Okay, the argument. Let's get to it.
First, we have to establish that we exist. How do we do that? Descartes put it best: "I can doubt everything, except one thing, and that is the very fact that I doubt." We know we exist because we have thoughts. Put another way: we have self-awareness.
There is the brain-in-the-vat argument that goes: You are nothing but a brain in a vat of solution in the laboratory of a mad scientist (the same guy who created the human centipede). He dumps various chemicals into the solution and shoots voltage through it and this causes you to have various sensations--sitting on a beach in Waikiki watching the sunset as the waves gently lap the shore, running down a dark alley for your life from a knife-wielding maniac with your adrenalin pumping and your heart in your throat, having hot belly-rubbing sex with the person of your wildest fantasies, sitting in a chair in front of your computer reading this post, etc. None of it is really happening. It's nothing but an electro-chemical reaction in your suspended brain being stimulated by a madman. How could you prove you are really where you believe you are, who you are, what experience tells you what and where you are and not simply a brain in a vat? You can't. You must doubt all your experiences, sensations, memories, beliefs. But you can't doubt that, in some way or other, you exist.
"And now, Igor, we put the lime in the coconut!"
And what is the agency responsible reaching this conclusion? In a word--consciousness. You are a conscious being. So let's define consciousness in an experiential way that we can all understand and relate to:
I. I experience.
II. I know I experience because I remember my experiences.
III. I can also remember remembering my experiences.
IV. I can remember some experiences as many times as I wish--an infinite number of times theoretically.
V. How many experiences must I remember to be conscious? All of them.
That's it. Simplistic but to the point. These are the bare minimum requirements in order to be conscious. You can add more but it makes no difference here. You can't take any of them away, however. But most importantly, they are
a priori or self-evident. I don't want to get into long discourses on dualism and materialism. This clutters the landscape unnecessarily. Let's keep it simple and see where it takes us.
Okay, what is an experience? There are two kinds--inward and outward. Or those that happen within the mind of the experiencer and those that happen outside. For now, we are only interested in those that happen outside or what we call external events.
When you sense an event, you have an experience, right? Not quite. You must have a memory of the event that you sensed. Why? Because without it, can you know you had the experience? Or, more properly speaking, was it experience at all? Suppose, we are standing on opposite sides of the street and two cars collide in the street between us. I look at my watch and yell across to you that the accident occurred at 4 pm. An hour later, you say to me. "At 4 pm today, we witnessed a collision of two cars in the street."
But suppose I was drunk at the time and in a blackout mode and now say, "Sorry but I don't remember that at all."
Even though I witnessed the accident and even noted the time, without a memory of that event, did I experience it? Now you might say, "Yes, you were there." (The empirical view) But that doesn't matter to me--I don't have any recollection whatsoever of this event. I may as well have not been there. Without memory, I have no experiences.
Hence, my experiences are a chain of memories of events. I live in the same area I grew up in but I spent 6 years in the armed forces traveling much of the world. I was changed so much by those experiences that I am not the person I was before I left town/the state/the country. But if I could not remember anything of my travels would I be any different than before I left? No.
Moreover, if I lost the memory of all my travels and everything I encountered during those travels would I just have this 6-year gap of no memories? No, I couldn't or I would be remembering something--namely, a period of no memories. In other words, my consciousness is continuous. It has no gaps in it. If I lost the memories of my travels the day after I returned to town, it would seem to me as though I never left. Instantaneously, 6 years just went by. You can't remember having no memory. To be aware of nothing means you cannot even be ware of the passage of time or you would be aware of something. CONTRADICTION.
Ok, let's break here. I have things I have to do and I want to make you sure you understand what I have said here. If you have questions, ask away.