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Author Topic:   Abductive Reasoning In Science
bluegenes
Member (Idle past 2477 days)
Posts: 3119
From: U.K.
Joined: 01-24-2007


Message 56 of 120 (672433)
09-08-2012 2:00 AM
Reply to: Message 49 by RAZD
09-07-2012 6:34 PM


Re: hypothesis
RAZD writes:
This seems to me to be especially true for the initial formation of the theory of natural selection by Darwin, as he listed a number of situations where selection (cause) appeared to affect population traits (effect).
That's observation. From those observations in particular species, he could make the inductive hypothesis that natural selection effected all organisms around the world in both present and past. This is inductive reasoning from Darwin's particular examples to the general, and cannot be proven by deductive logic.
Then, he could make an explanatory abductive hypothesis: that natural selection is the cause or driving force behind the "origin of species".
Deductive reasoning comes in at this point, and is very important. It is how we decide what would necessarily follow from the hypotheses that have been made. That's how we establish what their predictions are.
Science necessarily uses a lot of induction and abduction. That's why it's a mistake to criticise scientific laws and theories on the grounds that they are deductively fallacious. It can, however, be right to criticise a claimed prediction on the grounds that it is not deductively valid.
P1 Darwin's theory (of transition) is correct.
P2 Organisms fossilize
C: There will be "transitional" fossils.
If we're predicting transitional fossils from Darwin's theory, then that syllogism should be valid, but not, of course, necessarily sound, because we're using the inductive/abductive theory we're testing as one of the premises.
If suggested as a prediction, transitional fossils should be deductively necessary to the theory, not just compatible with it.

This message is a reply to:
 Message 49 by RAZD, posted 09-07-2012 6:34 PM RAZD has replied

Replies to this message:
 Message 63 by RAZD, posted 09-08-2012 1:11 PM bluegenes has replied

  
bluegenes
Member (Idle past 2477 days)
Posts: 3119
From: U.K.
Joined: 01-24-2007


Message 70 of 120 (672498)
09-08-2012 7:55 PM
Reply to: Message 63 by RAZD
09-08-2012 1:11 PM


Re: hypothesis and data analysis
RAZD writes:
P1: here is a list of observed situations regarding selection and population traits
P2: none of these situations invalidate the concept that selection affects population traits
C: therefore it is not invalid\irrational to conclude that selection affects population traits in these specific situations.
It would be deductively invalid to conclude that selection affects those populations in those situations from the information you've given there. You could conclude that by observation if you had observed it to be the case in all of the situations (your P1 didn't say that), but then you wouldn't need to deduce anything. Or you could conclude it by induction if you had observed it to be the case in some examples and there was no observed reason it couldn't be in the others. In which case, it's tentative of course.
RAZD writes:
The deductive element is the analysis of the data in relation to the hypothetical concept, and, IF the hypothetical concept is not invalidated, THEN you can move on to the "inductive hypothesis that natural selection effected* all organisms around the world in both present and past."
What's the "hypothetical concept" at this point, if you've already established the existence of natural selection as a phenomenon by observation? You seem to be describing the testing of an inductive hypothesis. Your only deduction is working out what would logically follow if your hypothesis was correct (its predictions, and therefore its falsifications). That may be (sort of) what you're meaning to say. But comparing data to the predictions is really testing by observation after the deductive reasoning has given you those predictions.
I think one way to describe the basis of Darwin's original theory briefly is that he abduces common descent (as an explanation of the apparent relationships seen in classification), induces the generality of the observed phenomenon of natural selection from particular examples, and abduces that hereditary variations and selection on them are the processes that lead to the origin of new features and species (as an explanation of how and why it came about that there's lots of organisms around, not just one or several originals).
Deduction comes in when it's used to determine what predictions those three hypotheses and the overall theory make. Because we determine the predictions (what should necessarily follow if the hypotheses are true) by deduction from the hypotheses, it follows that falsifications (any observations that directly contradict predictions) are also determined by deduction from the hypotheses.
I don't think that last part is really too different from what you were meaning to say.

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bluegenes
Member (Idle past 2477 days)
Posts: 3119
From: U.K.
Joined: 01-24-2007


Message 72 of 120 (672518)
09-09-2012 2:46 AM
Reply to: Message 71 by nwr
09-08-2012 11:43 PM


Re: Before Abductive, Inductive, or Deductive reasoning ...
nwr writes:
Philosophers (from whom induction and abduction theses come), see observations as abstract proposition.
When you say philosophers, do you mean "all philosophers"?
When a philosopher or a scientist claims that science uses those forms of reasoning, they do so based on observation. Philosophers have merely defined the forms of reasoning used and given them names. Scientists (and laypeople) were reasoning in these ways before the definitions were given. Humans are obliged to use inductive and abductive reasoning when exploring the unknown. We all do it regularly.
nwr writes:
I see a scientific theory as what connects those abstract propositions to reality. The theory is prerequisite to being able to make the observations from which the theory is allegedly induced or abduced.
I see observation as what connects a scientific theory to reality.
You can't hypothesise anything about anything if you are a brain in a void and have never observed anything.
Science is based on both observation and reasoning. An observation based hypothesis, theory or law can certainly guide you to new observations, if that's what you mean. If it predicted the existence of something, it might lead you to look for it, as with physicists searching for direct evidence of the Higgs boson or dark matter, and biologists searching for fish/amphibian transitionals.

