I would like to borrow his idea of imagining there is a daemon trying to confuse and deceive us. Can we then allow ourselves to be certain about things like the existence of atoms? No, clearly not. What about the laptop in front of me? No, that is just as unsure. However, there seems to be a laptop in front of me. More accurately I can say that I experience a pattern of white and black patches of light. I dont see any way I can doubt that I experience this. For sure there may be no laptop, the demon may make me see white and black patches where I “should” see orange and purple, or the shapes may be changed. But stubbornly no matter how much I doubt the experience I am having the raw fact of its appearance cannot be doubted. Perceptions themselves, my experiences cannot be doubted.2 So I'd like to take as the raw atoms of truth not thoughts but perceptions, the totality of all I experience right this instant. 3 Descartes argues that the demon cannot deceive me unless there is a me to deceive, to me this rests too much on language to be quite convincing, I would prefer to argue that the demon cannot convince us that we are experiencing something that we are not, because in order to trick us, he would have to make us experience the thing.
This nugget of sure and certain existence is quite large, so I'd like to take a while talking about all the things I perceive. There are certain intuitions I have about my perceptions. The first an most important is the internal/external distinction. I perceive some shapes that I think of as being external objects and some that I think of as imagined objects. I perceive some sounds as being external things, some of being songs stuck in my head, and some (in the form of sounds identical to my spoken voice) that I regard as being my thoughts. For everything I think of as a sense there are imagined forms of them. However, there are other internal perceptions. Some imagined shapes that I “see” are identified as being “memories”, some imaginations of the future, some are imaginations of fantastic things.
The senses give us a lot of data to work with about this instant in "external" terms. But there a far greater depth in the "internal". I experience thoughts, emotions etc in a spectrum, going from the very concrete digital information of exactly reproducible "wordy" thoughts, to clear and sharp images, to fuzzy images, to fleeting impressions, to things just at the edge of awareness. There are many layers of internal thoughts and impressions just as there are many forms represented in many senses in the external.
We can "know" in the classical sense of sure and certain knowledge everything up to here. Beyond this point there can be no certainty about anything, we should not expect any, for if we do, we will be disappointed. Note, I cant even have totally sure knowledge of this kind about logic and maths. The statement "the square on the hypotenuse of a Euclidean right triangle is equal to the sum of the squares on the other two sides" requires some steps of deduction to be accepted, it is at least conceivable that I could have made an error every time I have proved it. This is not a very serious concern and one I will deal with later in its proper place, but it is enough for me to banish logic from the foundation and restrict it to the next few levels of deduction.
- Can anyone think of a way that this foundation can be doubted?
- Is it possible for me to doubt some of my perceptions?
- Are there any things that I can also believe in with total certainty.
1I'm a mathematician, I think philosophy should be as deductive as possible, so sue me.
2This “argument from brute force of experience” is hardly stated here in a logically rigorous way, but I dont see any way to doubt it short of total insanity, so I'm going to accept it.
3Note I cant quite argue that “I“ exist. Descartes and many since regard it as obvious that because we say “I think” or “I perceive” that there must be an "I" to do it. This doesn't automatically follow, at least, it does not logically imply that the perceiver and the perception are real distinct entities. I will however talk about I, because it's grammatically much less cumbersome, however this "I" is a rather ill-defined idea, so I'll try not to argue about it.