[hist-analytic] Metaphysical Positivism v. Critical Rationalism (Jones v. Frederick)

Roger Bishop Jones rbj at rbjones.com
Fri Sep 18 16:36:00 EDT 2009

On Friday 18 September 2009 12:50:46 Baynesr at comcast.net wrote:

> I thought that in view of
> the fact that the topic is rationalism, of a sort, you might be amused by
> the following quote.
>"It may be regarded, afdter a fashion, as a modern fulfillment of Descartes'
> quest for an absolutely certain basis of science; and indeed Carnap's
> theory is reminiscent of Descartes' rationalism in more wayst than one.
> Reichenbach ("Linguistic Empiricism in Germany and the Present State of the
> Problems" in JP. xxxiii, no. 6. March 1936, p.149."

It would be interesting to know which of Carnap's theories he was
talking about.  The Aufbau?

>There was no one who displayed more logical or mathematical rigour at
> philosophy than Reichenbach. No one supported Reichenbach more strongly
> than Reichenbach. In fact, Carnap had to modify some of his views owing to
> Reichenbach just as he had to modify his views in light of Neurath's
> criticisms regarding "protocol" sentences.

Your phrase "had to modify" suggests that he did so reluctantly,
but reverting to a previous topic, it seems to me that he was
always eager to adapt his philosophy as a result of what he
learned from others.

>Just thought you might be amused: Carnap and Descartes; two peas in a pod?
> So much for Hume!

Personally I would not liken Carnap to Descartes, because Carnap,
like Hume and even like Plato, had a better grip on the scope of reason.
If you want an interesting comparison between Carnap and rationalist,
then the comparison with Plato works much better, but I think the
parallel is clearer still between Hume and Plato, and of course,
though Carnap made little of it, Wittgenstein I believe observed
that the things which Carnap thought he had takem from the Tractatus
he could have found in Hume.

Hume's fork, which is "essentially" the same as the analytic/synthetic
which was very important to Carnap, was pretty much the same distinction
as that in Plato between the "real" word of Platonic forms and the
shadowy world of appearances.  They disagree about which of these two
is "real" (or for Hume, factual), but they agree first in drawing a
fundamental distinction on the basis of the subject matter, and
secondly that knowledge is confined to that of platonic forms
(relations between ideas), and that our beliefs about matters of
fact (the world of appearances) are mere opinion
(epistemically unjustified habits for Hume).

So Hume had this extremely positive opinion of deductive methods,
and negative view of induction (or any other way of obtaining
factual conclusions), which seems odd for an empiricist.
With not quite the same scepticism this is echoed in Carnap.
This is why I view Hume and positivism as having been a first
attempt at a synthesis between rationalism and empiricism
(even though one can also see positivism as a specially radical
form of empiricism).
Logical Positivism is another attempt at such a synthesis,
in which necessary/analytic judgements have a greater role
than in Hume as a result of the advances in logic.
The shift from Hume to Carnap is also one from a philosopher
who (despite his scepticism) modelled philosophy on the empirical
(natiural) sciences, to one who modelled philosophy on
demonstrative science, so from this point of view it is a
second attempt at sythesis between rationalism and empiricism.

Metaphysical Positivism is another attempt at finding the
right analysis of the respective roles of deduction and of
empirical observation in the establishment of knowledge.

So far as I understand it, Critical Rationalism, seems to me
a regression to the kind of rationalism of which Descartes is
an example, in which there is no clear conception of the scope
of reason, and hence a tendency to approach by deductive
arguments conclusions which cannot properly be demonstrated.


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