Hume on Causation & the Problem of Induction (John Searle)

anyway let's go on now we're going to talk about causation just as when you talk about the mind you have to talk about Descartes when you talk about causation you have to talk about Hume and Hume is the decisive author on the subject of causation and in fact if it's true that Kant is the greatest philosopher that ever lived I don't know if it is true but certainly it's it's arguable Khan himself says that it was reading Hume on causation that woke him from his dogmatic slumbers he thought whatever else he does he's got to answer Hume on this skepticism about causation so here we go question one why is causation such a big deal why is it so important and Hume says all of our knowledge about reality that goes beyond our immediate experiences relies on causation so if I believe that I'm seeing a hat well that's my immediate experience but if I believe that this hat is the same hat as the Hat that I wore yesterday then that relies on causation because I must assume that the object that I see in front of me is causally continuous with an object that existed in the past and similarly with any general belief if I believe that the Sun rises in the east or that bodies attract according to Newton's law of gravity all of those presuppose the notion of causation they presuppose a causal regularity in the universe and science consists in discovering these causal regularities well in says Hume it's very important that we become clear about the notion of causation what are the components of our reasoning about causation and nowadays we would put that question by saying what's the definition of causation and um says there are three parts to the definition causes must be prior to the effects prior in time I can't do something now that will make something happen differently yesterday from the way that it did happen the Republicans can't now think well let's fix things up so that Obama didn't win the election so that McCain won the election too late I mean you can't make causes go backwards sometimes you can have simultaneity you can have the cause and effect simultaneous with each other I mean the last car on the train is caused in its movement signed by the simultaneous movement of the engine of the train but you cannot have the the effect occurring before the cause secondly you have to have contiguity in space and time if I now sneeze and the Eiffel Tower in Paris falls over then my sneezing can't cause the falling of the Eiffel Tower unless there is some causal chain connecting my sneezing to the Eiffel Tower you can't and not this was some nice but by saying you can't have causation at a distance the cause and the effect have to be next to each other in space and time let's assume novice ly that's not enough just having one event before another event and and they occurred next to each other that won't give you causation you've got to have something in addition to that and Hume says there's got to be a connection there has to be a necessary connection between the thing we call the cause and the thing we call the effect and there are various ways of putting that we say the cause makes the effect happen or the cause produces the effect or the cause is a force that generates the effect all of these are driving at the same thing they're driving at the idea that there must be a link there must be some sort of link between the cause and the effect and now comes Humes first great sceptical conclusion there is no such thing as necessary connection in nature if you try to look for a necessary connection you can't find it no white sail but they look at our necessary connections everywhere if I turn this switch the light goes off if I turn it again it goes back on again I mean that stuff there you've got it necessary connection and um says look carefully what you saw was event a I flipped the switch and that's followed by event B the light went on there is no necessary connection now somebody who knows about electricity will say yes well there is a necessary connection because the passage of the let's suppose it's a conventional electric light the passage of the electrical current through the tungsten filament will activate the molecules in the tungsten in such a way that it exhibits light that it gives off light waves but human would say what you've done is just identify another event see between a this is switch and this is light and this is activation of the tungsten filaments but that doesn't get you out of the problem because now you need a necessary connection between a and C and C and B and even if you could find those that would just give you D and E and then you'd need a necessary connection a and D D and C C and E and again B there is no necessary connection in nature all you find is a sequence of events you do not perceive a necessary connection now Hugh makes it look as if well that's just a kind of odd fact about our experiences but it's clear to me that he thinks it's impossible that there should be a perception of necessary connection it isn't just that we don't happen to find it as I don't happen to any live rabbits I in this cabinet here nope no live rabbits in there I he makes it talk as if what we just didn't find it isn't that too bad but it's clear nothing would count as a necessary connection however Hume is obviously enjoying himself immensely and as I said this is probably the best English philosophical prose ever written as human a book one part three of his famous treatise and he says well let's beat about the bush and see if we can't find a necessary connection we'll just sort of look around the neighboring fields and see maybe there's a necessary connection lurking somewhere and then he says well there are two principles that we need to examine concerning our reasoning concerning cause and