"Uhh, of course I am," you respond indignantly. "If I was fake, how would I be able to talk to you?"

The question is deeper than it appears. In fact, it is utterly loaded. When I ask you, "Are you real?" it begs several other questions. What is reality? Am I living in it? Who is the "I" in which I refer to when talking about myself? Am I a sole identity, or am I comprised of many?

If you still remain apprehensive, and believe the answer to be as plainly obvious as the nose on your face, imagine the following scenario, devised by the great philosopher Hilary Putnam. It is a thought experiment wellknown to philosophers and "The Matrix" fans alike:

Imagine a mad scientist has taken your brain, placed it in a vat, and plugged it into a supercomputer. He has so cleverly devised this computer; it inputs electrical signals to your brain and responds appropriately to those that you send back to it. The supercomputer simulates an entire reality. You think of moving your arm, and the supercomputer sends a visual and sensory representation of (what you believe to be) your arm moving. You think of tilting your head, and the computer deceives you into believing you have done so. In actuality, however, you never left the simulation.

If you, hypothetically, existed inside this simulation, would you be able to prove it? In other words, what evidence could you possibly garner to prove that you were living in reality as it actually exists?

If the scientist, as an act of benevolence, decided to take you out of his or her twisted experiment and put your brain back in your real body, which would be the real you? Would it be the you that lived in the simulation, or the you that exists outside of it? Would all the memories inside the simulation — of your character growth, your mistakes, your trials your successes — no longer belong to you? Or would they make up a very critical part of you?

A more grounded example — which is admittedly still abstract — toys with our conventional notions of identity. While we think of ourselves as a unitive being, located somewhere in our heads behind our eyes, our sense of self somehow results from the millions of different neurochemicals interacting with each other to perform different actions. There is no one place that a neuroscientist can point to — not one single neurochemical, nor brain groove, nor lobe — and say that they have found "you." There is no concrete evidence that "I" exist as a single entity, only that there is a body with a brain, and that that brain has a mind, and that that mind is able to think that it is "me."

So, again, let me ask you — are you real?