[lit-ideas] Re: Is 'All men are mortal' unscientific?
- From: Donal McEvoy <donalmcevoyuk@xxxxxxxxxxx>
- To: lit-ideas@xxxxxxxxxxxxx
- Date: Wed, 12 Mar 2008 22:51:28 +0000 (GMT)
This derives from the following url:-
http://www.nst.com.my/Current_News/NST/Tuesday/Features/20080310170238/Article/indexpull_html
> ALBERT LIM KOK HOOI on falsifiability:
>
> > The statement “all men are immortal” is a scientific statement,
> > whether or not it is true or false. The moment we find a dead human, we
> > have proven that the statement is false. Nevertheless it is a scientific
> > theory. It is framed in such a way that there is a way to prove it false.
> > In this case, the proof that it is false is easy, i.e. find a dead man and
> > the assertion that “all men are immortal”
> > is no longer true.
As far as I understand, the above is a correct reflection of Popper's position.
However, consider:-
> > The statement “all men are mortal”, on the other hand, is not a
> > scientific statement. It is not potentially falsifiable (i.e. have you
> > found a man who did not die?). No finite amount of observations could ever
> > > > demonstrate its falsehood.
The position here is more complex and Popper discusses it, for example, in his
_Schilpp_ volumes at pp.992-993 in reply to Quine.
Having argued that every example of a dead human is not inductive support for
the conclusion that all humans will die (any more than it is support for the
conclusion that all things that die are humans), Popper writes:-
"Quine also discusses "All men are mortal", but he takes "x is mortal" to mean
"there is a time t such that x dies at t". This is how I myself have analysed
some (but not all) "all-and-some statements"..." [in LDF, see n.*2 on
p.193].."that is, as of the form (x)(Ey)F(x,y). I have also pointed out not
only the consequences drawn by Quine but also how mistaken it would be to
assume (as Hempel did at the time I wrote this criticism, following up a
somewhat carelessly formulated remark of mine) that statements of this kind are
never falsifiable. For example, that statements "All brothers have sisters" and
"All primes are twin primes" can both falsified. The question - as I noted -
depends upon whether F does or does not impose a finite limit upon the range of
the y relative to every given x."
Quine had written at the very end of his paper (p.219):-
"But now let us move up to the next grade of complexity: 'All men are mortal'.
This is logically more complex than 'All ravens are black', if we analyse
morality itself into an existential quantification: 'x is mortal' means '(Et)(x
dies at t)'. Just as an unblack raven is what it takes to refute 'All ravens
are black', so an immortal man is what it takes to refute 'All men are mortal';
but the problem of spotting and certifying an immortal man is a problem of a
different order from that of spotting and certifying an unblack raven. For
'Jones is immortal' is itself univeral like 'All ravens are black'; it says
that all future times are times in Jone's life.
The fact of the matter is that a law with the complexity of 'All men
are mortal' admits of no direct evidence for or against: no direct refutation
and no direct demonstration . When we reach even this moderate level of
complexity, any implication of verifiable or falsifiable consequences must
depend under collaboration. Sentences governed by multiple mixed quantifiers
may, when taken in conjunction, imply some singular sentences, even though they
imply no such sentences when taken separately.
Suddenly our topic is doubly complex. Our laws or hypotheses are
neither simply universal nor simply existential, but multiply quantified; and
we are considering what observable consequences these laws imply not law by
law, but conjointly. Our topic, in short, is now the more or less comprehensive
theory rather than the lone hypothesis. At this level is there still any good
reason for Sir Karl's negative bias, his negative doctrine of evidence? There
is indeed, and it is essentially different now from what it was in the case of
'All ravens are black'. It is that we think of theories as conjunctions of laws
and not as alternations of laws. Logically, duality is present as usual; laws
taken in conjunction may imply singular consequences and laws taken in
alternation may be implied by singular conditions. But a scientific theory
consists of laws in conjunction, not alternation; and its evidence lies in the
singular consequences. Failure of such a
consequence refutes the theory, while verification of such a consequence is as
may be."
Popper in his reply writes:- "With Quine's final remarks I agree completely."
That settles it then.
Donal
visiting www.andreas.com/faq-lit-ideas.html and leaving a donation, but not
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