By whom?
From the Wikipedia article you linked (emphasis mine):
Abductive reasoning allows inferring a as an explanation of b. As a result of this inference, abduction allows the precondition a to be abducted from the consequence b. Deductive reasoning and abductive reasoning thus differ in which end, left or right, of the proposition “a entails b” serves as conclusion.
As such, abduction is formally equivalent to the logical fallacy of affirming the consequent (or post hoc ergo propter hoc) because of multiple possible explanations for b.
Maybe you can clear up for me why this article you linked seems to be saying abduction is formally equivalent to fallacious reasoning?
No, as one of my replies above already clarified. Hypothesis-driven research is best modeled by the logical form modus tollens: if P, then Q; ~Q, therefore ~P. We run our hypotheses at nature, wait for her to reply, and then modify our theories, P, in light of disconfirming evidence (~Q).
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And this is very close to @Rumraket’s reasoning, which is not affirming the consequent.
And as other have pointed out, the reason this lends support to CD is IBE, or (I’ll add) a Bayesian analysis. CD makes precise and quantitative predictions about the data, predictions that other hypotheses do not make. These predictions fit very well with patterns we see in the data. That ends up being very strong evidence for CD.
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Typically, those who consciously name their inferences “abductive” (e.g., classically, Peirce), carefully distinguish their relative logical strength from deductive inferences. Abduction is necessarily weaker.
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I don’t believe that’s true. His failure to understand science is quite different from and much deeper than that.
If phylogenetic signal, then evolution and common descent.
We predict a phylogenetic signal from evolutionary mechanisms, then measure the phylogenetic signal in the data.
Perhaps you could tell us what ~Q is if P is “Intelligent Design”?
We had a 1000+ long thread where not one Intelligent Design advocate was able to provide such a hypothesis.
You claim IDers use modus tollens, but in practice the logic is actually one of
- if ~P, then Q; therefore P
- if P, then ~Q; Q; therefore ~(if P, then ~Q).
- Q; therefore (if P, then Q)
or, most commonly, - if R, then ~Q; Q; therefore P
See Behe’s testimony in Kitzmiller for examples.
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Neither was the argument I provided. While it may deviate from how science is done in practice (it rarely functions along lines of simple deductive entailment), the argument I stated nevertheless remains valid.
However, I did also go on to state the argument in terms of expectations, which is how the argument for common descent using tree structure in the data actually works.
So far all your objections have been both wrong and a colossal waste of time.
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