1. © Michael Lacewing Doubt in Descartes’ Meditations Michael Lacewing enquiries@alevelphilosophy.co.uk

2. Into doubt We can be deceived by our senses.

3. Into doubt (2) There are ‘no certain indications by which we may clearly distinguish wakefulness from sleep’.

4. The cogito I am certain that I think, I exist. I am a thinking thing. But I am not certain I have a body. = ?

5. 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.

6. 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.

7. 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.