Popper's 'Scientific' Irrationalism

Reilly Jones (Reilly@compuserve.com)
Wed, 19 Mar 1997 03:01:21 -0500

Lee Daniel Crocker wrote 3/17/97: <This is insufferable misinterpretation
of Popper, and with no excuse given other than Stove's own emotional
discomfort with carefully reasoned ideas.... Mr. Stove seems uncomfortable
with the obvious fact that expanding knowledge implies expanding
ignorance.... Mr. Stove's discomfort with "conjectural knowledge" is
merely cowardice: he doesn't want to admit that every act taken by every
human being is a gamble on
the efficacy of what we call knowledge. He seems dismayed by that rather
than enlivened and freed. That's /his/ failure, not Popper's.>

Oh my. Armchair pschoanalytical attributions of emotional defects to other
individuals' reasoning processes does not make those reasoning processes
irrational. The armchair stance itself is irrational; it is not reasoning,
it is political invective. Popper's "carefully reasoned ideas," as you put
it, were in fact, sloppily executed attempts to unsuccessfully deduce his
way out of a wet paper bag. See the fatal critique below.

Guru George wrote 3/17/97: <Sorry to disagree with you Reilly, but I have
to say that Stove's critique of Popper is complete bollocks - much as I
enjoy Stove's acidic style. The point of 'falsifiability' is this: if you
are serious about using experience to test theory then the only way you can
*logically* do so is deductively: you deduce empirical consequences from a
theory, and if those experiences don't pan out, then the theory logically
*must* be false.>

So you give Stove an A for style, and an F for content. Does that average
out to a C? ;) See the fatal critique below.

Guru: <But there is no such thing as a *logic* of induction: there is no
logical *necessity* to induction, no logical 'must', like you get in
deduction: this is what Hume showed.>

Stove reportedly held Hume in the highest regard, but this did not prevent
him from correcting Hume's 'perfectionistic' errors. I have a strong
hunch, but I am not certain <g>, that your concerns are addressed by Stove
in his technical works "Rationality of Induction" (1986), and "Probability
and Hume's Inductive Skepticism" (1973).

Stove's point about the efficacy of the cumulative results of induction,
can be seen in a common-sensical way if you picture yourself as a scientist
seeking grant money from the government or private sources to do scientific
experiments. It is commonplace to obtain funding for an experiment seeking
to verify predictions of a highly regarded (meaning politically sanctioned)
theory, or to perform duplicate experiments to immediately verify previous
highly regarded experimental results. But it is hard to obtain funding for
doing experiments on 'crackpot' theories (where did the authority to label
them 'crackpot' come from?), and it becomes exceedingly difficult to fund
the duplication of well-established experimental results more than a few

Now, Guru George says that "Popper's idea is that we ought to test our
ideas to destruction." But this is clearly irrational on the face of it.
No scientist, and no funding agency, is going to indefinitely work on
duplicating the same experiment over and over and over, "to destruction."
Scientists working in the real world don't want to waste their lives
increasing the cumulative inductive probabilities from a very high
percentage to an infinitesimally higher percentage; nor do agencies with
money to spend on science. This is the real rational world, not Popper's
irrational critical-unto-destruction world.

All right, out of the purest, most unselfish, highest altruistic extropian
motives, I will, as a public service to all interested newbies on the list,
repost the fatal criticism of Popper's falsifiability principle.


>From "PHIL: Questioning Popperianism" 3/8/95:

Quotes from Elliott Sober's "Philosophy of Biology" (1993):

"Popper's criterion of falsifiability requires that we be able to single
out a special class of sentences and call them observation sentences. A
proposition is then said to be falsifiable precisely when it is related to
observation sentences in a special way: Proposition P is falsifiable if
and only if P deductively implies at least one observation sentence O. One
problem with Popper's proposal is that it requires that the distinction
between observation statements and other statements be made precise. To
check the statement 'The chicken is dead,' you must know what a chicken is
and what death is. *This problem is sometimes expressed by saying that
observation is theory laden.* Every claim that people make about what
they observe depends for its justification on their possessing prior
information. Popper addresses this problem by saying that what one regards
as an observation statement is a matter of convention. But this solution
will hardly help one tell, in a problematic case, whether a statement is
falsifiable. For Popper's criterion to have some bite, there must be a
nonarbitrary way to distinguish observation sentences from the rest. To
date, no one has managed to do this in a satisfactory manner.

The problems with Popper's falsifiability criterion go deeper. First,
there is the so-called tacking problem. Suppose that some proposition S is
falsifiable. It immediately follows that the conjunction of S and any
other proposition N is falsifiable as well. That is, if S makes
predictions that can be checked observationally, so does the conjunction S
& N. This is an embarrassment to Popper's proposal since he wanted that
proposal to separate nonscientific propositions N from properly scientific
propositions S. Presumably, if N is not scientifically respectable,
neither is S & N. The falsifiability criterion does not obey this
plausible requirement.

