Philosophy Club

Descartes: The First Meditation

Introduction

The French philosopher Rene Descartes was one of the greatest philosophers who ever lived. He was born in 1596 and died in 1650. In the Meditations on First Philosophy his main concern was with the question: What can be known with absolute certainty? In the First Meditation he aims to discover secure foundations for all knowledge, and introduces the "Method of Doubt". This method involved putting all of his beliefs to the following test: For any belief, can it be doubted? If it can, then it must be rejected just as if it were false. If it can't, then the belief in question is indubitable and hence certain, and therefore worthy of serving as a foundation of knowledge.

In the First Meditation Descartes produced three main arguments.

1. The argument from the fallibility of the senses
   
   
   1. The senses have sometimes deceived me.
   2. If the senses have deceived me on some occasions, then they may be deceiving me on every occasion.
   3. Therefore the senses cannot be relied on to yield knowledge.

   Descartes comments on this argument, stating that the conclusion is not warranted in many cases. For surely the senses can't be deceived, for example, about whether or not I am sitting by the fire or holding paper in my hands. This leads Descartes to the second of the three arguments, the argument from dreaming.

   
   
   

   The argument from dreaming

   1. For any given perceptual experience E (e.g. that I am sitting here by the fire), I have no way of knowing whether or not E is part of a dream.
   2. So any given experience E could be part of a dream.
   3. If E is part of a dream then my beliefs concerning E are false (it would be false that I am sitting by the fire).
   4. Therefore for any given perceptual experience E, we can never know whether the beliefs concerning E are true.

   Descartes comments further that even if the dreaming argument established that we could not be absolutely certain about any of our perceptual beliefs, it would not affect our beliefs regarding logic, mathematics and other abstract beliefs. Is it possible to doubt even these? He finally introduces the third argument, the evil demon argument.

   The evil demon argument

   1. It is possible that there is a supremely powerful, intelligent and evil demon who deceives me about absolutely any of my beliefs.
   2. So for any belief of mine it is possible that I am being deceived and that what I believe to be true may be false.
   3. Therefore I cannot be certain about any of my beliefs.

Some questions

Argument (1)

1. My senses may deceive me into believing that a stick placed in a glass of water is bent. However, don't we actually rely on sense experience to establish that I was deceived? For to establish that the stick is straight I take it out of the water and observe it to be straight. So is Descartes' argument self-defeating?
2. Just because sense perception deceives us sometimes, why should we never trust them?

Argument (2)

1. Is premise (1) true? Is it true that we have no way of distinguishing between being asleep and dreaming and our experiences while awake?

Argument (3)

Since the evil demon may be deceiving us even about logic and mathematics, perhaps we are being deceived about Descartes own arguments. Might we be being deceived about the reasoning in argument (3) itself? For instance, might we be deceived into thinking that the conclusion of the argument "I cannot be certain about any of my beliefs" follows logically from the premises (1) and (2)? How could we argue for scepticism at all since the evil demon may be deceive us about the validity of our argument? Even if we were arguing validly we could never know it.

Reference

R. Descartes, Philosophical Writings (Translated by E. Anscombe and P. Geach).

R. Neurath