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Author Topic:   Abductive Reasoning In Science
PaulK
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Message 16 of 120 (672315)
09-06-2012 1:25 PM
Reply to: Message 15 by Modulous
09-06-2012 1:16 PM


I think that "rational" would be better than "logical" in this context. The limits of pure deductive logic are well known, by the way. That's why science is an empirical enterprise.

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PaulK
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Message 34 of 120 (672337)
09-07-2012 1:30 AM
Reply to: Message 26 by crashfrog
09-06-2012 10:45 PM


quote:
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. Or, for that matter, induction. Many philosophers of science have construed this as a problem with empiricism and abduction - Hume's inductive fallacy, for instance.
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:
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
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:
That may be, because I like to keep "valid" distinct from "true." A proposition in logic is valid when it descends from premises by means of logical transformations that preserve truth values. A proposition in logic is true when it descends validly from premises that are true. Most of the time. Of course, per Godel, under some circumstances a proposition can be valid but not true.
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:
I guess what I'm getting at is, I'm much less interested in whether abductive reasoning is logically valid, since it is useful and true, which is more important.
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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PaulK
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Posts: 17822
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Member Rating: 2.2


Message 43 of 120 (672375)
09-07-2012 2:30 PM
Reply to: Message 42 by RAZD
09-07-2012 1:47 PM


Re: hypothesis
So would you agree that a theory is believed on inductive or abductive grounds ?

This message is a reply to:
 Message 42 by RAZD, posted 09-07-2012 1:47 PM RAZD has replied

Replies to this message:
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PaulK
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Posts: 17822
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Member Rating: 2.2


Message 57 of 120 (672435)
09-08-2012 2:56 AM
Reply to: Message 50 by RAZD
09-07-2012 7:20 PM


Re: theory acceptance and as a good working model
Firstky, let us be clear that a theory is not something that can be falsified as easily as a hypothesis. What you have described works well for testing a hypothesis but would generally cause a theory to be revised rather than discarded.
quote:
I would say that a theory (a tested & not invalidated hypothesis) is tentatively accepted as a good\valid working model based on abductive reasoning -- it hasn't been invalidated by current testing, but still can be invalidated by new testing -- that it is a good working model to predict\apply to new situations.
deductive element:
  • the hypothesis was tested for (new) predicted situations
  • the hypothesis was not invalidated by any of the new situations
  • therefore the hypothesis is valid for the new predicted situations as well as (all) old situations

Here, you have run headfirst into the problem of induction. Testing a hypothesis under new conditions is certainly useful but not for your "deduction" (which is not valid). Indeed it would seem to be an abduction i.e. success in the test is better explained by the hypothesis applying, rather than chance, or some more convoluted explanation.
In fact you seem to be assuming that the problem of induction is simply our practical inability to test all possible conditions. This is not so. We cannot deductively determine that our hypothesis works under any particular set of conditions merely by testing it. Falsification is deductive, confirmation under such tests is always inductive.
quote:
abductive element:
  • it is rational to use the theory to predict the results of new situations.

Presumably given the results of testing under a sufficiently large number of variations -including all suspected of being relevant.
But for theories there is more than this. The theory of evolution offered a framework to understand the hierarchy of taxonomic classification, biogeographic distribution and the fossil record. This presented a strong abductive ground to accept the theory on the grounds of explanatory power.

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Replies to this message:
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PaulK
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Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 62 of 120 (672456)
09-08-2012 12:50 PM
Reply to: Message 61 by RAZD
09-08-2012 12:18 PM


Re: theory acceptance and as a good working model
quote:
That is my point, the analysis of the new data is deductive: does it falsify the hypothesis or not (presumably such analysis has already been done for any old data)? If the new data does not falsify the hypothesis then you can move on to the next step.
Then you are only seeing the half of it. The failure to falsify does not deductively justify any use of the theory as a model at all. Even under the tested circumstances. For that you need other reasoning.
quote:
Sorry about my lack of clarity here, and I'll clarify my conclusion in my previous post as follows:
• therefore the hypothesis is valid for the new predicted* tested situations as well as (all) old situations.

But that is what I understood you to be saying - and that conclusion can only be justified inductively or abductively. My point stands.

