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Member (Idle past 93 days) Posts: 10333 From: London England Joined: |
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Author | Topic: Abductive Reasoning In Science | |||||||||||||||||||||||||||||||||||||||
Dr Adequate Member (Idle past 311 days) Posts: 16113 Joined:
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I'm not sure I quite understand the distinction between inductive reasoning and abductive reasoning. Well, they're completely different. (In talking about this, I'll just go with how WP defines abductive reasoning, it is possible that they are misdefining it, there are some strange confusions in the article.) Inductive reasoning goes like this: "I have a theory about how the world works. This theory predicts A, B, and C. I observe A, B, and C. So I shall take this theory to be true until and unless I find a counterexample to this general rule." Abductive reasoning goes like this: "I have a theory about how the world works (hopefully one confirmed by inductive reasoning). I observe Y. According to my theory, the only possible explanations for Y are X1, X2, or X3. Therefore, one of X1, X2, or X3 must be true." But as I say, the WP article is just odd. Sometimes it says one thing (which I would agree with completely) and sometimes it says another thing (which I would not endorse) and sometimes it says things that seem to me to be nonsensical (and I am not noted for being obtuse, so I think the fault lies with them and not me).
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Dr Adequate Member (Idle past 311 days) Posts: 16113 Joined: |
In this thread I don't think it is for me to stipulate what is "valid" and what is not. Quite right. That's my job.
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Dr Adequate Member (Idle past 311 days) Posts: 16113 Joined: |
I choose to construe the issue as being a problem with logic, one that largely relegates logic to the status of an amusing parlor game as opposed to a useful tool for grappling with the world. I declare jihad.
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PaulK Member Posts: 17827 Joined: Member Rating: 2.3
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quote: But there isn't a real problem in reconciling them. Inductive and abductive modes of reasoning are fallible. That's all that declaring them "logically invalid" means.
quote: Formal deductive logic has the problem that it needs premises to reason from and can't produce them. And that's one reason why we need other modes of reasoning. Given premises, however, formal logic is useful and effective.
quote: However, validity is not a property of a proposition. It is a property of the argument that leads from the premises to the proposition. Your definition is not only non-standard, it is useless since any proposition may be derived by valid logic given a free choice of premises.
quote: The point that abductive reasoning is fallible and should be carefully employed is important, I think. Aside from that I cannot say that validity in strict deductive logic is greatly important in any argument, unless it is presented as an argument of strict deductive logic.
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Dr Adequate Member (Idle past 311 days) Posts: 16113 Joined:
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If I can avoid a "what do words mean" type of conversation by saying so, then let me try to clarify - I guess what I'm saying is that it's difficult to reconcile formal logic with empiricism or abduction. Well, yeah. It's also difficult to reconcile being a bicycle with being an umbrella. 'Cos they're different things. It's not that there's a contradiction between bicycles and umbrellas, it's that they do different things. Now, the role of logic in science is this: If you think a theory is true, you are obliged to think that the logical consequences of that theory are also true. If you believe in the theory of gravity, then logic compels you to also think that planets must orbit the sun in (to a high degree of approximation) ellipses. You can't believe the theory but dispute the conclusion, because the conclusion is a logical consequence of the theory. Now, the role of logic as I have just explained it has, clearly, a huge and important role in science. Logic is what connects a theory to its predictions. Without that, there would be no such thing as science. But that is all that it does. When we have finished bowing down before logic and praising it, that's the only thing it does in science. It is not a valid critique of logic to complain that that's all it does, because this is all that (in science) it claims to do. It connects your theory to your observations. It is equally not a critique of science to complain that it is not a logical procedure. Science is logical just insofar as it uses logic to connect theories with observations. Whenever we want to do anything else, then science does not follow the rules of logic, it follows the rules of science. When science is scientific, when (for example) it is empirical, then it is not illogical, it is alogical. The question of whether it is logical simply doesn't occur, it's a category error, it's like asking an Orthodox Jew to pronounce whether his dietary laws permit me to ride a unicycle. The question doesn't even apply to the subject, since I am not asking if it is lawful to eat a unicycle.
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crashfrog Member (Idle past 1494 days) Posts: 19762 From: Silver Spring, MD Joined: |
Does anybody not from the "disagree just to be disagreeable" crowd have anything to say?
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Dr Adequate Member (Idle past 311 days) Posts: 16113 Joined: |
Does anybody not from the "disagree just to be disagreeable" crowd have anything to say? In order to reply to that, one would first have to identify the ""disagree just to be disagreeable" crowd".
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Straggler Member (Idle past 93 days) Posts: 10333 From: London England Joined: |
I think you are over-complicating matters.
Abductive reasoning in science is effectively about limiting explanations to those that have a record of success and tentatively discarding the infinite array of other possibilities until there is some evidential reason to think they might be relevant.
BluJ writes: It sounds to me like abduction is just the action of proposing a hypothesis for a set of observations. If you see a painting of unknown origin it is reasonable to abduce that the painting in question was painted by a human rather than something that popped into existence ex-nihilo, or which was created by an alien, or which was painted by a particularly artistic badger or.....etc. etc. etc. etc.
BluJ writes: Your OP quote says abduction is equivalent to "affirming the consequent.... PREMISE: Humans have the capacity to produce paintings.FACT: Exhibit A is a painting CONCLUSION: Therefore exhibit A was produced by a human. This is an example of affirming the consequent. In deductive logical terms it is fallacious. That humans have the capacity to produce paintings doesn't mean that ALL paintings are necessarily created by humans. So the conclusion is potentially false and does not deductively follow from the premise. However given that we have no evidence of anything other than humans having created paintings (and lots of evidence that humans do create paintings) it is perfectly reasonable to abduce this deductively fallacious conclusion. Having accused you of over-complicating things I fear I am now doing the same even more so..... Edited by Straggler, : No reason given.
