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Author Topic:   Abductive Reasoning In Science
Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


(1)
Message 8 of 120 (672210)
09-04-2012 6:03 PM
Reply to: Message 1 by Straggler
09-04-2012 1:33 PM


1) How widely is abductive reasoning used in science?
4) Can we 'do science' without abductive reasoning? Or is it a vital component of the scientific method?
Very widely, no, and yes, respectively.
Consider that we are performing abduction when we reason from "The litmus paper is this color" to "this solution is acidic" or from "the thermometer gives this reading" to "this liquid is hot".
2) Is abductive reasoning a valid tool for science to use in formulating theories?
That depends what you mean by theory. It does not allow us to produce grand general theories, but only theories in the sense of an explanation for a particular thing.
Why? Because abduction is only possible in the context of a theory. Suppose we have a patient with measles? What do we abduce? That depends on whether our theory of the causes of disease involves germs or witches.
3) What are some key examples of abductive reasoning relevant to the sort of science topics regularly covered at EvC (Evolution, Big Bang, Age of earth etc. etc. etc.)?
Well, the Big Bang can be abduced from the evidence plus the theory of relativity; it can then be made hypothetico-deductive, we reason forward from it to what we should see. Similarly with the age of the earth, we can abduce it from various physical and geological theories, we can then reason forward from it.
Evolution is interesting because nearly every datum wears two faces. Take intermediate forms, for example. We can reason forward from Darwinism to the existence of intermediate forms (a morphological judgement) and take their existence (and lots of other stuff too, obviously) as confirmation of the theory. But then in the light of the theory (once we have been convinced of it by this and other lines of evidence) we can interpret them as being transitional species, which is a historical judgement.
Again, consider chromosome 2. From our theory plus the fact that humans have one fewer chromosome than the other apes, we can deduce some things about what the human chromosome should look like and see if it does. The fact that we're right tends to confirm our theory. This is hypothetico-deductive reasoning. But once we have been convinced of the theory by this and other lines of evidence, we can abduce in the light of the theory that a chromosome fusion took place.
Being too stupid to understand the difference between these two modes of reasoning is of course part of the creationists' stock in trade.

This message is a reply to:
 Message 1 by Straggler, posted 09-04-2012 1:33 PM Straggler has replied

Replies to this message:
 Message 9 by Straggler, posted 09-04-2012 6:18 PM Dr Adequate has replied

  
Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


(3)
Message 12 of 120 (672220)
09-04-2012 7:04 PM
Reply to: Message 9 by Straggler
09-04-2012 6:18 PM


I don't think it is limited to creationists. I think rampant demands for the disproof of things designed to be disprovable and relentless accusations of "illogical arguments" whenever non-deductive modes of reasoning are applied to the origins of various unfalsifiable concepts show that the confusion is rife in even those who should know better......
Well what I mean is that (for example) creationists will complain that scientists assume that species are transitional, based on their theory.
Now, this isn't how it works. Scientists see that forms are intermediate. They conclude (from this and other evidence) that the theory is correct, since this is one of the things that it predicts. They they abduce that when they are looking at intermediate forms, they are looking at transitional species.
The creationist, naturally gifted with stupidity and determined to misunderstand everything you tell him, conflates seeing that the forms are intermediate with abducing that the species are transitional.
Again, consider the argument from morphology. The creationist pretends that scientists assume that similarity indicates relatedness rather than a common designer.
What actually happens? The theory predicts that we should be able to robustly classify organisms by means of a tree-like structure. We look, and we can. This tends to confirm our theory. Once we have been convinced by this and other lines of evidence that the theory is correct, we then abduce from the theory that the tree is in fact a family tree. Again, a sufficiently retarded creationist can conflate the two processes.
---
These examples demonstrate the importance of abduction to evolutionary biology. Roughly speaking, when we compare the predictions of the theory to the evidence found in the present, we are being hypothetico-deductive, but when we reconstruct the past history of evolution from the evidence, we are performing abduction in the light of the theory.
(I say "roughly speaking" because statements about history can be themselves subjected to hypothetico-deductive inquiry. For example, having abduced the relationship of birds to crocodiles from the fossil evidence, we have a prediction about the genetic evidence.)

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 Message 13 by Straggler, posted 09-06-2012 12:22 PM Dr Adequate has replied

  
Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 28 of 120 (672329)
09-06-2012 11:21 PM
Reply to: Message 13 by Straggler
09-06-2012 12:22 PM


A common creationist confusion along these lines pertains to dating, the geologic column and fossils. The creationist misunderstanding/complaint is based on thinking that fossils are dated by their position in the geologic column whilst the layers of the geologic column are dated by means of which fossils they contain.
I think that's a different mistake. I don't know if there's a formal name for it, so I hereby christen it "being a fucking halfwit".

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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


(1)
Message 29 of 120 (672330)
09-06-2012 11:26 PM
Reply to: Message 14 by crashfrog
09-06-2012 12:36 PM


I would go so far to suggest that if scientific abduction is illogical, that exposes a problem with logic, not with scientific abduction.
Actually, neither. Saying that this is "a problem with logic" is like saying that there's a problem with bicycles because they don't keep the rain off your head. But it is not really a "problem with bicycles" that they're not umbrellas. Logic does exactly what it is purported to do. It's not a problem with it that it doesn't do other things. A bicycle is not a defective umbrella, and logic is not a defective form of the scientific method.

