ScepticismScepticism'Some years ago I was struck by the large number of falsehoods that I had accepted as true in my childhood, and by the highly doubtful nature of the whole edifice that I had subsequently based on them. I realized that it was necessary, once in the course of my life, to demolish everything completely and start again right from the foundations ... ' Descartes, First Meditation, Reader, p.175.
Descartes starts off with the thought that beliefs derived directly from the senses would seem to be the ones we can be most sure of, eg 'that I am here, sitting by the fire, wearing a winter dressing-gown, holding this piece of paper in my hands, and so on.'Descartes, First Meditation, Reader, p.176.
Insane persons firmly maintain eg' that they are kings when they are paupers, or say that they are dressed in purple when they are naked, or that their heads are made of earthenware, or that they are pumpkins, or made of glass.' Descartes, First Meditation, Reader, p.176.
In our dreams we have all kinds of beliefs which we accept afterwards are mistaken.
In a similar way, painters composing fictitious scenes use elements that are real enough:' For even when painters try to create sirens or satyrs with the most extraordinary bodies, they simply jumble up the limbs of different animals. Or if perhaps they manage to think up something so new that nothing remotely similar has ever been seen before - something which is therefore completely factitious and unreal - at least the colours used in this composition must be real. By similar reasoning, although these general kinds of things - eyes, head, hands and so on - could be imaginary, it must at least be admitted that certain other even simpler and more universal things are real. These are as it were the real colours from which we form all the images of things, whether true or false, that occur in our thought.
This class appears to include corporeal nature in general, and its extension; the shape of extended things; the quantity, or size and number of these things; the place in which they exist, the time through which they may endure, and so on.' Descartes, First Meditation, Reader, p.176.
Descartes thinks that the laws of geometry and arithmetic hold in our dreams as well: "… [F]or whether I am awake or dreaming, it remains true that two and three make five, and that a square has but four sides; nor does it seem possible that truths so apparent can ever fall under a suspicion of falsity [or incertitude]. Descartes, First Meditation, Reader p.176,7.
Having presented this thought, D proceeds to demolish it.
'One reason is that people have made mistakes in reasoning in such matters, and have held as certain and self-evident what we see to be false.'
'A more important reason [than the fact that we sometimes make mistakes in geometry and arithmetic] is that we have been told that God who created us can do all that he desires, and we do not yet know whether he may not have willed to create us in such a way that we shall always be deceived even in the things that we think ourselves to know best. (The Principles of Philosophy, Part I, Section 5, Cottingham edition, p.161.)
Descartes' invocation of a possible Evil Demon: 'I will suppose ... that ... some malicious demon of the utmost power and cunning has employed all his [sic] energies in order to deceive me. " Descartes, First Meditation, Reader, p.177.
VP