# Yes, dammit, one CAN prove a fucking negative **URL:** \ **Category:** The BBQ Pit\ **Created:** [July 23, 2005, 9:08pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846 "2005-07-23T21:08:37Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![magellan01](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@magellan01](https://boards.straightdope.com/u/magellan01)\ **Post date:** [July 25, 2005, 3:27pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/41 "2005-07-25T15:27:52Z")
> [@Liberal](#): > > Every negative is a contradiction of its positive; but likewise, every positive is a contradiction of its negative. (A And Not A) is a contradiction. Contradictions are the opposites of tautologies. Contradictions prove everything; and everything proves tautologies. Negation is nothing more than the application of a logical rule to a wiff (well formed formula). You can negate a wiff just as you can modalize it. All these assertions are equally provable (or not): > > 1. A — A is true > > 2. Not A — A is not true > > 3. A — A is necessarily true > > So what? Impossibility is merely the negation of modal necessity. > > 1. ~A — It is not possible that A is true (~ = ~\<\>) > > 2. ~A — It is possible that A is not true (~ = \<\>~) > > Nothing can be proved true by empirical observation. Empiricism can only prove things false. That is not a contingency of negation, but of the epistemic nature of empiricism. I’m not sure I follow you. Are you saying that these two statements are similar in form? A) There are no elks in my kitchen. B) Day does not equal night. While both can be proved (assuming one has access to one’s kitchen. it seems that the first one is subject to verifiability and falsification, the other needs no verifiability (checking), because it merrely involves contradicting the very definition of the entities (day, night) involved. Also, what about the question of Mr. Carriers boxes that I raised. Do you think that an infinite amount of time is adequate to investigate an infinite number of boxes? ---
**Author:** ![Liberal](https://avatars.discourse-cdn.com/v4/letter/l/848f3c/32.png) [@Liberal](https://boards.straightdope.com/u/Liberal)\ **Post date:** [July 25, 2005, 4:31pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/42 "2005-07-25T16:31:18Z")
> [@Finagle](#): > > Huh? That seems equally as silly as the assertion you’re ranting about in the OP. Can you explain in more detail why you feel nothing can be proved true by empirical observation? Especially given your prior conclusion that there’s nothing fundamentally different between logically proving an assertion and the complement of the assertion? Empirical observation (or more simply, science) relies on the philosophical principle of falsification. Falsification is what differentiates a science from a pseudoscience. (See [this exerpt](http://www.stephenjaygould.org/ctrl/popper_falsification.html) from Karl Popper’s _Conjectures and Refutations_.) When you make an observation, you merely confim that what you had believed (an hypothesis, for example) is either false or not false. Science is not a bivalent logical system (i.e., having truth values of only true and false.) For example, Newton’s laws are not false (because they do apply to certain reference frames), but they are not true either (because they do NOT apply to certain other reference frames). Here’s another way to think of it. If empricism did indeed supply truth, then it would be unnecessary ever to experiment further once an hypothesis is confirmed. After all, the truth has been found. > [@](#): > > Disregarding the scope argument, there is another class of argument for which no negative can be proven and which I think that the “Can not prove a negative” argument was originally concocted. You can pretty much never prove a negative in matters of faith, definition, (or imagination) because there are no falsifiable assertions. You cannot, for example, prove the negative of the statement, “I have a soul in my pocket.” Because even if I turn out my pocket, the definition of “soul” is untestable – it’s invisible, massless and has no detectable properties. Yet many people will swear to its existence. I think that there’s a bit of equivocation and amphiboly in that. For one thing, science does not test definitions, and definitions are not falsifiable. Science tests hypotheses, and it is hypotheses that are falsifiable. For example, if you were to test F=MA, you would not be testing the definition of force, but whether the amount of force you had hypothesized is indeed equal to mass times acceleration. This is an important distinction because definitions of words are language dependent and arbitrary, and sometimes even change over time. But the mathematical equivalency itself transcends such barriers and contingencies. > [@](#): > > How can I prove that a soul does not exist? Any property I assign to it will get defined away. Logic certainly isn’t going to help me here, because logic requires some testable predicates in order to be useful. Well, you can’t prove that a soul DOES exist either — especially not with empricism because, obviously, empiricism applies only to what can be sensed (or observed). I’ve never heard of the notion of a “testable predicate”, and I really don’t understand what it means. A logical assertion is true if it (1) follows from other logical assertions by the valid application of system rules, or (2) is accepted axiomatically. ---
