A transcript of Hume's convo in the "Great Philosophers" Chat Room
Hume123: Ah, 'tis a wonderful, sunny day. A fine day for enjoying the Company of good Friends, perhaps hoisting a few pints together. Tomorrow, I hear, will be sunny, too—assuming, that is, that the sun will rise at all.
Kant84: What do you mean "assuming that the sun will rise at all"? We don't have to "assume" that—we know that it will rise.
Hume123: Immanuel, is that you? Do you mind if I call you Manny? Manny, Manny, that the sun will rise tomorrow is a matter of fact, something we know only from experience. And that means there is no necessity whatsoever that this phenomenon will continue to occur, though of course we have the habit of believing that it will occur.
Kant84: What? What? You're crazy. The sun must rise tomorrow. It must. There is no alternative. There issssssssssssss
Hume123: Are you asleep? Wake up, Manny!
Descartes01: Oh, let the man sleep. He probably had a long night. Besides, how do we know we're not the ones who are asleep right now and dreaming all of this?
Hume123: I'm skeptical, but I'm not that skeptical. I know I'm awake, anyway. In any case, that is no ordinary sleep that Kant has fallen into. That is a dogmatic slumber—I'm quite sure of it. He'll thank me one day for awakening him from this. Kant, wake up NOW.
Kant84: What? Oh, yes, yes. Thank you. Well, I don't think you're right in what you're saying, but it seems you've given me something to think about.
Anonymous: Any ladies here?
Anonymous: Any ladies here 2 chat?
Hume123: Ignore him; he'll go away.
AdamSmith76: Hey, buddy, did you happen to notice the name of this chat room? It's "Great Philosophers." I don't know exactly how to express this point to you delicately, but this is probably not the optimal place to find members of the opposite sex.
AlexanderPope25: Is that you, Descartes? You don't have to hide behind that "anonymous" name—we all know what you're about.
Descartes01: A false and completely refutable accusation. Mr. Anonymous is not me. I am right here, of that I am utterly certain. Of course, by "I," it is not meant my body, but only my mind.
Hume123: Wait a second, you doubt everything else, but you're absolutely certain that you as a mind, as a thinking substance, exist?
Hume123: Have you ever actually observed this mind you are so sure exists? If so, produce the impression.
Descartes01: Easy. I now have an impression of red, of that I have no doubt. And if I sharply bring this hammer down on my finger, I will have an impression of pain.
Hume123: Well, with that last example you are simply speaking from past experience. You don't know that the future will resemble the past.
Descartes01: Oh, yeah? Watch me prove it. I'll take this hammer and… ahhhhhh! Now look at what you've made me do. I can barely type.
Hume123: Sorry, that was just a little joke on my part. LOL. It's amazing how many people fall for that one! Though that business about the future not necessarily resembling the past is true, that's not actually my point here. My point is that all you've done by bringing up your perception of redness and pain is give examples of particular impressions. But that's not what I was asking for. I was asking for an impression of the mind itself, of the supposed underlying substance in which these various impressions dwell. For all we know, these perceptions can exist on their own. Have you ever actually directly experienced this mind, this elusive self?
Descartes01: Well, that's a difficult question. I am quite certain I could answer it if—
Hume123: You keep meditating on that, René. It will take you a while. For I insist that no one ever does experience such a thing. That's right, I'm saying there is no self! Yes, you heard me. I say that we are nothing but a bundle of individual, discrete perceptions.
Rousseau99: I found you, Hume! You thought you could hide from me, did you? You thought you could conceal your evil plot against me? You have no idea who you're up against.
AdamSmith76: Do not speak to David that way—he is a good man, through and through. What on earth are you going on about?
Rousseau99: He lies! He lies! Don't be taken in by the genial exterior. The man is a viper, a killer. And he's not the only one—he's the leader of a whole group, a group that spans the entire world. They're all out to get me!
AdamSmith76: How dare you—
Hume123: It's okay, Adam. Jean-Jacques has just been having a, well, difficult time lately. He really is well intended at heart.
Descartes01: Wait a second. Now you've sort of got me intrigued with this argument against the self. It still sounds preposterous to me, though. Next thing, you'll be telling me there is no external world, either.
Hume123: I wouldn't say that. But I would say that the existence of the external world must remain forever in doubt.
Descartes01: LOL. Forgive me, young man, for laughing, but I used to believe the same thing. Let me walk you through the ringing disproof of your skepticism.
Hume123: Please do.
Descartes01: We'll leave aside this question about the supposed nonexistence of the self for the time being, okay? We don't need to worry about it for the present argument. It is enough that you admit that you have direct, immediate access to the contents of your mind—what you call ideas and impressions.
Hume123: Not only do I concede that point, I use it to make my own argument, as well.
Descartes01: Very good. So, right now, I undeniably have an impression of pain (my finger still hurts, thanks to your little joke). Now, ordinarily, I infer from that impression that there is something outside of my mind that caused that pain, in this case a hammer. But I realize I could be wrong there—maybe it wasn't a hammer, maybe it was some unknown part of my mind that was the cause. Or maybe the pain came directly from God. Any of these three possibilities could have been the cause—I have no way of deciding between them. And yet still I strongly believe that the sensation of pain comes from a hammer.
Hume123: I confess to the same belief.
Descartes01: But then look at what you're committed to if you deny that something like a hammer exists outside of yourself. You're saying God has set things up in such a way that we have no way of knowing for sure whether or not there are things outside of us, yet we also have a strong tendency to believe this is the case. If it turned out we were then wrong in that belief, then this would show that God is a great deceiver, that he is intentionally misleading us. You can't have that, can you?
Hume123: Well, whether God could be a deceiver or not is not my concern. My question is: how do you know that God exists in the first place?
Descartes01: How do I know? Why, I've proved it definitively, young man, through two different a priori arguments—arguments that rely on logic alone!
Hume123: A priori arguments, huh? Well, as I convincingly show in my Dialogues Concerning Natural Religion, all a priori arguments for God's existence are destined to fail. After all, if a claim can be established a priori, its opposite must be inconceivable. I can prove that 2+2=4, because to imagine 2+2 not equaling 4 is impossible. But there is nothing inconceivable about the possibility of God not existing. Whether God exists or not is simply a matter of fact. And the only way to establish any matter of fact is through experience. Sorry, but using logic alone is just not going to cut it in this case.
Descartes01: But, but…
Hume123: And now look what happens to your argument. Without bringing God into the debate, we are left in the doubtful situation you were just describing: it turns out we have no way to establish the existence of the external world. My impressions exist, yes, but I cannot be certain that there are external objects that correspond to them, or, if there are external objects, what their real nature might be. We must remain skeptical about this most basic fact, no matter how unsatisfying that may seem.
Descartes01: But I don't want to believe this! My will is absolutely free, after all—I can believe whatever I want.
Hume123: Ah, yes, free will. You may not be surprised to learn that I have dealt with that issue as well in my writings. In my Enquiry Concerning Human Understanding, for example, I show that the whole free will/determinism debate is a mere verbal dispute, an argument over terms. Once we become clear about what we mean by the words "free will" and "determinism," we realize that we have free will in one sense and are determined in another sense. And, what's more, everyone actually agrees on this point—once they clearly understand the terms involved. Shall I demonstrate?
Hume123: Hmm, he seems to have left the chat room. I seem to have that effect on people for some reason. Does anyone else want to debate me?
Rousseau99: I'll debate you, you swine! I'll expose you for the—
Hume123: I mean anyone other than Jean-Jacques. Anyone? Well, I think that sound of crickets must mean it's time for me to get off the internet and go outside.
Anonymous: Any ladies here?