effect and these are the principles that every event has a cause and like causes have like effects and these are every e has C every man has a cause and like these have like let's put it the other way that's what like causes have like effects like C's have like ease in other words any event that occurs has a cause and similar causes produce similar effects and Hume says those are essential to our reasoning concerning cause and effect and I think he's right about that is that we do accept those in our ordinary reasoning if you're a graduate student in the history department and you decide you want to do a study of the causes of the Vietnam War and you investigate it and then you say well you know the Vietnam War it's one of those funny things didn't have any causes there were no causes to the Vietnam War you will not get a PhD in the history department is not going to make it we assume that events have causal explanations furthermore with some regularity if somebody says well the thing about disease is I'm a particular disease let's say AIDS a that it can be caused by all kinds of things but there's no regularity I to that cause in effect it's just one damn thing after another we won't accept either we assume that there is a regular structure to the universe and that regular structure is determined by causal regularities Hume calls this the principle of causation that every event has an effect and this is the principle of causality okay now then the crucial question becomes how do we know that these are true how do we know that every event has a cause and like causes have like effects what's the evidence and now comes his second great sceptical conclusion the first was there are no necessary connections thus get the second great sceptical conclusion is there's no way you can establish these indeed you can't even get any evidence for these because any evidence presupposes these now that's his this has got a name this part of his argument it's called the problem of induction and Humes skepticism about induction is one of the most famous skeptical arguments in philosophy and I'm now going to explain it to you in some detail if you think of how we reason a typical pattern of reasoning is called deductive and in a deductive argument in in a form of deduction you have premises and the premises logically imply or logically entail the conclusion I'm embarrassed to give you these tired old cliched arguments but why not it's a familiar one and it goes Socrates is a man and all men are mortal then it follows you can conclude therefore Socrates is mortal I said I was embarrassed to give you a such a cliched example I'm always tempted to say well let's suppose Socrates is a marginal schizophrenic and all marginally schizophrenics suffer from left-handed athletes but you know I could do something I think but then that's distracting it's this right now you start thinking about athlete's foot ssandsk it's over the hell with it let's stick with a with a textbook example Socrates is a man all men are mortal so Socrates is mortal now says him in this case if these are true this must be true this is a valid argument because the truth of the premises is logically sufficient to guarantee the truth of the conclusion in the case of this you go from the premise to the conclusion where the premise is always greater than the conclusion in a limiting case you can have an identity Socrates is a man therefore Socrates is a man that's a valid argument just kind of boring because the premise and the conclusion are identical but in a valid deductive argument in the standard case like this there's more in the premise than there is in the conclusion the conclusion just makes explicit what's already implicit in the premise but now that's not how science works science works by discovering new knowledge not just by working out the logical consequences of old knowledge in the case of a scientific proof you go from evidence to hypothesis and in that case there's always more in the hypothesis than there is in the evidence now let's contrast these two in this case we went from premise to conclusion and how do we get away with it well we get away with it because there's more in the premise than there wasn't a conclusion the conclusion just spells out what's already implicit in the premise but in induction over here we go from evidence which supports the hypothesis i mean i we don't just say things like well bodies attract in our lab what are they doing your lab no we assume we're discovering something that's absolutely universal that there's a perfectly general claim that we can make on the basis of our crucial experiments so in this case we go from evidence which supports the hypothesis but the evidence is always less than the hypothesis the hypothesis always has more than is in the evidence and human puts this by saying we go from some to all we observe some cases like this so assume all case or like that or we assume that nature is uniform that if we conduct these experiments in our lab those experiments will be replicable if they're not replicable then there was something wrong if you can't replicate the experiments so we assume the future will resemble the past unobserved instances will resemble observed instances nature is uniform I assume says those are all different ways of saying the same thing but now how does it work then if we go from the evidence to the hypothesis where the evidence is always less than the hypothesis well the answer we all suppose and Hume agrees is well it's not just random you don't just have any evidence supports any hypothesis but you follow the rules the rules of scientific method you follow a set of rules of scientific research called M R so on the basis of evidence given R you adopt a general hypothesis the AIDS is caused by the HIV virus or I attract according