**Author:** ![Liberal](https://avatars.discourse-cdn.com/v4/letter/l/848f3c/32.png) [@Liberal](https://boards.straightdope.com/u/Liberal)\ **Post date:** [July 25, 2005, 4:41pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/43 "2005-07-25T16:41:32Z")
> [@magellan01](#): > > I’m not sure I follow you. Are you saying that these two statements are similar in form? > > A) There are no elks in my kitchen. > B) Day does not equal night. A is a contingent proposition. B is a tautology. > [@](#): > > Also, what about the question of Mr. Carriers boxes that I raised. Do you think that an infinite amount of time is adequate to investigate an infinite number of boxes? I thought I covered that. Even if you have only one box, examining it will not prove any truth about its contents. Truth is an analytic thing; observation is a physical thing. ---
**Author:** ![I\_Love\_Me\_Vol.I](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/i_love_me_vol.i/32/521_2.png) [@I\_Love\_Me\_Vol.I](https://boards.straightdope.com/u/I_Love_Me_Vol.I)\ **Post date:** [July 25, 2005, 4:45pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/44 "2005-07-25T16:45:19Z")
Seems to me that you can prove a negative in a closed system (such as “this coin is not showing Heads”) but you can not prove a negative in an open system (“no green cats exist”, “planets are never made entirely of plastic”). ---
**Author:** ![magellan01](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@magellan01](https://boards.straightdope.com/u/magellan01)\ **Post date:** [July 25, 2005, 5:11pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/45 "2005-07-25T17:11:15Z")
> [@Liberal](#): > > A is a contingent proposition. B is a tautology. > > I thought I covered that. Even if you have only one box, examining it will not prove any truth about its contents. Truth is an analytic thing; observation is a physical thing. I’m really trying to understand this: “Even if you have only one box, examining it will not prove any truth about its contents.” So, does that mean that if you do examine the box and find whatever is in it–a marble, a giraffe, nothing–that your observation is worthless? That the box still may or may not contain what you observed? It seems you know a great deal more about formal logic than I, so please go slow. I find this extremely interesting and want to make sure I follow you. ---
**Author:** ![Liberal](https://avatars.discourse-cdn.com/v4/letter/l/848f3c/32.png) [@Liberal](https://boards.straightdope.com/u/Liberal)\ **Post date:** [July 25, 2005, 5:17pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/46 "2005-07-25T17:17:49Z")
> [@I Love Me](#): > > Seems to me that you can prove a negative in a closed system (such as “this coin is not showing Heads”) but you can not prove a negative in an open system (“no green cats exist”, “planets are never made entirely of plastic”). You can’t prove positives either in that circumstance. For example, Einstein’s second premise for special relativity is that physical laws are everywhere the same. It was offered as axiomatic precisely because it cannot be proved. ---
**Author:** ![Liberal](https://avatars.discourse-cdn.com/v4/letter/l/848f3c/32.png) [@Liberal](https://boards.straightdope.com/u/Liberal)\ **Post date:** [July 25, 2005, 5:28pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/47 "2005-07-25T17:28:27Z")
> [@magellan01](#): > > I’m really trying to understand this: “Even if you have only one box, examining it will not prove any truth about its contents.” So, does that mean that if you do examine the box and find whatever is in it–a marble, a giraffe, nothing–that your observation is worthless? That the box still may or may not contain what you observed? > > It seems you know a great deal more about formal logic than I, so please go slow. I find this extremely interesting and want to make sure I follow you. No, the observation isn’t worthless; it’s just a matter of proper context. Observations are very valuable for determining the statistical reliability of predictions. Making risky predictions (as you saw in the link provided) is what science is all about. The mistake is made when that statistical reliablity is extrapolated into analytical truth. In other words, the result of a scientific experiment (or observation) tells you _only about the particular hypothesis you tested_, and whether it