Helmut, List:
I agree that deduction, induction, and abduction (or retroduction)
correspond respectively to necessity (or certainty), probability, and
plausibility. According to Peirce, that is because the nature of the
assurance for each type of argument is respectively of form, of experience,
and of instinct (EP 2:490, 1908). In particular, "By plausibility, I mean
the degree to which a theory ought to recommend itself to our belief
independently of any kind of evidence other than our instinct urging us to
regard it favorably" (CP 8.223, c. 1910).
I suggest that the reason why there is no unique kind of reasoning that
corresponds to possibility is because it is of the same mode as necessity,
as Peirce observes (CP 5.459, EP 2:358, 1905). A proposition that is
possibly true is not necessarily false, and a proposition that is
necessarily true is not possibly false.
As for probability, Peirce carefully distinguishes its objective and
subjective varieties, also referring to the latter as "likelihood."
CSP: By an objective probability I mean one which could be used to
guarantee an insurance company or gamester against loss, because it
expresses the real fact that among occurrences of a certain genus a certain
proportion are of a certain species. Such is the probability of one/six
that a die will turn up any particular face. Such a probability must be
distinguished from a mere likelihood which is nothing better than the
expression of our preconceived ideas. The confusion between those two kinds
of probability is one of the main sources of human errors, especially in
abduction, in which yielding to judgments of likelihood is a fertile source
of waste of time and energy. (CP 6.534, 1901)
CSP: An objective probability is the ratio of frequency of a specific to a
generic event *in the ordinary course of experience*. Of a fact *per se* it
is absurd to speak of objective probability. All that is attainable are
subjective probabilities, or likelihoods, which express nothing but the
conformity of a new suggestion to our prepossessions; and these are the
source of most of the errors into which man falls, and of all the worst of
them. (CP 2.777, 1902)
CSP: I am one of those who maintain that a probability must be a matter of
positive knowledge, or confess itself a nullity. ... It is of the extremest
importance to distinguish entirely different qualities commonly confounded
under the name of probability. One of these, which I term "likelihood" is
the most deceptive thing in the world, being nothing but the degree of
conformity of a proposition to our preconceived ideas. (CP 2.101, 1902)
Accordingly, it seems to me that modern conspiracy theories are based more
on *likelihood *(conforming to preconceptions) than on *plausibility *(being
regarded favorably by instinct). After all, for Peirce it is the latter
that makes a *scientific *hypothesis worthy of further investigation. "[I]t
is the simpler hypothesis in the sense of the more facile and natural, the
one that instinct suggests, that must be preferred; for the reason that
unless man have a natural bent in accordance with nature's, he has no
chance of understanding nature, at all" (CP 6.477, EP 2:444, 1908).
I also disagree that plausibility somehow corresponds to the irrational
numbers. Being indeed gradual/continuous, rather than pseudo-continuous
like the real numbers (CP 6.176, 1908), it is more amenable to
*qualitative *characterization than to *quantitative *measurement. "[T]his
acceptance ranges, in different cases,--and reasonably so,--from a mere
expression of it in the interrogative mood, as a question meriting
attention and reply, up through all appraisals of Plausibility, to
uncontrollable inclination to believe" (CP 6.469, EP 2:441, 1908).
Regards,
Jon Alan Schmidt - Olathe, Kansas, USA
Structural Engineer, Synechist Philosopher, Lutheran Christian
www.LinkedIn.com/in/JonAlanSchmidt - twitter.com/JonAlanSchmidt
On Thu, Sep 30, 2021 at 12:06 PM Helmut Raulien <h.raul...@gmx.de> wrote:
Supplement: Modern conspiracy theories are based on plausibility. In our
western cultures, many important things too are based merely on
plausibility, e.g. the value of money, the leading position of a manager,
close to everything. No big difference from how things work at remote
places in Africa.
List,
There are are four traits of likeliness: Necessity, probability,
possibility, plausibility, but I think, that possibility is special: It
does not have a value, and it goes with the other three, but merely with
plausibility it goes hand in hand. With the other two it is for granted. So
I propose "necessity-probabiliy-plausibility", assigned to the three kinds
of conclusion:
Deduction: It produces necessity, the value of necessity is a binary
integer-number- value, so not continuous: Yes or no, or 1 or 0. It is
comprehensible, therefore objective.
Induction: It produces a probability, its value always is a quotient, so
of a rational number, so not continuous. An induction is comprehensible,
therefore objective. But it may be executed by an individual who knows
less, more, and/or different things than another individual, thus having an
individual result, so it is subjective as well.
Abduction: It produces a hypothesis, a subjective possibility, whose value
plausibility can only be estimated. The value plausibility nevertheless is
gradual, continuous, so of irrational number. With abduction, this special
kind of -in this case- valued possibility, plausibility, is only subjective.
I think it is important to understand, that hypotheses and their value of
plausibility are merely subjective. The subject of the plausibility may,
besides an individual, be a culture too. In former times and cultures, as
well as in some contemporary African cultures, e.g. the reality of
witchcraft was and sadly is highly plausible, other than in our western
culture(s). Not so long ago, in Germany extremely murderous hypotheses were
plausible. Plausibility should be handled carefully, with a fire tongs.
Best,
Helmut
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