Is my brain really in a vat? Are my senses deceiving me?

I briefly touched upon this subject in my introduction to philosophy course with Coursera and now it’s come up again in Know Thyself. It fascinates and intrigues me so I have decided to look at it more closely. The basic concept is that we can’t prove that we aren’t simply brains in vats being fed experiences. Ridiculous you might say, but prove it’s not true. You can’t. And if this is the case how can we be sure what we believe is true. Do we really know anything?

Descartes discusses this issue in his meditations of first philosophy published in 1641. This is a process he undertook where he basically discarded all the beliefs he held before of which he couldn’t be certain, and then tries to establish what he can be sure of.

SEVERAL years have now elapsed since I first became aware that I had accepted, even from my youth, many false opinions for true, and that consequently what I afterward based on such principles was highly doubtful; and from that time I was convinced of the necessity of undertaking once in my life to rid myself of all the opinions I had adopted, and of commencing anew the work of building from the foundation, if I desired to establish a firm and abiding superstructure in the sciences. But as this enterprise appeared to me to be one of great magnitude, I waited until I had attained an age so mature as to leave me no hope that at any stage of life more advanced I should be better able to execute my design.

Meditation 1 of Meditations on first philosophy, Rene Descartes

What an amazing task to undertake. To decide that maybe everything you knew may not be true and to sit down and look at your beliefs and try and establish what you can be certain of, if anything.

He asks whether our senses, or even a mischievous god, deceive us into believing things. Most of us have experienced this at some point. Maybe experiencing a dream so vivid that it feels like it is happening whilst you are awake. Or perhaps having our minds messed with by our devious senses. I recently watched an episode of QI (comedy quiz show on the BBC) and saw something that still scrambles my mind to this day. See for yourself

I started looking at other optical illusions, this one for example, or this one and it made me think how easily we can be fooled and can’t rely 100% on our senses. Our memory plays tricks on us too. So it would appear our whole being is out to deceive us. So if we can’t rely on our beliefs, senses or memory what else is left? And if the answer is nothing how can we be sure that we aren’t brains in vats?

I look forward to reading Descartes’s meditations but hope that I am not a brain in a vat as I would like to think that I really am experiencing the things I am experiencing and not just being fed them by some evil scientist. But then again, if I don’t know that I am a brain in vat does it matter if I am a brain in a vat?