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 Message 61 by RAZD, posted 09-08-2012 12:18 PM RAZD has replied

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PaulK
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Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 66 of 120 (672462)
09-08-2012 1:42 PM
Reply to: Message 65 by RAZD
09-08-2012 1:36 PM


Re: theory acceptance and as a good working model
quote:
Is this not a deductive analysis of the new information?
As I said falsification is deductive. I don't see anything significant in what you are saying here.
quote:
Correct: the analysis of the new data half, not the inductive hypothesis half, where you induce that it applies outside the tested set of data. That is the "next step" after the analysis.
You're still missing it. The idea that it applies within the tested data is not deductively true. You need induction or abduction to even conclude that. Indeed, the conclusion that you achieved the expected result in the test because the theory worked is an abductively conclusion.

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PaulK
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Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 69 of 120 (672487)
09-08-2012 6:48 PM
Reply to: Message 67 by RAZD
09-08-2012 1:50 PM


Re: theory acceptance and as a good working model
quote:
It applies to the analysis of the data not "within the tested data" sheesh.
Only if the "analysis of the data" is restricted to determining if the theory has been falsified or not.
But that is not enough for "acceptance of the theory" even tentatively "as a working model". For that you need to apply induction or abduction as I keep telling you.

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PaulK
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Member Rating: 2.2


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Message 73 of 120 (672521)
09-09-2012 4:37 AM
Reply to: Message 71 by nwr
09-08-2012 11:43 PM


Re: Before Abductive, Inductive, or Deductive reasoning ...
The thing striking me in the face is the obvious fact that your description of philosophers better fits yourself than anyone else.
To raise one simple example the question of which reasoning modes are employed in science is best decided by looking at actual scientific reasoning rather than by abstract reasoning. (Even good abstract reasoning).
Please bow out of this thread. I don't want to see another train wreck like your attempt to "prove" that scientists can't use induction.

This message is a reply to:
 Message 71 by nwr, posted 09-08-2012 11:43 PM nwr has replied

Replies to this message:
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PaulK
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Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 75 of 120 (672538)
09-09-2012 9:23 AM
Reply to: Message 74 by Dr Adequate
09-09-2012 7:28 AM


Re: Before Abductive, Inductive, or Deductive reasoning ...
Even if that was correct he'd only be right by accident, having no valid argument or understanding of the reasoning used by scientists. However in my view the whole idea of a hypothesis being corroborated by repeated failures to falsify it is an example of inductive reasoning, and any claim that science doesn't use induction at all would certainly need to provide an alternative explanation of the reasoning used in that case.

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PaulK
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Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 91 of 120 (672744)
09-11-2012 1:28 AM
Reply to: Message 88 by RAZD
09-10-2012 7:21 PM


Re: theory acceptance and as a good working model
However if we compare the actual painting to genuine works by elephants (who also seem to need training and human guidance) or by apes we can see that it is extremely unlikely that it was produced by either. The simple hypothesis might be falsified but a closer look shows us no real alternative to a human source for this particular painting.
So, RAZD, do you accept that this painting was created by a human being or not ?

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PaulK
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Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


(1)
Message 100 of 120 (672867)
09-12-2012 1:46 AM
Reply to: Message 99 by RAZD
09-11-2012 6:43 PM


Re: still a falsified and in need of modification hypothesis ...
Of course there's nothing important in the context of this discussion to ignore. Even without a formal survey we still have a strong abductive argument for assigning the painting to a human creator - which goes to show that abduction is rather more than a mere guess. Now THAT is an important point.

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PaulK
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Posts: 17822
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Member Rating: 2.2