to the inverse-square law you have a universal conclusion based on a finite amount of evidence you go from sum to all from the finite to the infinite and you do that because you're following the rules of scientific method alright but now we can now focus what exactly is the status of our how do we justify our you see deduction by itself isn't going to get us anywhere because all we do is make explicit what's already implicit in what we already know but to get new knowledge we have to use induction we've got to from observed to the unobserved from the from the past and the present to the future from the finite to the infinite from some to all from the particular to the general but that can't be just random you can't just say anything there have to be some rules on the base of which you proceed what what are the rules and what's their status well says you I just told you the basic structure of the rules the rule is the assumption that the unobserved instances will be resemble the observed instances that the future will resemble the past that nature is uniform or the most simple way to put those two is simply to say every event has a cause and like causes have like effects those are the basic assumptions but now how do you establish those how do you establish that every event has a cause and the light causes have like effects you can't say well we go from E to H where H equals R so we go from just from E to R we go from evidence to the assumption that nature is to establish the assumption that nature is uniform because we saw up here that this type of argument only works if presuppose R and that means it's circular you got R on both sides does everybody see that now this is Humes second most famous skeptical conclusion the first one was there are no necessary connections in nature the second one is the induction is not a justified form of reasoning because any effort to justify induction presupposes induction any effort to prove that nature's uniform that the future will resemble the past that the unobserved will resemble the observed all of those presuppose what they're trying to prove all of those arguments are circular you all believe that if I drop this it will fall to the ground what's your evidence it turns out your evidence is about something irrelevant it's about passed and you might say no no we know a law I know the high the inverse-square law bodies attract with a force inversely proportional distance between them and directly portion the product of the mass I had to memorize that in high school and I God knows what they do now in high school I don't know if you've memorized anything in high school but I did memorize the inverse square law okay but that's no good because humans would say and how do you know that that law is true because all your evidence is about the past see you do suppose that if I drop it it will fall but you never really know if I don't drop it you'll never know what would have happened if I had let go of it it's true you have this deep superstitions I'm going to tell you about those in a minute but it's just a superstition there's no rational ground for supposing it will fall now this is Humes most spectacular conclusion he's not saying look you don't have enough evidence that if I release it it'll fall humans saying you have no evidence you have zero evidence occurs near evidence about something else it's about what happened last night or yesterday or last year or sometime in the past and we're not talking about we're talking about the future and our question is will the future will resemble the past and about that you have zero evidence nothing you have no evidence at all because remember this evidence only counts as evidence for H given R and you have no evidence for R and you couldn't any attempt to give it evidence for R will be circular it will beg the question okay so we got two spectacular results there are no there's no glue that holds the universe together no necessary connection and all in forms of inductive reasoning all forms of scientific reasoning are invalid they're all based on a kind of blind faith we can't help having this stupid faith he was going to tell you why we have it these are the problem of causation and the problem of induction in Hume and the skepticism about causation is there isn't any necessary connection in nature and skepticism about induction his induction is an invalid and unjustified form of reasoning if we believe in induction is just blind brute animal faith with no rational ground whatever you might have loved Darwin huh because Darwin is saying what looks like an order in nature is just the result of natural forces humans going to explain the natural forces that that I force us to believe stupidly that if I let go of this it will fall to the ground yeah we have zero evidence that it will but that's what we believe now when I first read this stuff I was a 17 year old freshman and I thought well I don't answer that on this human was right but here was my mistaken answer I thought look it isn't justice that I believe that the future will resemble in the past future resembles the past because of course I have a lot of evidence that the future will resemble the past because what we now think of as the past contained a lot of parts that were once future right day before yesterday yesterday was the future right okay but in the past the future did resemble the past right because day before yesterday did resemble yesterday and two weeks ago resembled a week ago and three years ago resembled two years ago so I had a lot of hard solid evidence that the future resembles the past because past futures have resembled past pasts so everybody get my argument it's a bad argument Hume would say that's all irrelevant because we're not talking about pass pass and past futures we're down by the future and