Meditations on First Philosophy, decoded


I’m retired. Now that I have the time, I think I should get rid of all my false beliefs and start building my knowledge up from a certain foundation. What else do I have to do today? Why not reinvent all of science?

Descartes' Bones: A Skeletal History of the Conflict Between Faith and Reason
A surprisingly fun book about Descartes. Recommended.

I won’t agree to anything that is probably or almost certain any more than I would agree to something obviously false. If I can doubt a fact at all, I’ll reject it. I will not deal with every belief individually, however. Instead, I will remove the foundations of my beliefs and knock all my shaky ideas down at once. This is the easiest way. For instance, I used to think that I could find truth from the senses. But senses often mislead us. We should not trust them to give us truth.

Some people say, though, that there are experiences we cannot doubt. Like, say, that I am here, by the fire, and holding a piece of paper. I’d have to be crazy to doubt that! That does seem plausible. The trouble is this: I sleep. I have even dreamed that I have been sitting, by the fire, holding a piece of paper, when I was actually in bed, asleep. Dreams can seem real.

Well, let me try that on for a second. What if I am dreaming? When I dream, I don’t dream anything new. I may dream that I have two heads, but I knew what heads were before I fell asleep. Painters imagine in the same way; they combine old parts to make new monsters. Even if you don’t believe that, colours are certain, and nobody can invent a new colour. There are many fundamental things like these: simple, universal things, and all the things in our consciousness are formed of those things. Maybe I can be certain about these things.

Extension, shape, number, place, time: these are all things that I know for sure exist, because everything else I see conforms to these things. Everything I know takes up space, has a shape, and is separated from other things. These qualities may be certain. If so physics, astronomy and medicine are all doubtful because they deal with physical things. Math and geometry deal with the pure things that everything has: extension and number.

Math and geometry would be more certain, unless even the most basic things, like numbers and space, cannot be trusted. God could have made them seem real all this time. He could have been fooling me. It would take a superhuman power to fool me about numbers, but God has superhuman powers.

Oh no. Everything can be doubted. I can doubt everything. I will not be fooled again.

Okay, it’s not God who would fool me, since you could excommunicate me like you did Galileo a couple of years ago. It’s an evil demon. An evil demon could be fooling me, making me think that 2+2=4, when in fact 2+2=5. Now all I know is that I can’t be sure of anything. Since I can’t be sure of anything, I will suspend judgment on everything.

This is making me tired. I’m going to bed.


I’m bummed out about yesterday. I’m going to stick to it though, and get rid of every belief that I can doubt at all. If any belief could be wrong, then it is as good as totally wrong to me. I’ll get rid of every belief until I find one I know to be true.

Everything I see seems to be doubtable. Everything I remember seems to be doubtable too. Everything I sense and the world outside my mind seems doubtable. Maybe nothing is certain.

Descartes: A Very Short Introduction
You owe it to yourself to read a real book of philosophy instead of this crap.

Maybe there is a god or something that makes me think these things. Or maybe there is not, since I could think them without help. Either way, though, am I at least not something? Before, I thought that there was no world outside of my mind. But did I think that I didn’t exist? No. Even if someone is always fooling me, I know that there is an I that is being fooled.

That’s it! This sentence, “I am, I exist”, is necessarily true each time it is expressed by me, or conceived in my mind! I think, therefore I am! Ego cogito, ergo sum! Je pense donc je suis!

Hold on: I don’t know what I am. I exist, but what am I? I need to be careful not to jump to conclusions.

There’s a lot I know I’m not. I may not have a body. I may not be a man. I may not have a soul.

I do know that I am a thinking thing. That much is certain.

Thinking is an attribute I certainly have. As long as I am thinking, I know that I exist. I am—I exist: that is certain. But if I stop thinking, who knows? I could stop existing. I am, then, precisely speaking, only a thinking thing. Still, that’s something: a thinking thing is a real thing.

Can I be sure of anything else? Not yet. What, then, am I? What is a thinking thing? It is a thing that doubts, understands, conceives, affirms, denies, wills, refuses, imagines and perceives.

I doubt, I understand and I desire. I also imagine, even though what I imagine may not be real. Even if what I perceive, see, hear, and feel is not real, I am real. All this perceiving is a part of thinking. I now know that I exist as long as I perceive.

It seems crazy to say that I can’t trust the external world, but that is the truth. I find it really hard to get my head around the idea that physical things can’t be trusted. Look at this piece of wax, though. It smells nice; it is cold and solid. It is as real as anything I can imagine. Yet if I put it near the fire, everything changes. It does not smell, look, or feel the same. It still seems to be the same wax—but every quality it had has changed. The external world is much more complicated than it appears. What is wax? Wax is like every physical thing. It is extended, flexible, and movable. Its other qualities are much less certain, but these qualities seem fairly clear. If we ignore the senses when we consider physical things, we can really get to the truth of what they are. We can do this with intuition and inspection of the mind.

Instead of abstracting from things we sense, we should build up from our innate ideas. Some ideas can be very clear and distinct. I have to be really careful. I’m very used to saying that I perceive things with my eyes. I don’t really. I judge with my mind and I see with my eyes. Often, I confuse these two things. It really seems like the clearest perceptions come from the mind, not the senses.

In conclusion, then, I do not know that I am anything other than mind. Whether I perceive with my senses or through introspection, I know, however, that I am. It is more accurate to perceive physical things with the mind than with the senses. My mind is the clearest thing my mind can perceive. I’m pretty dumb, so I’d better stick with this much for today.

Back to bed.