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Abductive reasoning

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http://en.wikipedia.org/wiki/Abductive_reasoning

It's a pretty foreign concept I've been introduced to recently, which claims to be the method of reasoning we use to form initial hypotheses. Just wondering if some people with expertise or knowledge in the field of formal reasoning would like to share their opinions.

A brief explanation of its formal nature from Wiki if you're unfamiliar.:

In formal logic, O and E are assumed to be sets of literals. The two conditions for E being an explanation of O according to theory T are formalized as:

http://upload.wikimedia.org/math/0/6/5/065...c5f33172a28.png

is consistent.

Among the possible explanations E satisfying these two conditions, some other condition of minimality is usually imposed to avoid irrelevant facts (not contributing to the entailment of O) being included in the explanations. Abduction is then the process that picks out some member of E. Criteria for picking out a member representing "the best" explanation include the simplicity, the prior probability, or the explanatory power of the explanation.

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  • 2 months later...

Pft, nobody wants to comment?

Well okay, I was observing that in OPAR, while appealing to a form of epistemological certitude, Peikoff used the method of abduction to validate his claim. I haven't re-read it yet, but I think he was claiming it was rather an appeal to induction. I'm speaking about the section where he used the example of a murder trial, which is a classic example of abduction.

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I don't have expertise or knowledge in the field.

Imagining multiple possibilities and then winnowing them down by a process of elimination is deduction. Ensuring all of the possibilities have been considered also requires some form of systematized enumeration such as filling out a multidimensional table, a reliance on deduction. "Abductive reasoning" is only part of a reasoning process because it does not lead to truth, it merely leads to multiple hypotheses. Why do we need a separate word for hypothesizing?

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Why do we need a separate word for hypothesizing?
I believe because abduction refers to an early step in hypothesizing, namely, generating a pile of hypotheses. When you have narrowed down the field to a favored theory (and presumably an alternative) they you would say "I hypothesize that X", which has a more definite commitment to it.
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I believe because abduction refers to an early step in hypothesizing, namely, generating a pile of hypotheses. When you have narrowed down the field to a favored theory (and presumably an alternative) they you would say "I hypothesize that X", which has a more definite commitment to it.

Here is a rather witty essay on C.S.Peirce's approach to hypothesis formulation:

http://www.visual-memory.co.uk/b_resources/abduction.html

Bob Kolker

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Here is a rather witty essay on C.S.Peirce's approach to hypothesis formulation:

http://www.visual-memory.co.uk/b_resources/abduction.html

Bob Kolker

Ok, I've read that (read it again actually. I came across it when the thread was first posted.) Pierce allocates induction to the role of experimenting, observing, verifying an already existing hypotheses. Abduction is not just making a hypotheses, it is forming new knowledge, the hunch which is correct. I think his concept of induction differs from that of Objectivism, and from Peikoff's additional work on induction. What Pierce calls abduction or sometimes retroduction falls under the scope of what is induction according to Peikoff. Pierce made up this word to name a real phenomena because he had a faulty concept of induction.

He also seems to be mixing in some use of the subconscious in a way that reminds me of Malcolm Gladwell's book Blink.

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Peikoff does not engage in abduction in OPAR. Abduction is a method of reasoning based on the false premise, that pragmatists accept, that when you are going to _explain_ something (not prove something or know something with certainty), then there are virtually an unlimited number of possible theories that can explain.

This premise is false because it assumes that the arbitrary is valid, i.e., to make up explanations and hypotheses without any proof or reason. In fact, Peikoff's entire example in OPAR was in part about why this premise is false and why you must reject it, the arbitrary, to be able to reach rational, contextual certainty. The fact that he used the example of a crime, which is common when explaining abduction, is totally non-essential.

Abduction is, as pragmatism is, based on the idea that we cannot really know reality or truth. Abduction does not give you the true explanation, because there is no such thing according to pragmatism. There is, thus, only the "best explanation". But what determines what constitute the best explanation? Not the facts, not reality.

The pragmatists accept a number of criteria because they "work" in the pragmatic sense of the word. That is, they achieve some goal or satisfy some feelings. Peirce thought, for example, that one such criteria is the alleged consensus among scientists, i.e., not the facts of reality but the opinions of some people. See the insane debate about climate change as an example of how this criteria have caused havoc. But every other criteria the pragmatists accept is ultimately justified on the idea that they "work," pragmatically, not necessarily because there is a rational ground for them.

Let me quote from The Philosopher's Toolkit. A Compendium of Philosophical Concepts and Methods by Julian Baggini and Peter S Fosl:

It is easy to see, then, why Peirce's method of abduction is appealing to pragmatists but troubling to realists, who maintain that science discloses the single nature of independent reality. From a pragmatic point of view, the methods of abduction are not based on the supposition that truth about an indenpendent reality can be irrefutable established, but on the idea that we have to make the best of truth that we can, given the limits of evidence and the demands of life. (p. 40.)

I told you this in the chatroom, but maybe you did not pay attention or something.

Anyhow, the conclusion is: Peikoff does not engage in abduction in OPAR and abduction is not a rational method. It is a method based on pragmatism.