was false or not _for that test_. Here’s another way to look at it. You can conduct experiments to convince yourself that 1 + 1 = 2 by examining objects and counting them. You will find that everytime you conduct your experiment, your hypothesis that there will be two objects will be confirmed. However — and this is a critical however — none of your experiments will tell you anything about the NEXT experiment. If you have tested it a bazillion times, you have not reliably proved that you will get two on the bazillion-and-first test. The only way to prove that 1 + 1 = 2 _necessarily_ is to use an analytic epistemology, like deduction. With the five Peano Axioms, the first inference you may draw is that 1 + 1 does indeed equal 2. But not only that, unlike with the scientific experiment, you have proved that 1 + 1 _will always equal two_ every time. ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [July 25, 2005, 6:10pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/48 "2005-07-25T18:10:47Z")
> [@Liberal](#): > > Empirical observation (or more simply, science) relies on the philosophical principle of falsification. Falsification is what differentiates a science from a pseudoscience. (See [this exerpt](http://www.stephenjaygould.org/ctrl/popper_falsification.html) from Karl Popper’s _Conjectures and Refutations_.) When you make an observation, you merely confim that what you had believed (an hypothesis, for example) is either false or not false. > : : : > > Here’s another way to think of it. If empricism did indeed supply truth, then it would be unnecessary ever to experiment further once an hypothesis is confirmed. After all, the truth has been found. Let’s be clear on a few things here. First of all, the statement that “Nothing can be proved true by empirical observation.” is just hilariously wrong (unless you want to get into the real navel-gazing philosophy that we can’t truly know anything). Even Karl Popper doesn’t say that. He’s talking about scientific theories and their relative worth. According to Popper, a theory that doesn’t produce risky hypotheses that can be proved false is worthless. However, “There’s no milk in the fridge.” is not a scientific theory. It’s a simple assertion of fact that can, in fact, be proved true by empirical observation. Second, just because Karl Popper says it, doesn’t make it so. You’re arguing from authority which is just another logical fallacy. > [@](#): > > I think that there’s a bit of equivocation and amphiboly in that. One would be tempted to think, here, that you are trying to intimidate with obscure words. Unless you can point out a grammatically ambiguous sentence in my post that changes its entire meaning? > [@](#): > > Well, you can’t prove that a soul DOES exist either — especially not with empricism because, obviously, empiricism applies only to what can be sensed (or observed). Well, I can’t right now prove that a soul exists, but it’s at least \* conceivable \*that someday one could, somehow, detect the presence of an intangible information-bearing component of an intelligent being that persists after its demise. However, by the way it’s defined, you could never prove that it doesn’t exist. > [@](#): > > I’ve never heard of the notion of a “testable predicate”, and I really don’t understand what it means. This is obvious to us all. BTW, I’m not convinced that Peano’s axioms buy you an increased belief in the truth of 1+1, given that they are, after all, axioms. ---
**Author:** ![Liberal](https://avatars.discourse-cdn.com/v4/letter/l/848f3c/32.png) [@Liberal](https://boards.straightdope.com/u/Liberal)\ **Post date:** [July 25, 2005, 6:53pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/49 "2005-07-25T18:53:11Z")
> [@Finagle](#): > > First of all, the statement that “Nothing can be proved true by empirical observation.” is just hilariously wrong (unless you want to get into the real navel-gazing philosophy that we can’t truly know anything). Even Karl Popper doesn’t say that. He’s talking about scientific theories and their relative worth. According to Popper, a theory that doesn’t produce risky hypotheses that can be proved false is worthless. That’s exactly what I said about Popper. > [@](#): > > However, “There’s no milk in the fridge.” is not a scientific theory. It’s a simple assertion of fact that can, in fact, be proved true by empirical observation. Not so. Why should a blind man believe what you say you’ve observed and accept it as truth? > [@](#): > > Second, just because Karl Popper says it, doesn’t make it so. You’re arguing from authority which is just another logical fallacy. Setting aside that you’ve mutilated my point with respect to Popper, arguing from authority is not necessarily a logical fallacy (or more precisely, a rhetorical vice) when the authority is indeed an authority on the topic. See [Argumentum ad verecundiam](http://www.infidels.org/news/atheism/logic.html#authority). Since