the past and the fact that in the past past passive resemble past futures is simply irrelevant to the question whether or not the future where we resemble pass futures and pass pass and pass future pass and all the rest of it all of that is beside the point does everybody see Humes answer to me oh well they're not bad for a 17 year old kid anyway so we've still we've got this problem okay now Humes method in philosophy is to give you a whole lot of skeptical results and then show you why you can't help believing all the superstitions that you do in fact believe you believe you're the same person as a person that was here last week no evidence for that whatever you couldn't have any you believe that this is a material object that will continue to exist when no one is looking at it you know evidence for that you also believe that nature is uniform and that science is reliable I'm going to explain to you that you have no evidence for that but I'm going to tell you why you can't help having all these beliefs and I'm now going to tell you why you believe in induction even though induction is an invalid method of reasoning he said we when we went to look around the bush to try to find the components of our reasoning concerning cause and effect incidentally Hume writes a beautiful prose and I'm sorry we can't write that way any more long mellifluous sentences with many relative clauses and a free use of the subjunctive God how I miss the subjunctive is dying in all languages like it there are expressions in English like far be it from me that be is a shopping far be it for me to use the subjunctive in a lecture but anyway I just did so the subjunctive appear even in French its dying I hated it when I first learned French but now I'm kind of missing a focus you Mon I now people say door mentality which seems to me kind of I won't say bad words about it but it seems kind of cowardly not to use the subjunctive but in any case him I uses this wonderful prose and he does say that he's going to explain to us our component reasoning concerning cause-and-effect and it's true we didn't find necessary connection but we found something else we found a constant conjunction of resembling instances so it's true when I release the piece of chalk there's absolutely no necessary connection between my releasing and the chalk falling to the ground there is no causal connection in nature however there's an odd thing about our experiences namely whenever we observe the thing we call the cause it's always conjoined with it's always followed by the thing we call the effect so what causation amounts to is not priority contiguity and constant unnecessary connection but rather priority contiguity and a constant conjunction of resembling instances well wow how did we ever get the idea that there was such a thing as necessary connection Hume says because of the constant repetition of the continued examples you get a kind of felt expectation your mind develops a kind of habit of expectation so if I say to you I'm gonna release this piece of chalk you will expect it to fall to the ground and not float up to the ceiling I turn into a flower or explode in my hand you will have an expectation now this felt determination of the mind to pass from the perception of the cause to the idea of the effect or if you like just from the idea of the cause just imagine that I'm releasing this from the idea that cause to the idea of the effect the felt determination of the mind is where we got the idea of necessary connection we thought that because it's in our mind it must be in the real world in our mind there is a felt determination to pass from the perception or idea of the cause to the idea of the effect we form as Hume says a more lively idea of the effect but the felt determination of the mind gives the illusion of necessary connection now I think most philosophers today would reject Humes problem of induction but they and and Humes but they accept his analysis of causation and they think really the fact that makes causal statements true is not a fact about the particular example but a fact about the universal laws that describe how nature works so the picture that survives in Hume to the present day and most philosophers accept this is that it's true humans right we can answer him on induction I'll tell you about that on Thursday but but I they that the the thing that he's right about is the idea that there is no causal glue that holds the world together the world is held together just by regularities and what we think of as causal connections are just instances of universal regularities so for every causal statement of the form a crosby there must be some universal law that says events of the eighth type are invariably followed by events of the beat type ok so here's where we are there is a tremendously powerful skeptical argument against the idea that nature is held together by necessary connections by kind of causal glue and there is an analysis of induction to show that induction is inherently unjustified and irrational any attempt to justify it would be circular and there's a positive account that says we get the illusion of a regularity and uniformity of nature simply because the constant injunction of resembling instances creates a kind of habit in us a habit of expecting that things will go on in the same way

Channel: Philosophy Overdose

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Keywords: Philosophy, David Hume, Hume, Epistemology, Problem of Induction, Scepticism, John Searle, Causation, Metaphysics, Skepticism, Empiricism, Constant Conjunction, Induction, Analytic Philosophy, History of Philosophy, Necessary Connection, Metaphysics of Causation, Causality, Nature of Causation, Knowledge, Inductive

Id: BqVUKmUlF7E

Length: 28min 55sec (1735 seconds)

Published: Thu Mar 01 2018