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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 30 of 120 (672331)
09-06-2012 11:31 PM
Reply to: Message 18 by crashfrog
09-06-2012 1:38 PM


I grant that it is a mode of reasoning, but I'm not seeing how it's a mode of logical reasoning. By definition, the process of abduction is committing the formal fallacy of ad hoc, ergo propter hoc.
That's what wikipedia says, but it is at variance with their definition of abduction.

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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


(2)
Message 31 of 120 (672332)
09-06-2012 11:51 PM
Reply to: Message 21 by Blue Jay
09-06-2012 3:33 PM


Re: Abductive vs Inductive
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 284 days)
Posts: 16113
Joined: 07-20-2006


Message 32 of 120 (672333)
09-06-2012 11:53 PM
Reply to: Message 23 by Straggler
09-06-2012 4:03 PM


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 284 days)
Posts: 16113
Joined: 07-20-2006


Message 33 of 120 (672334)
09-06-2012 11:55 PM
Reply to: Message 26 by crashfrog
09-06-2012 10:45 PM


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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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


(2)
Message 35 of 120 (672339)
09-07-2012 2:19 AM
Reply to: Message 26 by crashfrog
09-06-2012 10:45 PM


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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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 37 of 120 (672350)
09-07-2012 8:17 AM
Reply to: Message 36 by crashfrog
09-07-2012 7:38 AM


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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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 46 of 120 (672401)
09-07-2012 5:08 PM
Reply to: Message 45 by Blue Jay
09-07-2012 4:48 PM


Re: Abductive vs Inductive
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 ...
Not quite. Induction is the leap from: "I always observe P to be true" to "P is always true."

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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 47 of 120 (672402)
09-07-2012 5:11 PM
Reply to: Message 3 by RAZD
09-04-2012 3:26 PM


Re: hypothesis
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're wrong. It is impossible to deduce a theory from the facts (in the strict meaning of "deduce"). This applies to any theory, not just evolution.

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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 74 of 120 (672526)
09-09-2012 7:28 AM
Reply to: Message 73 by PaulK
09-09-2012 4:37 AM


Re: Before Abductive, Inductive, or Deductive reasoning ...
To be fair, he does have a point about induction, though he overstates it. Science is not inductive, it's hypothetico-deductive. At best, induction is a description of a psychological phenomenon: if we see the sun rising in the east often enough, we may formulate a general law that that's what it does. But how we get the law is not really part of the scientific method, it's just a fact about how our brains tend to work.
What is curious about his objection is that he blames the concept of induction on philosophers, whereas it is minimizing the role of induction that is really an abstruse philosophical concept. It is completely obvious that science is inductive: it requires careful reasoning to discover that it isn't.
About abduction he is of course completely wrong.

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 Message 73 by PaulK, posted 09-09-2012 4:37 AM PaulK has replied

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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


(1)
Message 84 of 120 (672624)
09-10-2012 6:43 AM
Reply to: Message 76 by Blue Jay
09-09-2012 10:13 AM


Re: Before Abductive, Inductive, or Deductive reasoning ...
That doesn't sound right to me. Is there a way to arrive at a general law without inductive reasoning?
Well yes: you guess.
Consider Kepler, for example, formulating his laws. He could not see Brahe's data points as instances of a general law that the planets moved in ellipses until he had first guessed the law.
Now, sometimes observing something manifestly regular, such as the sun always rising in the east, will in fact inspire us to formulate a law; but it need not, one can imagine someone who never paid any attention to the position of the sun in the morning. It is still, I would say, necessary to think of the theory, or at least what sort of form the theory is going to take (i.e. "maybe the sun always rises in the same quarter") before one can see whether it's true by comparing it to the data.
After all, even in the most obvious case we need to pick out (consciously or unconsciously) something to reason inductively about from a great mass of data about the universe, none of which comes labeled: "do induction on this". Suppose that instead of choosing to do induction on "where is the sun every morning", you did induction on "what shape are all the blue things that I've seen", and tried to formulate a general rule, then that wouldn't work out so well. Now the choice is not made by induction: and yet it must be made somehow; something else is going on.
(It is, as I say, a psychological fact that in certain cases people will have a strong tendency to think of certain theories. But that's just an observation about how human beings roll.)
One can, of course, make inductive arguments in science; once one has a general law, one can say: "I always see the sun rise in the east, inductively it always will". (And then one could always reformulate that as a hypothetico-deductive argument, and it would gain in clarity what it lost in brevity.) But the inductive argument is not an account of how one came by the idea: you had to have the idea before you could produce an inductive argument to support it.
Edited by Dr Adequate, : No reason given.
Edited by Dr Adequate, : No reason given.
Edited by Dr Adequate, : No reason given.

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Dr Adequate
Member (Idle past 284 days)
Posts: 16113
Joined: 07-20-2006


Message 92 of 120 (672747)
09-11-2012 2:29 AM
Reply to: Message 90 by RAZD
09-10-2012 8:09 PM


Re: theory acceptance and as a good working model
There are a number of issues I could raise if I wanted to ...
Yeah, but why do you want to? So far as I can see you're just getting all picky about an example the actual purport of which you understand perfectly well, thus bogging down what might otherwise be an interesting discussion. It doesn't matter that one can train an elephant to use a paintbrush. Either just imagine they can't, or think of another example --- the construction of a car, for example. So far as I know, elephants can't do that.

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