Rene Descartes

1. Descartes thought we should push our doubts to absurdity, until they rebound and acquire indubitability. Hence, his Meditations ...

2. The SQUASHED Version I: Many of the things I used to be certain of, I now know to be nonsense... II:... I think therefore I am. III: ... the idea of an infinite and perfect God must have come from something outside me, so God must exist. IV: God is not deceiving me about the things of which I have clear and distinct perceptions. V: ...for example, mathematics... VI:...Using several senses together I can determine what is true. But we don't always have time for this, so we often make mistakes.

3. (end of Meditation One) “ I confess that there is nothing in all that I formerly believed, which I cannot doubt in some measure. We must be careful to keep this in mind, and fear not that there is peril or error in yielding to distrust, since I am not considering questions of action, but only of knowledge. So, I intend to attach myself to the idea that some evil genie is deceiving me; that the heavens, the earth, colours, figures, sound, even my body and senses are nought but illusions and dreams. This task is a difficult one, for just as a prisoner who dreams of liberty, when he begins to suspect that it is but a dream, fears to awaken, so I may fall back into my former opinions.”

4. Charles Sanders Peirce (1893-1914) thought the Cartesian method of doubt illegitimate: “ Let us not pretend to doubt in philosophy what we do not doubt in our hearts.” -Some Consequences of Four Incapacities

5. Similarly, George Santayana (1863-1952) found Descartes' willingness to entertain doubt towards concrete “external” realities literally incredible. Our actions constantly betray “a form of some faith in animal, material existence.” Scepticism is the chastity of the intellect, and it is shameful to surrender it too soon or to the first comer. quotes There is no dilemma in the choice between animal faith and reason, because reason is only a form of animal faith...

6. Descartes seems to argue in a circle ... “ Whatever I clearly and distinctly perceive is certain; this is true because God has given me these perceptions, and God is no demon or deceiver. How do I know that ? Because I have a clear and distinct perception of God as good. How do I know that God exists? Because my clear and distinct perception of God – the reliability of which God ensures - entails His existence...”

7. In other words.. .

10. "Cartesian dualism": mind and body are separate substances. "Distinguishing the mind and the body provided a realm for science, concerned with the physical world, to proceed unhampered by religion. ... and a realm for religion and human freedom that would not be threatened by science." (75)