Monthly Archives: January 2016

Raman, Thought Experiments

Brain in a Vat

Imagine that a mad scientist created a machine into which he could place a human brain. This machine, which we shall call a “brain vat”, would not only keep the brain alive and functioning, but it would allow the scientist to create virtual stimuli and feed them directly into the brain. The brain would register all of these stimuli in exactly the same manner as normal human sensory experiences, as these are already interpreted as electrical signals anyway. In this way, the scientist could create an entire fictitious world that, to the captive brain, would feel completely normal.

What if I told you that you, the person reading this post, were not actually a human being but instead merely a brain in a vat? You may attempt to prove me wrong, but you would find that quite difficult, and you would not be alone. This thought experiment has puzzled philosophers since it was first proposed in 1641 by René Descartes (Though Descartes’ experiment used an evil demon in place of a vat. The vat was proposed Gilbert Harman in 1973 to update the experiment to accommodate modern understandings of psychology and neuroscience). The idea of the brain in a vat (BIV) is that no brain could ever know whether it was in a skull or a vat, and could therefore never know whether everything it experiences is real or an illusion.

Descartes answered his own version of the experiment with his famous cogito, ergo sum (“I think, therefore I am”). I do not have the time or space to fully explain the Cogito in this post, but I highly encourage everyone to read about it. Essentially Descartes argues that either the world is real and he is experiencing it, or he is being deceived. Even if he is being deceived, he still exists in order to be deceived. Therefore, the fact that he can question his existence is sufficient to prove that he exists.

Importantly, the Cogito does not prove that he is not being deceived (or, to use the BIV terms, that he is not a brain in a vat). What Descartes instead proves is that he is something, not necessarily a human or even necessarily a brain, but something. Based on the Cogito, a BIV can know that it exists, but it cannot know anything else about itself or the world.

This thought experiment has implications for ethics (if you are a brain in a vat and nothing else is real, there is nothing wrong with doing terrible things to others), epistemology (the study of knowledge and what it means/why it matters), our understandings of what it means to be human, and many other philosophical disciplines. Many scientists have also written about and studied this thought experiment for a variety of reasons and in a variety of contexts.

On a lighter note, if this all sounded very familiar, it may be because this thought experiment is the basic plot of The Matrix (though the matrix also includes some elements of the experiment from last week’s post, The Allegory of the Cave). On an even lighter note, here are some funny cartoons about this thought experiment. Have a great weekend, even if it’s all an illusion!
BIV Cartoon

BIV Cartoon 2

(cartoons from https://coelsblog.wordpress.com/2014/08/14/a-scientific-response-to-the-brain-in-a-vat/.)

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Raman, Thought Experiments, Uncategorized

The Allegory of the Cave

Ok, so before I start commenting on specific thought experiments I want to stop and explain what thought experiments are and why they are important. Often times philosophers find themselves dealing with very conceptual, multifaceted questions that are too abstract and complex to meaningfully discuss. To get around this, they will often create thought experiments. Thought experiments, like science experiments, seek to isolate the variable being studied to allow for meaningful exploration. This usually takes the form of setting up a fictitious scenario in which people are confronted either with a purer form of the initial question or some allegorical situation.

To illustrate this, consider Plato’s famous “Allegory of the Cave” (or “Allegory of the Den” depending on the translation). In the allegory, Socrates (Plato’s teacher and the narrator of all of Plato’s dialogues) asks a friend named Glaucon to imagine that there are prisoners in a cave chained against a wall. Behind them there is a fire and a walkway (see image). Throughout the day, puppeteers walk down the walkway with puppets that cast shadows on the wall. The men can see the shadows, but they cannot see the objects themselves. If the shadow were of a book, the prisoners, knowing nothing else of books, would say that they see a book. We know that what they see is merely a shadow of a book, an approximation of the real object, but they would not understand this.

Socrates asks Glaucon to consider what would happen if a prisoner was released and able to see the sun and real objects in their true forms. Glaucon observes that he would likely be put-off at first, but that he would soon come to understand that these new objects were real and that the old ones were all shadows. Socrates then asks what the man would do if he was taken back into the cave and made to again watch the shadows. Glaucon points out that he would likely be frustrated by the triviality of it all, and that he would be especially incapable of trying to assign meaning to the shadows like the other men, since he would know that the shadows were not really the objects the men assumed they were.

Plato wants us to learn a few things from this allegory. Specifically, he trying to illustrate the life of people who do not understand his theory of forms. The theory of forms holds that the universe has a creator and that there exists only one of each object/concept in the world, which is located in the mind of the creator. According to Plato, the physical incarnations of these forms (the name given to the original object/concept) are merely copies of the forms and are therefore imperfect. Plato equates these copies to the shadows on the walls of the cave and himself to the man who has been let out to see the original objects, the forms.

While few people seriously believe his theory today, there is still much to be learned from the allegory. While Plato intended it to represent ignorance of the forms, it can really be used with any kind of ignorance. It is also commonly used to illustrate the concept that, while we develop perceptions of objects in our minds, these perceptions are distinct from the objects that created them and not all of our “knowledge” about these objects is correct.

Hopefully this has helped you to see how thought experiments can be useful in illustrating complicated concepts. I picked an easier one for the first post, but I will try to get into some more complicated and abstract ideas as the semester progresses. On a side note, I am trying to decide whether or not to discuss paradoxes on this blog. They have a completely distinct purpose from thought experiments, but they are also useful ways of thinking about tough questions and force readers to challenge their minds. If you have an opinion, let me know in a comment.

 

platoscave

https://faculty.washington.edu/smcohen/320/cave.htm

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