The Reality of Reality: the Brain-in-a-Vat Thought Experiment

Throughout history, society has flirted with the premise of human reality being engineered by an external force. Whether it be The Matrix, Avatar, or Inception, the question of an external reality has constantly hounded prominent thinkers and been reflected in mainstream media. But from where did such a premise stem? Is it true? How can we apply it to the real world?

Brain in a Vat

A thought experiment, as defined by the community of philosophy, is a hypothetical scenario, or “experiment”, with a purpose to challenge the brain– whether it be to educate, entertain, or explore. They often tread ill-defined themes such as morality or knowledge, and are analyzed in a variety of disciplines and by a variety of professions.

The Brain in a Vat thought experiment posits that a given person is not a true person but a disembodied brain in a vat of nutrients. To the person, all appears as regular; experiences are lived through as we would, emotion is felt as we would. This hypothetical person is capable of accumulating memories, forming thoughts and opinions, and developing relationships. However, the divergence from our conception of the average person lies in the truth of the person’s reality. Though they experience memories and events as lively as if they were reality, the person’s true reality is that of a disembodied brain in a vat.

To analogize, human dreams are notorious for the perceived realism of the experience– the horror of nightmares and the bliss of soothing dreams stem from such realism. However, like the disembodied brain, at the end of the day, dreams are not rooted in reality. This is the thought experiment of the Brain in a Vat; a conundrum for skeptics to question whether our reality can be called a reality, even if it is ultimately a simulation.

Background

The first, primitive form of the Brain in a Vat thought experiment was first produced by Rene Descartes in 1641. Labeled the “Evil Demon” experiment, Descartes proposed that one’s actions, thoughts, and opinions were all engineered by an evil, third-party demon that would misguide and mislead human beings. Descartes’ response, then, was his renowned phrase “I think, therefore I am. (Cogito ergo sum.)” He posited that insofar as an individual was aware of one’s own thinking, it was indubitable that not everything was under doubt. Yet Descartes’ early work was lacking in its engagement with the question of reality versus simulation, taking a focus on determining a foundation for knowledge.

Later on, the American philosopher Gilbert Harman refined the details of Brain in a Vat in his book Thought (1973). Subsequently, Hilary Putnam developed an unconventional argument to refute the scenario. Putnam constructed the refutation with semantic externalism at its base; he suggests that, assuming each person was simply a brain in a vat, any singular word cannot correspond to the real, external concept it means to represent. For example, a brain in a vat has no way of knowing what a real tree is since it is simply a brain in a vat of juice– yet it uses the term “tree” nonetheless, meaning it cannot connect the term to the real concept. And Putnam’s refutation says that if we are brains in vats, we cannot think, say, or know that we are brains in a vat, because we would not know what a true brain or vat is. Therefore, we cannot be brains in a vat. 

Putnam possessed multiple other refutations, but the semantic externalist argument is the most well-known.

Real Life Applications

Though the practical, applicable usages of the Brain in a Vat thought experiment seem scant, its impact runs far deeper than many superficially observe. In literal terms, the Brain in a Vat thought experiment is likely unfeasible and matters not; if we truly were brains in vats, 1) the brain would be incapable of sustaining itself disembodied, even with nutrient-rich liquid, due to biological restraints and a dependency on the rest of the body, and 2) it would not matter, as reality is still reality as we perceive it to be and the truth of an undetermined “external” world does not affect our perception in any way.

However, the purpose of Brain-in-a-Vat is not to prove that we are brains in vats, but rather to highlight the uncertainty of our knowledge– that there is no way to prove we are individuals with full agency, uninhibited by any external force. Brain-in-a-Vat utilises skepticism to challenge many modern predisposed notions. For example, on the question of free will, one may wonder if free will exists when one’s community, financial situation, and upbringing shape them in unique and incontestable ways. As well, one may consider the depths of what they do not know– both what they know they do not know and what they do not know they do not know. The diverging branches of thought which stem Brain-in-a-Vat are indispensable to modern policy-making, techniques used in therapy, and a variety of industries; for example, in considering free will, governments may minimise biases through public education, or for questions on the unknown, researchers may be prompted to discover that which they do not know they do know.

Conclusion 

Brain-in-a-Vat has birthed considerable discourse in philosophy discussions– ranging from its validity as a thought experiment, to feasibility, to the question of skepticism it brings. Though one conclusive answer has yet to be agreed upon, that is where the beauty of the thought experiment lies; a multi-dimensional question, received differently by each person. Brain-in-a-Vat introduces skepticism to the numbed masses, deconstructing echo-chambers and facilitating the clash of skeptics and realists.