List, Gary,
The question was, would I be inclined to take the leading principle of
deduction to be logical (or formal), and the leading principles of
induction and abduction to be factual (or material). Already I need to
revise my answer a little. A deduction's leading principle can be
logical or factual.
Anyway, here's how I replied, with some formatting revisions and some
added sentences that don't reflect what I said just above.
QUOTE (of myself):
Good question. I don't know!
I'm inclined to think that for abduction and induction they would be
factual principles, to the extent that one can call an evaluation of
plausibility or of verisimilitude factual. At any rate they wouldn't
be formal, I think.
(Note that herein "C" and "A" are not universally quantified
proposition variables, but dummy letter (or veiled constants);
pretend that the leading principle is about two specific statements.)
*C.**
**If A then C.**
**Ergo* (plausibly) *A.*
*Leading principle:**
**Every case of {C & if A then C} is* (plausibly) *a case of A.*
But then adding the leading principle as a premiss, and being
consistent in keeping or removing parentheses around the word
"plausibly" below, results in a deductive form:
*C.**
**If A then C.* (If A were true, then C would naturally follow.)
*Every case of **{**C & if A then C} is plausibly a case of A.* (Was
the leading principle.)
*Ergo plausibly A.*
At this point one has moved the real action of the abductive
inference into the premisses and made the inference look deductive.
It's fine to make that transformation in order to better understand
what is happening, but it's not the best way to think of abductive
inference in the end, I think. Also, if one takes the parentheses
away from "plausibly", one ends up with an idea of some sort of
plausibility-version of implication in the third premiss. Well, if
there's plausible inference, I guess there should be plausible
implication, and maybe that's something worth thinking about, even
if the last inference schema above isn't the best way to think of
abductive inference.
Tomis Kapitan moves the real abductive action into the premisses and
ends up with an inference that looks deductive (in “Peirce and the
Autonomy of Abductive Inference” (PDF)
http://www.niu.edu/phil/%7Ekapitan/pdf/PeirceandtheAutonomyofAbductiveReasoning1992.pdf
Erkenntnis 37 (1992), pages 1–26, mentioned by Nathan Houser in “The
Scent of Truth” http://www.academia.edu/611929/The_scent_of_truth
(Semiotica 153—1/4 (2005), 455–466)). Kapitan ends up giving up on
the idea of abductive inference as a basic mode of inference on a
par with deduction and induction. His approach also seems to make
one abductive inference into many, in cases where people disagree
howsoever fuzzily how much plausibility, test-worthiness, etc., an
abductive conclusion has.
END QUOTE.
Now, I do think that there are some logical or formal leading principles
for abduction and induction. There is the leading principle that they be
ampliative (i.e., non-deductive); i.e., instances of ampliative
schemata. But these, if they exhibit nothing more than
non-deductiveness, will not assure truth then and there, nor eventually,
but only will promise the opportunity for a truth not already entailed
in the premisses. So there needs to be something more, whether logical
(or formal) or factual (or material), but now I'm thinking that it
doesn't seem quite right to think that further leading principles must
all be factual. If I try to come to a decision now I'll never send this
post!
Best, Ben
On 5/17/2016 4:29 PM, Gary Richmond wrote:
List, Ben,
In a phone conversation with Ben Udell today I happened to mention
Peirce's notion of a "leading principle" which I recall Peirce having
considered important in consideration of the three inference patterns.
Ben did some quick Googling and sent me P's discussion of a leading
principle in Baldwin's Dictionary (I've cut and pasted that entire
entry below my signature for ready reference). I then sent Ben a
message responding to material in the first paragraph of the entry and
a remark Peirce makes near the end of the second (not quoted in my
email to Ben below):
GR to BU: I remember reading this passage several times a few years
ago when I was trying to get a handle on P's notion of a leading
principle. He writes:
It is of the essence of reasoning that the reasoner should proceed,
and should be conscious of proceeding, according to a general habit,
or method, which he holds would either (according to the kind of
reasoning) always lead to the truth, provided the premises were true;
or, consistently adhered to, would eventually approximate
indefinitely to the truth; or would be generally conducive to the
ascertainment of truth, supposing there be any ascertainable truth. (CSP)
So I take this to mean that the leading principle (general habit,
method) which would "always lead to the truth" is that of deduction;
that which "would eventually approximate indefinitely to the truth"
is that of induction; and that which "would be generally conducive to
the ascertainment of truth, supposing there be any ascertainable
truth" would be that of abduction. The first is a "logical" or
"formal" leading principle. The other two are "factual" or "material"
leading principles.
