Thursday, February 17, 2011

David Hume's "Sceptical Doubts concerning the Operations of the Understanding, and a Sceptical Solution": A Summary

We have two kinds of ideas: 'relations of ideas' and 'matters of fact'.

'Relations of ideas' are simple and provable without any recourse to experience at all - think math. Three times five will always be fifteen, and nothing can change that. These are absolutely certain. It would be a contradiction of logic if three times five equaled anything else. It's impossible.

'Matters of fact' not so much. Matters of fact require experience. There's no way you could reason your way to the sun rising, or even to the existence of the sun, without having some experience of the sun. There's nothing in logic or mathematics that says that the sun has to come up or that your friend is too hammered to walk - you couldn't prove or disprove either of them. Of course, we don't directly experience everything we think we know - in fact, I'll bet you think you know a lot of shit about tomorrow that you couldn't possibly have experienced.




'Yeah, the sun will definitely rise tomorrow.' Really? Are you sure? How could you possibly know that? Logic doesn't demand a rising sun. Sure, physicists says the sun should rise tomorrow, and they have a lot of numbers and math to back their shit up. But how do you think they got those numbers? After all, Aristotle thought we were at the center of the universe, and Copernicus thought the sun was at the center of the universe but his system didn't work at all. It's not like Newton sat down and said, "I wonder how gravity logically has to function." There would be no contradiction if gravity were half as strong as it is - the universe would just look a little different. Newton just dropped a lot of shit over and over again to see how long it took to fall and then worked backwards from there. He observed.


What if I hit one billiard ball with another - will the second one move? You keep saying yes, but there's no way to prove it. Cause and effect? Look at this billiard ball - look real fucking close. Now tell me: how the fuck do you know from looking at this that it has the property 'Will cause another billiard ball to move if struck'? Am I missing something here? Because I don't see anything in this ball that makes it a necessary cause of something.


Everything you think you know about cause and effect, about the future itself, is based on the assumption that everything in the future will always work the way it has worked in the past, and there's no way to prove that. You definitely can't prove it using logic - there's no contradiction in the idea. Maybe the future won't resemble the past. Problem? You also can't prove it using observation, since that's what we're already talking about. "Well, so far the future has resembled the past - it has always been the same." That doesn't matter. It's circular to say that because everything has been the same, everything will be the same. Unless you've observed the future yourself, or have some argument that I'm missing, there's no way you could possibly know any of the things you're so sure about. There's no justification for that knowledge.


Well that was fun, wasn't it? But look, that doesn't mean you should throw out everything you've ever thought about cause and effect - after all, acting like it's a real thing has served you well so far. So here's where we're at - you're in a bar with your bros, pounding some brewskis, when some asshole hits the cue ball wrong and the 8-ball comes flying at your head. What do you do? Do you think "You know, there's no way I can know for sure that the 8-ball could cause my skull to fucking fracture. After all, I can't know anything about the future"? No. You don't even think, "That ball has causal powers which, if it strikes me, will have the effect of great pain. I should move." You get the hell out of the way, and after the ball whizzes past you you make sure that dickhead knows he better watch out next time. Why do you get out of the way? Because you have formed a belief about cause and effect, because you've seen it so many times. What if you put some guy with no experiences in that spot? Does he move? No, he watches the ball all the way to unconsciousness; he doesn't know any better. I know that because I did it when I was six, and so did you - when you were a kid with no experiences, playing catch with your father or whatever, you got hit in the head, cried your eyes out, put ice on it, and thought, "So, apparently getting hit in the head with shit causes pain. Fucking got it." It's not because you observed something in the ball that causes pain, but because getting hit in the head is always conjoined to pain. They go hand in hand. They're always together. When one billiard ball hits another, the other one has always moved. So when you see one about to hit another, you think "Okay, I've seen this before. After that one hits, the other one moves. It just always happens that way." And if it didn't happen that way, you would be disappointed and surprised  - not because of any reasoning you carried out, just because that's not what you expected. 


If the sun didn't rise tomorrow, that wouldn't be a contradiction, but it would surprise the fuck out of you. The morning and the sunrise are constantly conjoined. It's that simple.


Fun fact: the mind works the same way. When you will your arm to move, it moves - how the fuck does that happen? There's no contradiction in your arm not moving; nothing says your arm has to move when you will it to move. I will myself to fly, but that doesn't quite work, does it? Watch a baby learn that his hands open and close when he wants them to - it's cute as fuck, because the baby is just so goddamn surprised. If babies could talk he'd say, "Look at the control I have! I can control these things with my mind! I AM LIKE A TINY GOD." When you get the feeling that you're going to puke, you don't waste time reasoning your way to puke, you get to a bathroom, because hangovers and puking have always gone hand-in-hand, and you don't believe this will be any different.


And it turns out, it's a good fucking thing that cause and effect are instinctive responses and not reasoned knowledge, because reason is so very fallible, and we know so very little. The ancients believed crazy shit about how things moved - Zeno thought he'd proven that a billiard ball flying at his head should never reach him, because it always has to cover half the remaining distance to his head. But if you threw a ball at him, you bet your sweet ass he'd move rather than standing there all smug and thinking, "Heh. It'll never get to me. Way too far to travel." Instincts and beliefs keep us alive and help us function - if knowledge was all we had to go on, we'd be in deep shit indeed.


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If you want to read the original, Sceptical Doubts and Sceptical Solution are sections four and five of David Hume's Enquiry.



8 comments:

  1. Awesome.

    (Now I want to read your summary of Zeno!)

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  2. Nice explanation, but didn't Hume say that anything that doesn't fit into these two categories should be 'cast into the fire'?

    Edit: just found the quote.

    "If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion."
    - An Enquiry Concerning Human Understanding

    So you missed out the explanation of how Hume's philosophy was self-refuting. If we only accept as knowledge propositions that are tautologies or scientifically demonstrable then we are left with no founding principle grounding our knowledge.

    To put it bluntly, "Only propositions that are tautological or scientifically demonstrable can count as knowledge", what about that sentence itself? You definitely can't go out into the lab and prove that principle. But it also clearly isn't a tautology, otherwise it wouldn't be worth saying. So Hume's own principle cannot meet its own requirements.

    Not only that but according to this theory of knowledge doesn't ethics go out the window? And all metaphysics? And everything we know about causation? And all of political philosophy?

    So I don't know about you, but I think Hume was wrong on this one!! It ends up discarding most of what humans hold to be most important, whilst also being self-contradictory.

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  3. Michael -

    That's from section XII, I believe. Well outside the scope of this particular summary.

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  4. Hey Philosophy BrO, thanks for pointing that out, my bad.
    My criticism of it still stands though I guess :)

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  5. @Michael's argument

    I dont think Hume was only referring to facts that are scientifically demonstrable or tautological. I believe he simply means that in order for something to be true by something other than fact, it has to be related to EXPERIENCE. Experience in the living and literal sense. Think John Dewey.

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  6. If I pass my second-year philosophy exams, a lot of it will be down to you. Thank you

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  7. an interesting and helpful summary!

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