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To Knast,

I'm not seeing how Abduction is based on Pragmatism here. Usually abduction is defended by scientific realists, not the anti-realists (i.e, scientific pragmatists). Do you care to make more than assertions here? Such extraordinary claims may be true, but they require extraordinary evidence. That C.S Peirce was a pragmatist doesn't mean we have to reject what he said on everything. That I have problems with Boole, Frege, Russell and Whitehead doesn't mean that I have to completely reject all matters of modern logic.

To Grames,

I think I agree that abduction, within Objectivism, could just be subsumed under a fully developed theory of induction. Hopefully one day we will see that.

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What we have here are basically three questions:

1. What is the relationship between Pragmatism and abduction?

2. What is the relationship between scientific realism and abduction?

3. Can abduction be valid? Can it be justified on rational grounds?

I will let C S Peirce, the founder of Pragmatism and the original proponent of abduction, answer the first question:

Admitting, then, that the question of Pragmatism is the question of Abduction, let us consider it under that form. What is good abduction? What should an explanatory hypothesis be to be worthy to rank as a hypothesis? Of course, it must explain the facts. But what other conditions ought it to fulfill to be good? The question of the goodness of anything is whether that thing fulfills its end. What, then, is the end of an explanatory hypothesis? Its end is, through subjection to the test of experiment, to lead to the avoidance of all surprise and to the establishment of a habit of positive expectation that shall not be disappointed. Any hypothesis, therefore, may be admissible, in the absence of any special reasons to the contrary, provided it be capable of experimental verification, and only insofar as it is capable of such verification. This is approximately the doctrine of pragmatism. But just here a broad question opens out before us. What are we to understand by experimental verification? The answer to that involves the whole logic of induction.

Source: http://www.textlog.de/7658.html

For an elaboration see, for instance, here: http://books.google.com/books?id=W5JTAizNQ...tism&f=true

As for the second question, I have noticed that scientific realists use "the argument to the best explanation", i.e., abduction, to argue for realism. But it is one thing to use this argument for this purpose and to use it to come up with good scientific hypotheses as such. It is also one thing to use it within the originally Pragmatic context and another thing to use it outside of that context.

To defend scientific realism on the grounds of abduction is, within the context of modern philosophy, a bad idea because, among other things, the invoking of the arbitrary is an accepted practice among the moderns. This means, within in the modern context, that abduction will never give us "the truth", but only "the best truth" available. Something pragmatic minded people might settle for, but proper realists would not. Also, the fantastic "arguments" of many anti-realists against realism indicates how dangerous it is.

Now, is there a sense in which abduction could be considered valid? Yes. If you define abduction as a method of coming up with good hypotheses and nothing else, then within the context of a rational philosophy, i.e., a philosophy that, among other things, do not allow for the arbitrary, i.e., Objectivism, then it might be viewed as something entirely rational and good. Objectivism, obviously, has nothing against abduction, i.e., the creation of good hypotheses.

I would like to add that from what I have read, Peikoff does give a good explanation for why abduction, in this sense, works. His explanation is that we, as scientists, do not start out as babies. We have an enormous context of knowledge, consisting of many first level generalizations. This is what guides us when we form our hypotheses and design our experiments. I quote from David Harriman's essay "Induction and Experiment Method":

It is instructive to note the experiments that Galileo did not perform. He saw no need to vary every known property of the pendulum and look for a possible effect on the period. For example, he did not systematically vary the color, temperature, or smell of the pendulum bob; he did not investigate whether it made a difference if the pendulum arm is made of cotton twine or silk thread. Based on everyday observations, he had a vast prescientific context of knowledge that was sufficient to eliminate such factors as irrelevant. To call such knowledge “prescientific” is not to cast doubt on its objectivity; such lower-level generalizations are acquired by the implicit use of the same methods that the scientist uses deliberately and systematically, and they are equally valid. Given such a context, Galileo quickly concluded that the period of a pendulum depends only upon its length.

http://www.theobjectivestandard.com/issues...ntal-method.asp

But induction is, according to the moderns, at best not reliable and at worst invalid. And some moderns use the very fact that we have this context of knowledge, as an argument against induction. Thus the only thing that could ever make abduction, the creation of good hypotheses, valid is rejected by the modern mainstream philosophers. Thus if you want abduction to make sense, to work, you can only make it happen within the context of a rational philosophy, i.e., Objectivism.

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  • 4 weeks later...
What we have here are basically three questions:

...

3. Can abduction be valid? Can it be justified on rational grounds?

Sometimes the facts are such that there is some, but not much, evidence in favor of a proposition and nothing known that contradicts it.

If the proposition explains a wide variety of phenomena, there is value in adopting it AS IF it were true--just to see what facts it leads us to.

In that context, hypotheses have enormous INSTRUMENTAL value, i.e. as part of a method for acquiring more knowledge.

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I believe because abduction refers to an early step in hypothesizing, namely, generating a pile of hypotheses. When you have narrowed down the field to a favored theory (and presumably an alternative) they you would say "I hypothesize that X", which has a more definite commitment to it.

I haven't seen that concept of "hypothesis" used anywhere else. I'd like to hear more about it.

I've always heard "hypothesis" used more generally, along the lines of "testable proposition held with uncertainty"

This is distinct from "postulate", which is a "proposition taken as a starting point, as if it were true, for the sake of demonstrating other propositions"

Sometimes, the same proposition serves both functions. For example, the invariance of the speed of light is a hypothesis insofar as it makes predictions. But it's a postulate in the sense of being a foundational proposition in the theory of Special Relativity.

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