Popper conceived the notion of falsification and applied it to science, it stands to reason that he is an authority on it. > [@](#): > > One would be tempted to think, here, that you are trying to intimidate with obscure words. Unless you can point out a grammatically ambiguous sentence in my post that changes its entire meaning? Your temptations notwithstanding, I did that. You used phrases that made no sense, like “testable definition”. > [@](#): > > Well, I can’t right now prove that a soul exists, but it’s at least \* conceivable \*that someday one could, somehow, detect the presence of an intangible information-bearing component of an intelligent being that persists after its demise. However, by the way it’s defined, you could never prove that it doesn’t exist. Nonsense. You’re just redefining it as “an intangible information-bearing component…”. I can prove that pigs fly by redefining “fly” to mean “wallow in mud”. > [@](#): > > This is obvious to us all. So, everybody got together and handed you the megaphone. What rule of logic are you citing when you imply that your opponent is an idiot? > [@](#): > > BTW, I’m not convinced that Peano’s axioms buy you an increased belief in the truth of 1+1, given that they are, after all, axioms. Which of the axioms do you reject, and why? ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [July 25, 2005, 7:44pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/50 "2005-07-25T19:44:21Z")
[QUOTE=Liberal] Not so. Why should a blind man believe what you say you’ve observed and accept it as truth? [quote] Hearken back to what I said about “navel gazing philosophy”. Why should a blind man be any more willing to believe your logical proofs about the existence of milk than my assertion that I went to a refrigerator, looked into it and saw that there was no milk? And frankly, if the blind guy wants to go the fridge, twist the cap off every bottle and sniff away, I have no objections. That’s the nice thing about empirical observations – they can be replicated. And by the way, a testable predicate is simply a feature of using logic in the “real” world; propositions are likely to be empirically derived. You want to start reasoning about “green cats”, then you need a “real-world” predicate colorOfCat?(X). It’s not that complicated. > [@](#): > > Setting aside that you’ve mutilated my point with respect to Popper, arguing from authority is not necessarily a logical fallacy (or more precisely, a rhetorical vice) when the authority is indeed an authority on the topic. See [Argumentum ad verecundiam](http://www.infidels.org/news/atheism/logic.html#authority). Since Popper conceived the notion of falsification and applied it to science, it stands to reason that he is an authority on it. He is an authority on falsification. However, it does not mean that every pronouncement he makes is true. Nor, and more saliently, does it mean that your misconception of what he’s talking about is true. > [@](#): > > Your temptations notwithstanding, I did that. You used phrases that made no sense, like “testable definition”. Sadly, I used no such phrase. The closest I came was in sentence “Because even if I turn out my pocket, the definition of “soul” is untestable – it’s invisible, massless and has no detectable properties.” And you’d be mighty hard-pressed to call this either “equivocation” or “amphiboly” as the second phrase in that sentence makes my meaning crystal clear to even the meanest intellect. So either you were trying to intimidate with the use of those words or \* you don’t understand what they mean\*. Feel free to choose whichever alternative is the least embarassing to you. > [@](#): > > So, everybody got together and handed you the megaphone. What rule of logic are you citing when you imply that your opponent is an idiot? In this case, it’s empirical observation. ---
**Author:** ![Liberal](https://avatars.discourse-cdn.com/v4/letter/l/848f3c/32.png) [@Liberal](https://boards.straightdope.com/u/Liberal)\ **Post date:** [July 25, 2005, 8:10pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/51 "2005-07-25T20:10:16Z")
> [@Finagle](#): > > Hearken back to what I said about “navel gazing philosophy”. I think that the one engaged in navel gazing is you. > [@](#): > > Why should a blind man be any more willing to believe your logical proofs about the existence of milk than my assertion that I went to a refrigerator, looked into it and saw that there was no milk? Because you might be a liar, or simply mistaken, or not know what milk is, or any number of other reasons. > [@](#): > > And frankly, if the blind guy wants to go the fridge, twist the cap off every bottle and sniff away, I have no objections. That’s the nice thing about empirical observations – they can be replicated. So can logical proofs. So what? Besides, how will Helen Keller determine whether there’s milk in the fridge using your method? Suppose she has a head cold. By your reasoning, a thing cannot be true without an observer. And that’s ridiculous. > [@](#): > > And by the way, a testable predicate is simply a feature of using logic in the “real” world; propositions are likely to be empirically derived. You want to start reasoning about “green cats”, then you need a “real-world” predicate colorOfCat?