is the point. Many philosophers have used the trolley problem as an example of the ways that real world situations often force individuals to compromise their own moral codes, and that there are times when there is no totally moral course of action.
One of the major thought experiments in epistemology (the field of philosophy that deals with knowledge) is what is known as “The Cow in the Field.” It concerns a farmer who is worried his prize cow has wandered off. When the milkman comes to the farm, he tells the farmer not to worry, because he’s seen that the cow is in a nearby field. Though he’s nearly sure the man is right, the farmer takes a look for himself, sees the familiar black and white shape of his cow, and is satisfied that he knows the cow is there. Later on, the milkman drops by the field to double-check. The cow is indeed there, but it’s hidden in a grove of trees. There is also a large sheet of black and white paper caught in a tree, and it is obvious that the farmer mistook it for his cow. The question, then: even though the cow was in the field, was the farmer correct when he said he knew it was there?