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Straggler Member (Idle past 93 days) Posts: 10333 From: London England Joined: |
Crash writes: I guess what I'm saying is that it's difficult to reconcile formal logic with empiricism or abduction. Or, for that matter, induction. As has been pointed out by others - The reason for this is because deductive reasoning is not the same as abduction (or induction). They are different things.
Crash writes: Many philosophers of science have construed this as a problem with empiricism and abduction - Hume's inductive fallacy, for instance. Well that is a fair point. Philosophers of science (most notably Popper I believe) have wrestled with the whole issue of science incorporating modes of reasoning that don't result in deductive certainty. It's part of the whole thorny issue of "truth" and what exactly it is that science is telling us about the world. The answers to these problems (in a simplistic nutshell) - Tentativity and verisimilitude.
Crash writes: I choose to construe the issue as being a problem with logic, one that largely relegates logic to the status of an amusing parlor game as opposed to a useful tool for grappling with the world. You go too far. Deductive logic is a crucial component of developing (and utilising) scientific theories. It just isn't the whole shebang!!
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Straggler Member (Idle past 93 days) Posts: 10333 From: London England Joined: |
In this thread I don't think it is for me to stipulate what is "valid" and what is not. Dr A writes: Quite right. That's my job. Well keep up the good work on that score.
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Straggler Member (Idle past 93 days) Posts: 10333 From: London England Joined: |
RAZD writes: Curiously, I thought evolution was developed from deductive reasoning from examples where it is known to occur (likewise the original Theory of Natural Selection), am I wrong? Yes you are wrong. Can you explain how the hypothesis that ALL life on Earth, including as yet undiscovered species, shares a common ancestor can be derived purely by a process of deductive logic from the available evidence? You need to start understanding the role of different logical forms of reasoning if you are ever to understand science and how it actually works.
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RAZD Member (Idle past 1432 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi Straggler,
Well I think you are still wrong. I think you are misunderstanding or under-estimating the role of abductive (and inductive) reasoning in the formation of scientific theories and hypotheses. Can you explain how the hypothesis that ... Logic (deductive, inductive, abductive) → hypothesis hypothesis → Logic (deductive): if true, then it follows that {predictions} must be true:
If all known {A} is also {B} (observation) And if {A} ≡ {B} (hypothesis) Then any new {B} is also {A} (prediction) {predictions} → testing testing → new information new information → analysis: it invalidates (contradicts) or it doesn't question (neither matches nor contradicts) prediction analysis → reformulate hypothesis and predictions as needed to include new information repeat Note that failure to invalidate the {predictions} does not necessarily support the hypothesis: the new information could be just more of the {A} that is also {B} subset and there could still be {B} ≠ {A} that has not been detected yet (and which would then invalidate the hypothesis).
As I understand it deductive logic cannot go from the specific to the general. So I am intrigued as to how you think any theory/hypothesis involving a generalised statement can be deductively derived from specific observable instances. You can deduce a cause → effect pattern from several observed instances, x causes y1 (something causes a rock to fall)*x causes y2 (something causes a pencil to fall) x causes y3 (something causes a feather to fall) ... x causes yn (something causes object n to fall, where n is the number of observations involved) deduction: the pattern of cause (gravity) and effect (things falling) is the same for all n objects. then generalize (inductive\abductive) as a general application of that cause → effect pattern: x causes all y (something - gravity - causes all these objects to fall) while, in contrast, the general application is derived from a single instance (inductive) or guessed (abductive). Feel free to correct this, as I'm not wedded to it, but this is the way I read\see the process. Enjoy. * ie - fall from the hand when released and landing at, or relatively near, your feet (or the base of the leaning tower of Pisa) Edited by RAZD, : clrty, format, examples added Edited by RAZD, : mo clrtyby our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)
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PaulK Member Posts: 17827 Joined: Member Rating: 2.3 |
So would you agree that a theory is believed on inductive or abductive grounds ?
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Straggler Member (Idle past 93 days) Posts: 10333 From: London England Joined: |
Ahhh. When in doubt pull out the Venn diagrams.....
RAZD writes: Curiously, I thought evolution was developed from deductive reasoning from examples where it is known to occur (likewise the original Theory of Natural Selection), am I wrong? Yes you are wrong. Can you explain how the theory that ALL life on Earth, including as yet undiscovered species, shares a common ancestor can be derived purely by a process of deductive logic from the available evidence? If you can't do this just say so.....
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Blue Jay Member (Idle past 2725 days) Posts: 2843 From: You couldn't pronounce it with your mouthparts Joined: |
Hi, Dr A.
Dr Adequate writes: Inductive reasoning goes like this: "I have a theory about how the world works. This theory predicts A, B, and C. I observe A, B, and C. So I shall take this theory to be true until and unless I find a counterexample to this general rule." Abductive reasoning goes like this: "I have a theory about how the world works (hopefully one confirmed by inductive reasoning). I observe Y. According to my theory, the only possible explanations for Y are X1, X2, or X3. Therefore, one of X1, X2, or X3 must be true." Oh, so my misunderstanding was more with what induction is: induction is not about explaining an observation at all, but about using observations to verify a theory, while abduction is about using a theory to explain observations.-Bluejay (a.k.a. Mantis, Thylacosmilus) Darwin loves you.
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