(X). It’s not that complicated. You’re just making stuff up. > [@](#): > > He is an authority on falsification. However, it does not mean that every pronouncement he makes is true. Nor, and more saliently, does it mean that your misconception of what he’s talking about is true. What exactly do you imagine that I have misconceived? You’re making things up that I said, like “every pronouncement he makes is true”. Is there a more desperate tactic of argument than arguing against things you make up yourself? > [@](#): > > Sadly, I used no such phrase. The closest I came was in sentence “Because even if I turn out my pocket, the definition of “soul” is untestable – it’s invisible, massless and has no detectable properties.” And you’d be mighty hard-pressed to call this either “equivocation” or “amphiboly” as the second phrase in that sentence makes my meaning crystal clear to even the meanest intellect. So either you were trying to intimidate with the use of those words or \* you don’t understand what they mean\*. Feel free to choose whichever alternative is the least embarassing to you. False dichotomy. Science doesn’t test definitions. It tests hypotheses. How a definition may be tested — and for what — is completely unclear. > [@](#): > > In this case, it’s empirical observation. I take that to mean that you know of no rule of logic that entitles you to call your opponent an idiot, and that you therefore argue hypocritically — pulling perceived logical fallacies out your ass when it suits you, and denying they exist when they apply to you. What I have observed is that you have succeeded in butchering your original point, which had some merit, into a baffling batch of nonsequiturs and nonsense. ---
**Author:** ![Askia](https://avatars.discourse-cdn.com/v4/letter/a/96bed5/32.png) [@Askia](https://boards.straightdope.com/u/Askia)\ **Post date:** [July 25, 2005, 8:20pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/52 "2005-07-25T20:20:50Z")
The only thing useful I’ve gained in this thread is that **Liberal** eats green cats with a fork. With that image guiding you til suppertime, dear reader, read on. ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [July 25, 2005, 8:26pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/53 "2005-07-25T20:26:41Z")
> [@Liberal](#): > > have succeeded in butchering your original point, which had some merit, into a baffling batch of nonsequiturs and nonsense. My original point was very simple. It was that there are things that many people believe in – souls, ghosts, gods, wild conspiracy theories – whose existence can not be disproved, logically or empirically. And I’m not the one who complicated it. Further, I think your OP is a wilful misunderstanding of the phrase “You can’t prove a negative.” Unless you’re a complete pedant, it’s obvious that the people saying that are not referring to trivial logical syntactic operations. It is clearly meant to mean one of two things: a. That would have to be proved by exhaustive search which is impossible in any non-trivial world. b. The thing that you are postulating has no properties that can be tested for and is therefore not in the domain that science is interested in. (BTW, Helen Keller could easily identify a milk bottle either by the taste or by the distinctive shape and raised lettering on the bottle. Not that arguing that some people lack certain senses \* in any way \* weakens the empirical method. It merely means that you’re willing to split infinite hairs in order to avoid admitting that you were wrong when you stated that nothing can be proved empirically.) ---
**Author:** ![Liberal](https://avatars.discourse-cdn.com/v4/letter/l/848f3c/32.png) [@Liberal](https://boards.straightdope.com/u/Liberal)\ **Post date:** [July 26, 2005, 10:50am UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/54 "2005-07-26T10:50:50Z")
> [@Finagle](#): > > My original point was very simple. It was that there are things that many people believe in – souls, ghosts, gods, wild conspiracy theories – whose existence can not be disproved, logically or empirically. And I’m not the one who complicated it. You’re part right, part wrong, and part incomplete — as I’ve alread explained in quite some detail. > [@](#): > > Further, I think your OP is a wilful misunderstanding of the phrase “You can’t prove a negative.” Willful? You can’t trust that Peano’s Axioms are true, but you trust yourself to read minds? > [@](#): > > Unless you’re a complete pedant, it’s obvious that the people saying that are not referring to trivial logical syntactic operations. Neither was I. I said that _some_ proofs of negatives are trivially easy. Some are not. Some are more difficult. > [@](#): > > It is clearly meant to mean one of two things: > > a. That would have to be proved by exhaustive search which is impossible in any non-trivial world. > b. The thing that you are postulating has no properties that can be tested for and is therefore not in the domain that science is interested in. Why you would link “science” to “proof” of anything at all is unclear. > [@](#): > > (BTW, Helen Keller could easily identify a milk bottle either by the taste or by the distinctive shape and raised lettering on the bottle. I stipulated that she has a head cold. And not all milk comes in bottles. Maybe it’s a carton. > [@](#): > > Not that arguing that some people lack certain senses \* in any way \* weakens the empirical method. It merely means that you’re willing to split infinite hairs in order to avoid admitting that you were wrong when you stated that nothing can be proved empirically.) Hairs? You consider the difference between deduction and induction to be a hair? No wonder you can’t grasp any of this. ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [July 26, 2005, 1:13pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/55 "2005-07-26T13:13:45Z")
> [@Liberal](#): > > I stipulated that she has a head cold. And not all milk comes in bottles. Maybe it’s a carton. > > Hairs? You consider the difference between deduction and induction to be a hair? No wonder you can’t grasp any of this. You’re gonna have to point to the part where I missed the distinction between deduction and induction. Because I think you used a new logical technique called “imagining it” to figure that one out. And, btw, when Helen Keller was alive, there were no milk cartons. Probably no fridges either, but ice boxes are close enough. Not that it matters – all your caveats about observers with perceptual defects and trust issues have absolutely nothing to do with the arguments I’m presenting. ---
**Author:** ![Gfactor](https://avatars.discourse-cdn.com/v4/letter/g/9de053/32.png) [@Gfactor](https://boards.straightdope.com/u/Gfactor)\ **Post date:** [July 26, 2005, 2:02pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/56 "2005-07-26T14:02:46Z")
> [@Finagle](#): > > It merely means that you’re willing to split infinite hairs in order to avoid admitting that you were wrong when you stated that nothing can be proved empirically.) > [@](#): > > David Hume addressed this problem in the 18th century in a particularly influential way, and no analysis since has managed to evade Hume’s critique. Hume looked at ways to justify inductive thinking. He pointed out that justifying induction on the grounds that it has worked in the past begs the question. That is, it is using inductive reasoning to justify induction. Circular arguments are valid, but do not provide a satisfactory justification for the supposition they claim to support. Prior to Hume, Sir Francis Bacon had made a strong claim that science was based on induction. Sir Karl Popper sought to ‘bypass’ the problem in the philosophy of science by arguing that science does not actually rely on induction, developing the notion of falsification instead. Popper replaced induction with deduction, in effect making modus tollens the centerpiece of his theory. On this account, when assessing a theory one should pay greater heed to data which is in disagreement with the theory than to data which is in agreement with it. Popper went further and stated that a hypothesis which does not allow of such experimental test is outside the bounds of science. > **[Problem of induction](https://en.wikipedia.org/wiki/Problem_of_induction)** > > Core concepts > Distinctions > Schools of thought Hardly splitting hairs. This is possibly the biggest issue in the philosophy of science. > [@](#): > > The problem of induction is one of considerable debate and importance in the philosophy of science: is induction indeed justified, and if so, how? > **[Philosophy of science](https://en.wikipedia.org/wiki/Philosophy_of_science)** > > Traditions by region > Philosophy of science is a branch of philosophy concerned with the foundations, methods, and implications of science. The central questions of this study concern what qualifies as science, the reliability of scientific theories, and the ultimate purpose of science. This discipline overlaps with metaphysics, ontology, and epistemology, for example, when it explores the relationship between science and truth. Philosophy of science focuses on metaphysical, epistemic and seman... The section of this article titled “The justification of scientific statements” is a particularly helpful summary. ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [July 26, 2005, 2:17pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/57 "2005-07-26T14:17:16Z")
> [@Gfactor](#): > > [http://en.wikipedia.org/wiki/Problem\_of\_induction](http://en.wikipedia.org/wiki/Problem_of_induction) > > Hardly splitting hairs. This is possibly the biggest issue in the philosophy of science. > > [http://en.wikipedia.org/wiki/Philosophy\_of\_science](http://en.wikipedia.org/wiki/Philosophy_of_science) > > The section of this article titled “The justification of scientific statements” is a particularly helpful summary. Thanks, Gfactor, but I’m aware of these works. The issue is not whether the scientific method relies on induction and falsification. I’m perfectly happy to admit that it does. But Liberal made a far more sweeping claim. He claimed that \* nothing \* could be proved empirically. Specifically, he said “Nothing can be proved true by empirical observation. Empiricism can only prove things false. That is not a contingency of negation, but of the epistemic nature of empiricism.” Note that Liberal did not qualify the above statement to limit it to the scientific method. So even the trivial statement, “There is a sunflower in my garden.” cannot, according to Liberal, be proved true despite the fact that I can see it from where I sit. I don’t see where induction comes into play here. I’m not making any assumptions about all sunflowers or all gardens. Now I understand how a casual reader of this thread might think I’m making claims about induction and deduction because there are two concurrent arguments going on, the argument that Liberal thinks he is having and the one that everyone else is reading. ---
**Author:** ![Liberal](https://avatars.discourse-cdn.com/v4/letter/l/848f3c/32.png) [@Liberal](https://boards.straightdope.com/u/Liberal)\ **Post date:** [July 26, 2005, 2:38pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/58 "2005-07-26T14:38:10Z")
> [@Finagle](#): > > So even the trivial statement, “There is a sunflower in my garden.” cannot, according to Liberal, be proved true despite the fact that I can see it from where I sit. No, that’s not right. It has nothing to do with whether you can or cannot see it. It has to do with _drawing an inference from what you have seen to truth_. You seem to be incapable of resisting an affirmation of the consequent. Induction includes the scientific method, but the scientific method does not include all induction. That’s why a deductive method works for proving 1 + 1 = 2, whereas an inductive method fails — the conclusion is one stipulation included in the broader set of stipulations. It doesn’t matter how many times you see adding one object to another object **or if you never see it at all** ; 1 + 1 will always equal 2 because deduction has proved it. ---
**Author:** ![Gfactor](https://avatars.discourse-cdn.com/v4/letter/g/9de053/32.png) [@Gfactor](https://boards.straightdope.com/u/Gfactor)\ **Post date:** [July 26, 2005, 3:01pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/59 "2005-07-26T15:01:08Z")
> [@Liberal](#): > > No, that’s not right. It has nothing to do with whether you can or cannot see it. It has to do with _drawing an inference from what you have seen to truth_. You seem to be incapable of resisting an affirmation of the consequent. Induction includes the scientific method, but the scientific method does not include all induction. That’s why a deductive method works for proving 1 + 1 = 2, whereas an inductive method fails — the conclusion is one stipulation included in the broader set of stipulations. It doesn’t matter how many times you see adding one object to another object **or if you never see it at all** ; 1 + 1 will always equal 2 because deduction has proved it. You might say it is definitional, or a tautology even. We aren’t adding anything to the system by repeatedly examining the sum of 1 + 1. In effect, we aren’t doing science at all. > [@Finagle](#): > > Note that Liberal did not qualify the above statement to limit it to the scientific method. So even the trivial statement, “There is a sunflower in my garden.” cannot, according to Liberal, be proved true despite the fact that I can see it from where I sit. I don’t see where induction comes into play here. I’m not making any assumptions about all sunflowers or all gardens. Check out this example, which I just ripped from the healines . . . sort of. . . [http://www.cnn.com/2005/TECH/science/07/22/woodpecker.question.ap/index.html](http://www.cnn.com/2005/TECH/science/07/22/woodpecker.question.ap/index.html) Put more theoretically . . . > [@](#): > > Theory-dependence of observation > > A scientific method depends on observation, in defining the subject under investigation and in performing experiments. > > Observation involves perception, and so is a cognitive process. That is, one does not make an observation passively, but is actively involved in distinguishing the thing being observed from surrounding sensory data. Therefore, observations depend on some