Doubt in Descartes’ Meditations Michael Lacewing firstname.lastname@example.org © Michael Lacewing Into doubt • We can be deceived by our senses. Into doubt (2) • There are ‘no certain indications by which we may clearly distinguish wakefulness from sleep’. The cogito • I am certain that I think, I exist. I am a thinking thing. But I am not certain I have a body. = ? The wax argument • At first, our idea of the wax is of something defined by its sensory properties. • But this is muddled: when I melt a piece of wax, it loses all of its original sensory qualities, yet I believe it is the same wax. • This shows our conception of material objects, when clear and distinct, is as changeable and extended. The external world: two steps to go • Meditation V: we can know that clear and distinct ideas are true; so material objects really are extended, if they exist at all. • Meditation VI: We have experiences of an external world, which must either be caused by a real external world or God. God is not a deceiver. Therefore material objects do exist. Clear and distinct ideas • On the cogito: ‘In this first item of knowledge there is simply a clear and distinct perception of what I am asserting’. While thinking it, I cannot doubt it. • In order to be certain of clear and distinct ideas while we are not considering them, we must first prove God exists.