Message 106 of 120 (673297)
09-18-2012 1:08 PM
Reply to: Message 105 by Hawkins
09-18-2012 12:57 PM


quote:
Evolution is an implicit (if not explicit) claim that all living organisms are a result of evolution from a single cell (or whatever primitive life from).
Actually, evolution itself doesn't claim this. But it is (more or less) what we infer from the evidence. (There are some significant complications at the very root of the tree, but I don't think that they are important now).
quote:
However, there's never any predictable observation of any (or over 99.99%) living organisms can actually evolve from a SINGLE CELL!!!
Evidence that something HAS happened is evidence that it could.
quote:
A scientific theory is a speculation that something will repeat by following a set of rules.
Well, we'll go with that for now, but the outcome of the rules are not always predictable even in quite simple physical systems (see Chaos theory).
quote:
A hypothesis is a suggestion on how such a repetition shall repeat but not yet proven. This can be further divided into 2 categories, 1) by observation we already know its repeating pattern but we can't yet make the set of rule behind it proven, and 2) we can't actually obtain an empirical observation to say that it actually repeats with a pattern. But based on the assumption that it can repeat that we start to develop a theory behind its repetition.
So the tree structures we observe in taxonomy and genetics would qualify, correct ? And we can predict that any new lifeform discovered will fit into those trees correct ? And they do.
So there you are.

This message is a reply to:
 Message 105 by Hawkins, posted 09-18-2012 12:57 PM Hawkins has replied

Replies to this message:
 Message 107 by Hawkins, posted 09-18-2012 1:22 PM PaulK has replied

  
PaulK
Member
Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 108 of 120 (673304)
09-18-2012 1:36 PM
Reply to: Message 107 by Hawkins
09-18-2012 1:22 PM


quote:
That's actually where your misconception coming from.
Whatever evidence you have for a plant,
1) it can't be a proof of ALL PlANTS!!!
2) it can't be a proof of NON PLANTS such as animals
this is your fallacy applied,
Because a species of plants evolved, such that all plants must have evolved from a single cell.
Of course we are not talking about just A plant. We are talking about ALL earthly life. We may not have the genetic data for every known species, but we do have the data used for taxonomy.
So the fallacy is yours, as shown by your dismissal of evidence you can't even understand.
quote:
"that it could" means,
1) it is not science. Science is much more than just showing that "it could"
2) "it could" is almost a faith statement demanding faith to believe (it's not scientific anyway).
The fallacy you have to apply here is,
Because 'it could' such that 'it must be'.
Of course the fallacy is yours. You claimed that there was no evidence that it could happen. My point is that we have evidence that it did happen - which is evidence that it could happen.
And it is certainly not fallacious to say that evidence that something did happen is evidence that it happened. Indeed to claim otherwise - as you do - is to reject all logic.

This message is a reply to:
 Message 107 by Hawkins, posted 09-18-2012 1:22 PM Hawkins has replied

Replies to this message:
 Message 109 by Hawkins, posted 09-18-2012 1:42 PM PaulK has replied

  
PaulK
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Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 110 of 120 (673306)
09-18-2012 1:47 PM
Reply to: Message 109 by Hawkins
09-18-2012 1:42 PM


quote:
show me then!
I've already told you what that evidence is. For instance we might point out the eukaryotic cell - ALL animals and ALL plants have this form of cell. There are single celled eukaryotes, too. Or another, aside from minor variations, the genetic code is the same in ALL DNA-based life. And there is more, much more uniting all life. Taxonomy and genetics speak to the truth of common ancestry of all life.

This message is a reply to:
 Message 109 by Hawkins, posted 09-18-2012 1:42 PM Hawkins has replied

Replies to this message:
 Message 111 by Hawkins, posted 09-18-2012 1:49 PM PaulK has replied

  
PaulK
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Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


(1)
Message 112 of 120 (673308)
09-18-2012 2:03 PM
Reply to: Message 111 by Hawkins
09-18-2012 1:49 PM


quote:
Jesus Christ. Answer me!
Such that all of human must have been evolved from a single cell? You call that a justified proof? It's a joke.
"Because ALL animals and ALL plants have this form of cell such that they must have been evolved from a single cell".
It is the exact statement showing where your fallacy is!
Except, of course I told you that these were examples of the EVIDENCE not proof in themselves. So your "fallacy" is simply your own invention.
Now are you going to discuss the matter honestly ? Or are you going to simply go on with your refusal to even understand the evidence and the arguments ? Because I have better things to do than with my time trying to spoon feed you arguments and facts that you can't be bothered to listen to.

This message is a reply to:
 Message 111 by Hawkins, posted 09-18-2012 1:49 PM Hawkins has replied

Replies to this message:
 Message 113 by Hawkins, posted 09-18-2012 2:50 PM PaulK has replied

  
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