underlying understanding of the way in which the world functions, and that understanding may influence what is perceived, noticed, or deemed worthy of consideration. (See the Sapir-Whorf hypothesis for an early version of this understanding of the impact of cultural artifacts on our perceptions of the world.) > > Empirical observation is supposedly used to determine the acceptability of some hypothesis within a theory. When someone claims to have made an observation, it is reasonable to ask them to justify their claim. Such a justification must make reference to the theory - operational definitions and hypotheses - in which the observation is embedded. That is, the observation is a component of the theory that also contains the hypothesis it either verifies or falsifies. But this means that the observation cannot serve as a neutral arbiter between competing hypotheses. Observation could only do this “neutrally” if it were independent of the theory. > > Thomas Kuhn denied that it is ever possible to isolate the theory being tested from the influence of the theory in which the observations are grounded. He argued that observations always rely on a specific paradigm, and that it is not possible to evaluate competing paradigms independently. By “paradigm” he meant, essentially, a logically consistent “portrait” of the world, one that involves no logical contradictions. More than one such logically consistent construct can each paint a usable likeness of the world, but it is pointless to pit them against each other, theory against theory. Neither is a standard by which the other can be judged. Instead, the question is which “portrait” is judged by some set of people to promise the most in terms of “puzzle solving”. > > For Kuhn, the choice of paradigm was sustained by, but not ultimately determined by, logical processes. The individual’s choice between paradigms involves setting two or more “portraits" against the world and deciding which likeness is most promising. In the case of a general acceptance of one paradigm or another, Kuhn believed that it represented the consensus of the community of scientists. Acceptance or rejection of some paradigm is, he argued, more a social than a logical process. > > That observation is embedded in theory does not mean that observations are irrelevant to science. Scientific understanding derives from observation, but the acceptance of scientific statements is dependent on the related theoretical background or paradigm as well as on observation. Coherentism and scepticism offer alternatives to foundationalism for dealing with the difficulty of grounding scientific theories in something more than observations. > **[Scientific method](https://en.wikipedia.org/wiki/Scientific_method)** > > The scientific method is an empirical method of acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries). It involves careful observation, applying rigorous skepticism about what is observed, given that cognitive assumptions can distort how one interprets the observation. It involves formulating hypotheses, via induction, based on such observations; experimental and measurement-based testing of dedu... You aren’t making any assumptions? 1. How do you know what you are seeing? 2. How can you be sure that you aren’t hallucinating? 3. How can you be sure it’s a sunflower? ---
**Author:** ![Finagle](https://avatars.discourse-cdn.com/v4/letter/f/b19c9b/32.png) [@Finagle](https://boards.straightdope.com/u/Finagle)\ **Post date:** [July 26, 2005, 3:37pm UTC](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846/60 "2005-07-26T15:37:59Z")
> [@Gfactor](#): > > You aren’t making any assumptions? Please read my post again. I said I wasn’t making assumptions about \* all \* sunflowers. The perceptual assumptions I’m forced to make about my own sunflower due to my sensory apparatus aren’t particularly interesting in the context of this argument. > [@](#): > > 1. How do you know what you are seeing? > 2. How can you be sure that you aren’t hallucinating? > 3. How can you be sure it’s a sunflower? See, this is why I made my snide comment about navel gazing. Any philosophical debate can be derailed by an appeal to the fallibility or subjective nature of the senses. And ultimately, that path doesn’t lead you anywhere useful because you just end up concluding that you can’t be sure of anything (except that you could use a drink). If you want to go down this path, then you basically are demonstrating the whole “You can’t prove a negative thing” because you leave me with no tools to prove that it isn’t a sunflower, that I’m not hallucinating, and so on. (Of course, in this case, “You can’t prove a negative” is just a subset of “You can’t prove anything.”) [Previous page](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846.md?page=2) [Next page](https://boards.straightdope.com/t/yes-dammit-one-can-prove-a-fucking-negative/313846.md?page=4)