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Date:         Thu, 7 Jan 1993 15:30:15 EST
From:         "Bruce E. Nevin" <bnevin@CCB.BBN.COM>
Subject:      hypotheses non fingo

[From: Bruce Nevin (Thu 930107 15:28:31)]

Daughter:   Daddy, what is an instinct?
Father:  An instinct, my dear, is an explanatory principle.
D: But what does it explain?
F: Anything--almost anything at all.  Anything you want it to
   explain.
D: Don't be silly.  It doesn't explain gravity.
F: No.  But that is because nobody wants "instinct" to explain
   gravity.  If they did, it would explain it.  We could simply
   say that the moon has an instinct whose strength varies
   inversely as the square of the distance . . .
D: But that's nonsense, Daddy.
F: Yes, surely.  But it was you who mentioned "instinct," not I.
D: All right--but then what does explain gravity?
F: Nothing, my dear, because gravity is an explanatory principle.
D: Oh.

D: Do you mean that you cannot use one explanatory principle to
   explain another?  Never?
F: Hmm . . . hardly ever.  That is what Newton meant when he
   said, "hypotheses non fingo."
D: And what does that mean?  Please.
F: Well, you know what "hypotheses" are.  Any statement linking
   together two descriptive statements is an hypothesis.  If you
   say that there was a full moon on February 1st and another on
   March 1st; and then you link these two observations together
   in any way, the statement which links them is an hypothesis.
D: Yes--and i know what _non_ means.  But what's _fingo_?
F: Well--_fingo_ is a late latin word for "make."  It forms a
   verbal noun _fictio_ from which we get the word "fiction."
D: Daddy, do you mean that Sir Isaac Newton thought that all
   hypotheses were just _made up_ like stories?
F: Yes--precisely that.
D: Oh. . . . Daddy, who invented instinct?

F: I don't know.  Probably biblical.
D: But if the idea of gravity links together two descriptive
   statements, it must be an hypothesis.
F: That's right.
D: Then Newton did _fingo_ an hypothesis after all.
F: Yes--indeed he did.  He was a very great scientist.
D: Oh.

D: Daddy, is an explanatory principle the same thing as an
   hypothesis?
F: Nearly, but not quite.  You see, an hypothesis tries to
   explain some particular something but an explanatory principle
   --like "gravity" or "instinct"--really explains nothing.
   It's a sort of conventional agreement between scientists to
   stop trying to explain things at a certain point.
D: Then is that what Newton meant? If "gravity" explains nothing
   but is only a sort of full stop at the end of a line of
   explanation, then inventing gravity was not the same as
   inventing an hypothesis, and he could say he did not _fingo_
   any hypotheses.
F: That's right.  There's no explanation of an explanatory
   principle.  It's like a black box.
D: Oh.

D: Daddy, what's a black box?
F: [. . .]

        --Quoted from G. Bateson, "Metalogue: what is an
        instinct," in _Approaches to Animal Communication_, 1969,
        reprinted in _Steps to an Ecology of Mind_ pp. 38 ff.

I recommend the remainder, let's just have a conventional agreement
that I won't type any more here.

        Bruce
        bn@bbn.com
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU