In Descartes Meditations he discusses knowledge, what true knowledge is, and what can truly be known. He does this by doubting everything he knows. This leads him to a line of argument about reality and dreams. He says it is almost impossible to doubt that he is, “sitting before the fire, wearing a dressing gown, that I hold in my touching this paper.” (Meditation I, 136) But he also argues that the senses can be misleading writing,
“How often a dream has convinced me that I was here, sitting before the fire, wearing my dressing gown, when in fact I was undressed and between the covers of my bed… When I think very carefully about this, I see so plainly that there are no reliable signs by which I can distinguish sleeping from waking…”(Meditation I, 137)
He uses this idea to bring into doubt the physical world and the faculty of the senses.
What is it to know you are dreaming? What is it that makes me accept my awakened state as reality? Descartes suggest that the dream state is a composite of reality, a reflection in a warped mirror. He says, “things like eyes, heads, hands, and bodies are not imaginary, but real. For even when painters try to give bizarre shape to sirens, they are unable to give them completely new natures.” (Meditations I, 137)
There seems to be some underlying difference between reality and dreaming. Some of these differences can be categorised as memory and impossibility. When we awake from a dream, as real as it seems, we soon forget the details of said dream. We seemingly forget something that we thought was real almost instantaneously. When we are ‘awake’ we have a connected memory from moment to moment stringing our lives together.
But why do we place so much faith in memory as a means of distinguishing reality? Memory is unreliable. No one person has a complete memory from conception to the present. Memory is selective, and it can lie to you, imagining something that didn’t occur and filling in minor details.
Memory while being somewhat unreliable is still the way we construct and live in ‘reality’. (Perry, 366) Without memory we would live a mindless existence. Therefore, just because it is unreliable doesn’t mean it can be dismissed.
The second distinguishing feature between dreams and reality is what is possible and impossible. Dreams seem to be created in a world with no laws. No laws of physics, biology, time or place. Your dreams seem to have no limit as opposed to reality which outwardly has limits and laws of reality. Reality is perceived to have a continual, almost linear aspect to its knowledge and existence whereas this is not always the case in a dream.
This is something that Descartes suggest can be called into doubt, because if the sense faculties are unreliable then the physical world is unreliable. (Meditations I, 137) This could be exemplified in eye tricks or mind puzzles. Also, ‘Reality’ has had fundamental shifts throughout history because of humanities acceptance of knowledge as reality. Take for instance the world being flat. For a long time people thought they could sail off the edge of the world. A whole wealth of knowledge was based on the idea that the world was flat and the idea that it was round was ridiculed. So the difference between the dream and reality in this aspect is that when you dream there is no enforced expectation or assumption of knowledge whereas reality is the opposite. You don’t question that you are dreaming when you are dreaming, only when you are awake.
But then knowledge can be continual if it is not perceived. Descartes suggest that the laws of mathematics cannot be proved false in a physical world. “Whether we are awake or we are asleep, two plus three is always five… It seems impossible even to suspect such obvious truths of falsity.”(Meditations I, 137)
The perception of dreams as having a separate identity to reality can be called into doubt as the belief that separates the two is based on false assumptions.
Descartes, René (1985), ‘Meditations on First Philosophy I and II’ in Introduction to Philosophy, ed. Perry. J, Bratman. M, Fischer. JM. pp. 116-121.
Perry, John (1983), ‘A Dialogue on Personal Identity and Immortality’ in Introduction to Philosophy, ed. Perry. J, Bratman. M, Fischer. pp. 368-88