Can you know that you have hands if you cannot rule out that you are a brain in a vat?
Every individual has, at some stage or another, pondered over questions such as “Am I real?”, “Is what I
see real?” or even “Am I the only living person, simply imagining everything and everyone else?”. If one
were a sceptic, one would have to conclude that although knowledge is possible, we have yet to acquire it.
We cannot know anything except, thanks to Descartes’
cogito ergo sum
argument, our own existence. For
nothing we see before us could not be reproduced in a dream-like illusion, and as such, since we cannot be
sure if we are dreaming or awake, it is impossible to say what is real and what is not. Descartes himself,
in his first
, states that his conclusion, that nothing can truly be known, creates an
“inextricable darkness” in life. However, this essay will argue that there are significant flaws in the
sceptics’ arguments, and that ultimately I can know that hands do exist.
For the purposes of this essay, the external existence of objects, in other words objects that are “outside of
our minds”, shall be taken to mean anything that can go on existing regardless of whether or not a person
is aware of it. For example, if one were to see a tree, then turn away, one trusts, if the object is external
and exists, that the tree is still there. Any other person, on passing, will perceive the tree in the same way,
having the same ‘sense data’, as Bertrand Russell puts it. But what type of objects does this definition
cover? Broadly, anything that may be interpreted or perceived by other people, and anything that could
exist without somebody being aware of it. This therefore includes any object, person, or even something
more abstract such as mathematics or music.
Hilary Putnam in 1981
introduced the argument that one could in fact be simply a brain in a vat (BIAV),
with an evil scientist or computer stimulating our nerve endings, creating the sensation that everything is
normal. Once I raise my two hands in front of my face, the scientist or computer responds, by creating the
right sights and feelings of the hand being raised. In this scenario, it could be true that everyone you come
across and communicate with really is simply a figment of the scientist’s imagination. One would be living