Descartes - Methodological Doubt

Descartes Meditation I. title "Of the things which may be brought within the sphere of the doubtful." sums up the theme of this blog. Other ways of looking at it are to ask how firm are the foundations of our knowledge ? Yet another way is to look as laying down the foundations of Rationalist epistemology. 

Rationalists believe that our knowledge comes from axioms (things that are beyond doubt) and a deductive process as opposed to Empiricists who believe that all knowledge comes from senses.

Descartes is keen to lay down firm foundations of knowledge and accordingly in first meditation lists three major problems that need to be overcome.

1. Perceptual Illusion
Our senses are sometimes prone to errors a sttraight stick inserted into water appears bent . In mirages we see water where there is none.

Descartes however believed "sensory knowledge on the whole is quite sturdy."


2. The Dream Problem
There is very little to distinguish between dreaming and waking state experience because the dreaming state appears super real. This is what our man says "At the same time I must remember that I am a man, and that consequently I am in the habit of sleeping, and in my dreams representing to myself the same things or sometimes even less probable things, than do those who are insane in their waking moments.How often has it happened to me that in the night I dreamt that I found myself in this particular place, that I was dressed and seated near the fire, whilst in reality I was lying undressed in bed!"

 Even when a painter creates an imaginary creature, like a mermaid, the composite parts are drawn from real things—women and fish, in the case of a mermaid. Descartes believed that it is important to ensure that the individual parts constituting the composite  like shape, quantity, size, time, etc.  be on firm footing. He  felt that these lay in simple things, like arithmetic and geometry.


3. A Deceiving God

Descartes  considers a radical hypothesis of "deceiving God". What if there is an omnipotent god, but that deity devotes its full attention to deceiving people?  The problem here is not merely that people might be forced by god to believe what something which is in fact false. Descartes indicates  the far more devastating possibility that whenever people believe anything, even if it has always been true up until now, a truly omnipotent deceiver could at that very moment choose to change the world so as to render their 
belief false. On this supposition, it seems possible to doubt the truth of absolutely anything you and I might come to believe.

Since God is good and kind,  Descartes supposes that not God, but some evil demon has committed itself to deceiving him so that everything he thinks he knows is false.

His solution - Doubt everything so that  one can be  sure, not to be misled into falsehood by this demon.This is the theme of this blog.

This is what he says at the start of meditation IV
"I needed to do the exact opposite—to reject as if it were absolutely •false everything regarding which I could imagine the least doubt, so as to see whether this left me with anything entirely indubitable to believe. 
Thus,
•I chose to suppose that nothing was such as our senses led us to imagine, because our senses sometimes deceive us. Also,
•I rejected as unsound all the arguments I had previously taken as demonstrative [= ‘absolutely rigorous’] proofs, because some men make mistakes in reasoning, even in the simplest questions in geometry, and commit logical fallacies; and I judged that I was as open to this as anyone else. Lastly,•I decided to pretend that everything that had ever entered my mind was no more true than the illusions of my dreams, because all the mental states we are in while awake can also occur while we sleep ·and dream·, without having any
truth in them.

The most famous quote from Descartes is  "cogito, ergo sum" ("I think, therefore I am"). It affirms  the  intuition of one's own reality, an expression of the indubitably of first-person experience and the logical self-certification of self-conscious awareness in any form.

"I am thinking, therefore I exist was so firm and sure that not even the most extravagant suppositions of the skeptics could shake it, I decided that I could accept it without scruple as the first principle of the philosophy I was seeking."

"I think, therefore I am" makes mind more certain than matter, and my mind (for me) more certain than the minds of others. There is thus, in all philosophy derived from Descartes, a tendency to subjectivity.

The cogito enables the C & D (clear and distinct) argument the indubitable propositions from which other knowledge can be deduced by proper reasoning

"For after all, whether we are awake or asleep, we ought never to let ourselves be convinced except by the evidences of our reason. Note that I say ‘our reason’, not ‘our imagination’ or ‘our senses’. Even though we •have a vividly open view of the sun, we mustn’t judge on that account that it is only as large as we see it; "

from https://en.wikipedia.org/wiki/Cartesian_doubt
Descartes' method of hyperbolic doubt included:

1. accepting only information you know to be true
2. breaking down these truths into smaller units
3. solving the simple problems first
4. making complete lists of further problems

Here are two objections from http://people.tamu.edu/~sdaniel/Notes/descar1.html

• Even to raise the possibility that our experiences might not accurately describe a world that exists apart from our experience is already to assume that the distinction of world vs. experience makes sense. But what if the things we experience are not in fact ideas at all, but are rather things in the world themselves? The method of doubt proposes that it makes sense to think of ideas or beliefs apart from how they are ideas or beliefs about a world. But apart from the assumption of an external world, it makes no sense to think of ideas as distinct from that world.
• If we doubt everything, we also must doubt whether we are truly doubting. But that gets us into an endless regress (doubting that we are really doubting that we are really doubting and so on). So the effort to reach an indubitable principle through doubt is doomed from the outset. The only way to find out that we are correct in doubting is to appeal to a public understanding of what doubt means, and that means assuming that there is a really existing world.

I summarize by quoting Bertrand Russel (History of western philosophy )

"The method of critical doubt, though Descartes himself applied it only halfheartedly, was of great philosophic importance. It is clear, as a matter of logic, that it can only yield positive results if skepticism is to stop somewhere. If there is to be both logical and empirical knowledge, there must be two kinds of stopping points: indubitable facts, and indubitable principles of inference.Descartes's indubitable facts are his own thoughts--using "thought" in the widest possible sense. "I think" is his ultimate premise."