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 Message 71 by nwr, posted 09-08-2012 11:43 PM nwr has replied

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 Message 77 by nwr, posted 09-09-2012 3:49 PM bluegenes has replied

  
bluegenes
Member (Idle past 2477 days)
Posts: 3119
From: U.K.
Joined: 01-24-2007


Message 83 of 120 (672608)
09-09-2012 9:40 PM
Reply to: Message 77 by nwr
09-09-2012 3:49 PM


Re: Before Abductive, Inductive, or Deductive reasoning ...
How does the post I'm replying to support the view that you seemed to express in the earlier post I replied to:
nwr writes:
I see a scientific theory as what connects those abstract propositions to reality. The theory is prerequisite to being able to make the observations from which the theory is allegedly induced or abduced.
Do all theories have to be something like dyitherdils explain ptoifyrogiths, because they can't initially involve anything concrete in the real world which we've observed? This must presumably be the case if they are prerequisites for observations.

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bluegenes
Member (Idle past 2477 days)
Posts: 3119
From: U.K.
Joined: 01-24-2007


Message 98 of 120 (672803)
09-11-2012 1:20 PM
Reply to: Message 95 by RAZD
09-11-2012 8:59 AM


Re: still a falsified and in need of modification hypothesis ...
RAZD writes:
It is highly likely that the original form of this painting was created by humans due to the style and technology that would be needed to produce it in the form shown.
Highly likely? Highly likely! A probability estimate without maths? Good. I agree. Humans are the only known source of paintings of such technology and style. Very reasonable.
Now, we didn't need to falsify all other hypotheses in order to reach that inference to the best explanation, did we? We didn't have to show that aliens hadn't visited the planet and imitated our art, or that we haven't somehow missed discovering another very rare and shy intelligent creature from our own life system, or that the fairies hadn't decided to play tricks on us.
Why? Because those hypotheses have no support.
Edited by bluegenes, : No reason given.

This message is a reply to:
 Message 95 by RAZD, posted 09-11-2012 8:59 AM RAZD has replied

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 Message 99 by RAZD, posted 09-11-2012 6:43 PM bluegenes has replied

  
bluegenes
Member (Idle past 2477 days)
Posts: 3119
From: U.K.
Joined: 01-24-2007


(2)
Message 101 of 120 (672871)
09-12-2012 2:56 AM
Reply to: Message 99 by RAZD
09-11-2012 6:43 PM


Dismissal of unsupported alternatives.
RAZD writes:
Yes, I put that in there just for you.
Cheers! And I hope you've taken on board the point about not having to falsify unsupported alternative hypotheses, as well. When we consider the painting Straggler linked to, no amount of unsupported alternative suggestions will weaken the inference to the best explanation.
With cave paintings, it's the same. BTW, elephants seem to be tools used by us to reproduce paintings, rather than actual painters, but the apes could well be real painters if they show signs of producing things that relate in some way to the world around them, rather than just random splotches. So I agree that they're probably a good falsification of a literal "all (artistic) paintings are made by humans."
The easiest way to adjust the hypothesis is by assessing the limitations of apes even when the right tools and materials are placed in their hands. Then considering what they could do without our help.
So, I think the archaeologists and anthropologists are working on a very strong theory when they attribute all ancient cave paintings to us, although "us" could include ancestor and ancestor/relatives going quite far back.
So:
P1: Humans make paintings in which literal representations of things can be recognised.
P2: No other beings are known to do this.
C: All such paintings found on this planet can be attributed to humans with a high level of confidence.
That covers anything from the cave paintings to anonymous efforts like Straggler's.
To relate that to this thread, we can never (formally) establish such things without using both inductive/abductive reasoning and deductive reasoning. Of course, informally, most people would look at Straggler's painting, and the brain goes "looks like a duck, quacks like a duck, it's a duck"; with "human painting" as the duck. Abductions are often treated as facts when they're strong.
So, we can all see the mistake that some creationists make when they demand literal proof for something that is a "best current explanation", not a purely deductively reasoned fact.

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 Message 99 by RAZD, posted 09-11-2012 6:43 PM RAZD has seen this message but not replied

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bluegenes
Member (Idle past 2477 days)
Posts: 3119
From: U.K.
Joined: 01-24-2007


Message 115 of 120 (673331)
09-18-2012 3:19 PM
Reply to: Message 113 by Hawkins
09-18-2012 2:50 PM


Do you understand what this thread's about?
Hawkins writes:
Now are you going to discuss the matter honestly ? That's question for yourself to answer! On the other hand, the discussion continue if you honestly keep throwing fallacies after fallacies.
The first and foremost answer honestly that where the above highlighted statement is a fallacy or not, YES or NO!
Perhaps he knows the difference between abductive reasoning and deductive proofs. Perhaps he understands science, and the subject of this thread.
Do you understand why it is wrong to ask for deductive proofs of scientific theories? Do you understand the subject of this thread?

This message is a reply to:
 Message 113 by Hawkins, posted 09-18-2012 2:50 PM Hawkins has replied

Replies to this message:
 Message 116 by Hawkins, posted 09-18-2012 3:51 PM bluegenes has not replied

  
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