Another problem with Popper's proposal is that it has peculiar
implications about the relation of a proposition to its negation. Consider
a statement of the form 'All As are B.' Popper judges this statement
falsifiable since it would be falsified by observing a single A that fails
to be B. But now consider the negation of the generalization-the statement
that say 'There exists an object that is both A and not-B.' This statement
is not falsifiable; no single observed object or finite collection of them
can falsify this existence claim. So the generalization is falsifiable,
though its negation is not. But this is very odd-presumably, if a
statement is 'scientific,' so is its negation. *This suggests that
falsifiability is not a good criterion for being scientific.*

Still another problem with Popper's proposal is that most theoretical
statements in science do not, all by themselves, make predictions about
what can be checked observationally. Theories make testable predictions
only when they are conjoined with auxiliary assumptions. Typically, T does
not deductively imply O; rather, it is T & A that deductively implies O
(here, T is a theory, O is an observation statement, and A is a set of
auxiliary assumptions). This idea is sometimes called Duhem's Thesis...

The final problem with Popper's proposal is that it entails that
probability statements in science are unfalsifiable. Consider the
statement that a coin is fair-that its probability of landing heads when
tossed is 0.5. ...It is possible for a fair coin to land heads on all ten
tosses, to land heads on nine and tails on one, and so on. Probability
statements are not falsifiable in Popper's sense. In fact, something like
the Likelihood Principle is what Popper himself adopted when he recognized
that probability statements are not falsifiable.

Popper held that there is an asymmetry between falsification and
verification. A vestige of Popper's asymmetry can be restored if we
include the premiss that the auxiliary assumptions (A) are true:

Falsification Verification
If T & A, then O If T & A, then O
not-O O
-------- --------
not-T T
deductively valid deductively invalid

Although we now seem to have a difference between verification and
falsification, it is important to notice that the argument falsifying T
requires that we be able to assert that the auxiliary assumptions A are
true. Auxiliary assumptions are often highly theoretical; if we can't
verify A, we will not be able to falsify T by using the deductively valid
argument form just described. In the last pair of displayed arguments, one
is deductively valid and the other is not. However, this does nothing to
support Popper's asymmetry thesis. In fact, we should draw precisely the
opposite conclusion: The left-hand argument suggests that if we cannot
verify theoretical statements, then we cannot falsify them either.

One problem with Popper's asymmetry thesis is that it equates what can be
known with what can be deduced validly from observation statements.
However, science often makes use of nondeductive argumentation, in which
the conclusion is said to be rendered plausible or to be well supported by
the premisses. In such arguments, the premisses do not absolutely
guarantee that the conclusion must be true.

On the face of it, vulnerability appears to be a defect, not a virtue.
Why is it desirable that the hypotheses we believe should be refutable?
Wouldn't science be more secure if it were invulnerable to empirical
disconfirmation? The Likelihood Principle helps answer these questions. A
consequence of this principle is that if O favors H1 over H2, then not-O
would favor H2 over H1. This is because if P(O/H1) > P(O/H2), then
P(not-O/H1) < P(not-O/H1). We want our beliefs to be supported by
observational evidence. For this to be possible, they must be vulnerable;
there must be possible observations that would count against them. This
requirement is not a vestige of the discredited falsifiability criterion.
It flows from the Likelihood Principle itself."


>From "PHIL: Questioning Popperianism" 3/10/95:

My commentary on Sober's quotes: I agree with Sober that falsifiability is
not a criterion for a scientific proposition, his points are valid.

His points about there being no "nonarbitrary way to distinguish
observation sentences from the rest" and "observation is theory laden" deal
with semantic and logical limitations inherent in our biological nature. I
think that deductive logic and mathematics are wonderful tools for
producing truth. The truth they produce, however, is bounded within the
axiomatic system chosen. Popper's desire to produce truth by limiting it
to deductive logical observation statements that can be falsified is a
narrow view typical of any evolving system of science approaching nullity
(the only end result of criticism or skepticism). The tacking problem, the
negation problem, the auxiliary statements problem are all related to this
narrowness of view that plagues deduction.

The point about probability statements not being falsifiable addresses
induction problems, such as Hume's critique about the deductive disconnect
between cause and effect. Any time probabilty is used anywhere, for
anything, it is an announcement of ignorance of what will happen next,
meaning an ignorance of causes. Probability statements are maps of
objective truth, generalizations open to interpretations from whatever
theory you subscribe to at the moment that satisfies your needs.

To me, verifiability is every bit as important as falsifiability is. I
agree that where possible, we want our beliefs to be supported by
vulnerable observational evidence. Experimental evidence, though, begins
with theory which is wide-open, and ends with relative boundaries being
drawn around events and objects that constitute what the experiment is, and
what the evidence is. The only real event and object that can be described
in an absolute sense, is the whole universe. Since we can't do this, we
fall back on utility, we describe each event and object as best fits our
needs of the moment while aiming at truth. In science, we try to get as
much consensual agreement on these relative boundaries as possible, so that
our experiments can be repeated. Obviously, no experiment or event is ever
exactly duplicated. All events are historical, unique and irreversible,
but many scientifically agreed on events are similar enough to suit our
needs of the moment. Verifiability occurs when we bring scientific
knowledge to bear on our life through technology. Science is verified
through practical usefulness in hard material reality.

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