What is a Thought Experiment?

A thought experiment is a cognitive tool that is deployed in order to:

• Understand our intuitions
• Test our consistency
• Reveal assumptions
• Question the principles underlying an argument or claim

Most often these cognitive tools take the shape of hypothetical scenarios, where we are asked to consider some imaginative scenario and provide an answer on what we think the right answer is. In doing so, we can clarify our thinking on certain topics, questions, and ideas to see where our philosophical commitments lay; or, we can develop a counterargument to the thought experiment and explain why it does not demonstrate what it says it does.

Ethics is a domain of philosophy that is ripe for the imaginative person to develop all sorts of unique and crafty thought experiments. However, thought experiments are not only limited to philosophy and can be utilized in various areas of study to achieve similar goals that philosophers have in mind when they use them.

When and How to Use a Thought Experiment

Although they provoke interesting questions and stimulate discussions, thought experiments require careful and critical thought before they can be used effectively. Remember — thought experiments are not always counterfactuals to arguments. While it may seem that a philosopher’s argument can be easily refuted by a well developed thought experiment, the consequences of that thought experiment may be perfectly acceptable to them. In such a case, a philosopher may have already accepted the consequences of their view and is prepared to argue for them; hence, the thought experiment falls flat on its face.

In order to use a thought experiment successfully, it must be able to show why it reveals a weakness in that philosophers argument and why your solution is preferable to theirs. There needs to be an argument accompanying the thought experiment to show why the outcome is more preferable than the other philosopher’s alternative. Thought experiments work best when used to show that the kinds of conclusions a philosopher’s argument creates lead to inconsistencies or unethical views in their position.

Consider the following:

• The Trolley Problem
  • A train is moving down the track and fast approaching a split in the track. On one side is a person tied to the track, and on the other are five people on the track. The train is currently on a path to hit and kill the five people on the track. In front of you is a lever that can divert the direction of the train the other way, where there is only one person tied on the track. Should you pull the lever?

Broadly speaking, those who are philosophically committed to the ethical theory of Utilitarianism would say that you have a moral obligation to the pull the lever to save the lives of five people. But now, consider the following thought experiment, which makes the Utilitarian answer to this thought experiment seem unethical:

• • A train is moving down the track and fast approaching a split in the track. The train is currently on a path to hit and kill the five people on the track. In order to save the lives of the five people, you must push an unknown bystander in front of the train to stop it from moving. Should you push the unknown bystander?

While it is possible the utilitarian might ‘bite the bullet‘ so to speak and push the bystander, we might wonder if it is truly ethical to directly harm other people in order to save the lives of others. Can we really say the Utilitarian theory offers us the right thing to do in this case, or might other ethical theories have better ways to solve this dilemma?

Thought experiments are abstract, but the principles and conclusions they lead us towards do not need to be. If the above thought experiment shows that the Utilitarian is okay with harming the few to save the many, then what might they also say about the rights of minorities and immigrants against the majority when they conflict? Historical examples can also be used as more empirically based thought experiments to see what is at stake in certain ethical theories. The key point to remember here is that the importance of thought experiments is in their ability to take the underlying principle and generalize it to broader ethical concerns.

A Final Word on Thought Experiments

As you read the various chapters in this book, you will encounter thought experiments that both support and reject the principles put forward by the philosophers in each chapter. Each one is designed to help you think more clearly and carefully about the arguments being put forward. Remember, thought experiments are great points of discussion with others and are great fun when you can come up with your own and share them with others.

Check out the Absurd Trolley Problems game by Neal Agarwal to try out different varieties of the trolley problem, and see if you can explain why you would or would not pull the lever.

How to Cite This Page

Aiken, Hunter. 2024. “A Primer on Thought Experiments.” In Introduction to Ethics, edited by Jenna Woodrow, Hunter Aiken, and Calum McCracken. Kamloops, BC: TRU Open Press. https://introductiontoethics.pressbooks.tru.ca/chapter/a-primer-on-thought-experiments/.