Is that how you read this passage?
Ben's response was so interesting that I asked him if we might take
this discussion on to the list and he agreed (there may be a brief
delay in his responding to this message as he wanted to polish up some
formatting in his original off-list email to me).
Best,
Gary R
http://psychcentral.com/classics/Baldwin/Dictionary/defs/L3defs.htm#Leading%20Principle
*Leading Principle: * Ger. /leitendes Prinzip/ ; Fr. /principe
directeur/ ; Ital. /principio fondamentale/ . It is of the essence of
reasoning that the reasoner should proceed, and should be conscious of
proceeding, according to a general habit, or method, which he holds
would either (according to the kind of reasoning) always lead to the
truth, provided the premises were true; or, consistently adhered to,
would eventually approximate indefinitely to the truth; or would be
generally conducive to the ascertainment of truth, supposing there be
any ascertainable truth. The effect of this habit or method could be
stated in a proposition of which the antecedent should describe all
possible premises upon which it could operate, while the consequent
should describe how the conclusion to which it would lead would be
determinately related to those premises. Such a proposition is called
the 'leading principle' of the reasoning.
Two different reasoners might infer the same conclusion from the same
premises; and yet their proceeding might be governed by habits which
would be formulated in different, or even conflicting, leading
principles. Only that man's reasoning would be good whose leading
principle was true for all possible cases. It is not essential that
the reasoner should have a distinct apprehension of the leading
principle of the habit which governs his reasoning; it is sufficient
that he should be conscious of proceeding according to a general
method, and that he should hold that that method is generally apt to
lead to the truth. He may even conceive himself to be following one
leading principle when, in reality, he is following another, and may
consequently blunder in his conclusion. From the effective leading
principle, together with the premises, the propriety of accepting the
conclusion in such sense as it is accepted follows necessarily in
every case. Suppose that the leading principle involves two
propositions, /L/ and /L'/ , and suppose that there are three
premises, /P/, /P'/, /P''/; and let /C/ signify the acceptance of the
conclusion, as it is accepted, either as true, or as a legitimate
approximation to the truth, or as an assumption conducive to the
ascertainment of the truth. Then, from the five premises /L/, /L'/ ,
/P, P'/, /P''/ , the inference to /C/ would be necessary; but it
would not be so from /L/, /L'/, /P'/, /P''/ alone, for, if it were,
/P/ would not really act as a premise at all. From /P'/ and /P''/ as
the sole premises, /C/ would follow, if the leading principle
consisted of /L/, /L'/, and /P/. Or from the four premises /L'/, /P/,
/P'/, /P''/, the same conclusion would follow if /L/ alone were the
leading principle. What, then, could be the leading principle of the
inference of /C/ from all five propositions /L/, /L'/, /P/, /P'/,
/P''/, taken as premises? It would be something already implied in
those premises; and it might be almost any general proposition so
implied. Leading principles are, therefore, of two classes; and any
leading principle whose truth is implied in the premises of every
inference which it governs is called a 'logical' (or, less
appropriately, a /formal/ ) leading principle; while a leading
principle whose truth is not implied in the premises is called a
'factual' (or /material/ ) leading principle. (C.S.P.
<http://psychcentral.com/classics/Baldwin/Dictionary/defs/colls.htm#csp> )
Gary Richmond
*Gary Richmond
Philosophy and Critical Thinking
Communication Studies
LaGuardia College of the City University of New York
C 745
718 482-5690*
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