Forwarded with permission -- Charlie is the Chair of the Philosophy
Department at Auburn; and a helluva chef-du-cajun.

---------- Forwarded message ----------
Hello, Bill!  I apologize for taking so long to get back to your
question on Peirce.  I've been wrestling with several plagues of
bureaucracy at once and was almost done in a couple of times.

What I say about Peirce's abduction carries no weight beyond the
phosphors on your monitor's screen, but this is how I understand
it and how I try to explain it to my classes.  The diagrams down
below may help -- at least the students think they do.

The first diagram starts off the scientific method processes of
describing factual experience to get data descriptions.  Then the
data are ordered in various ways as bases for inducing empirical
generalizations.  So much for the first diagram, which takes us
only as far as the old descriptive sciences (as soon as we add
the generalizations).

|||||              ________________               _________________      /
||E||              |              |               |               |    / d.
||X|| description  | D:  Data     |  structuring  | D':  Data as  |  / n
||P|---------------|              |---------------|               |/ I
||E|| perception   | Descriptions |  classifying  |   Organized   |
||R||              |______________|   measuring   |_______________|
||I||                                    etc.
||E||
||N||
||C||
||E||
|||||

Now, I've contracted the items of the first diagram into the second
diagram in order to work in abduction.  The most common form of the
inference is the one that gets us to hypotheses, and the more common
of those routes is the one from generalizations.  Generalizations,
as I'm using the term here, refer to observable objects and predicate
observable properties.  Hypotheses give 'underlying' explanations by
reference to unobservable entities (electrons, quarks) or predicating
unobservable properties (spin, charm).  The abductive inference, which
is sometimes called "conversion of deduction," is the inference (or
intuition or positing or ...) of a set of explanatory conditions from
which the generalization(s) in question can be deduced.  Kepler's
laws of planatary motion are generalizations from (mostly) Brahe's
data, and Newton's laws (hypotheses really) are abductions from the
laws of planatary motion and other generalizations.  Reciprocally,
Kepler's laws are deducible from Newton's.  Occasionally, one might
hit upon an hypothesis abductively from the ordered data (D'), which
seems to have been what Comte had in mind in his exposition of the
scientific method.  He tossed out induction as unreliable, at which
point he and J. S. Mill parted company for the second time -- the
other being when Comte excluded psychology from science.

|||||                                                    ------------
|||||                           _ _ _ _ _ _ _ _ _ _ _ _ | Hypothesis |
|||||                         / Abd.                   / ------------
|||||                       /                        / d.
|||||                     /     ----------------   / b
|||||                   /     /| Generalization |/ A
|||||      ---       ----   /   ----------------
|(((------| D |-----| D' |/
|Abd|      ---       ----
|||||
|||||

There is a wholly different form of abduction (or so it seems to me)
that Peirce uses in his phaneroscopy/phenomenology, and I have that
pictured over on the left side of the second diagram.  Here, he is
trying to get through phenomenal experience to an underlying reality.
A quotation from v. VI of the collected works sets the stage:

  "All our knowledge may be said to rest upon _observed_fact_.  It is
true that there are psychological states which antecede our observing
facts as such.  Thus, it is a fact that I see an inkstand before me;
but before I can say that I am obliged to have impressions of sense into
which no idea of an inkstand, or of any seperate object, or of an 'I,'
or of seeing, enter at all; and it is true that my judging that I see an
inkstand before me is a product of mental operations upon these
impressions of sense.
  "I call all such inference by the peculiar name, _abduction_, because
its legitimacy depends upon altogether different principles from those
of other kinds of inference."

The foregoing is connected with a passage in v. V, in which he says:

  "Abductive inference shades into perceptual judgment without any
sharp line of demarcation between them....On its side, the perceptive
judgment is the result of a process, although of a process not
sufficiently conscious to be controlled, or, to state it more truly, not
controllable and therefore not fully conscious.  If we were to subject
this subconscious process to logical analysis, we should find that it
terminated in what analysis would represent as an abductive inference,
resting on the result of a similar process which a similar logical
analysis would represent to be terminated by a similar abductive
inference, and so on _ad_infinitum_.  The analysis would be precisely
analogous to that which the sophism of Achilles and the Tortoise applies
to the chase of the Tortoise by Achilles, and it would fail to represent
the real process for the same reason.  Namely, just as Achilles does not
have to make the series of distince endeavours which he is represented as
making, so this process of forming the perceptual judgment, because it is
subconscious and so not amenable to logical criticism, does not have to
make separate acts of inference, but performs its act in one continuous
process."

Each "(" at the left of my diagram represents an abductive inference.
What Peirce seems to be trying to do here is to burrow through Kant's &
phenomenalism's perceptual limit -- that veil of Maya -- in order to
_claim_, at any rate, to have reached real external things.  But Peirce
calls those distinctively different kinds of inference, depicted at the
opposite ends of my second diagram, by the same name.  It's not a big
surprise that lots of folks aren't sure what abduction is, is it?

Glad to see that Jamie's still kicking.  Have you checked his web site
at Brown lately to see what's new?

Hope all's well with you and that you're getting some R&R from school.

Cheers!
Charlie