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From: janw@inmet.UUCP
Newsgroups: sci.philosophy.tech
Subject: Re: Knowledge and the Academics
Message-ID: <160200019@inmet>
Date: Fri, 19-Jun-87 23:26:00 EDT
Article-I.D.: inmet.160200019
Posted: Fri Jun 19 23:26:00 1987
Date-Received: Fri, 26-Jun-87 06:39:39 EDT
References: <16224@brahms.Berkeley.EDU>
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Nf-From: inmet.UUCP!janw    Jun 19 23:26:00 1987


[werner@aecom.UUCP ]
>	I'd like to point out the difference between heritable and
>genetic (or inheritable).

>	The number of digits a person has is determined by genetic
>factors, but that number has a very low heritability.
>	Skin color in the United States is very heritable.  In Sweden
>and Japan, it has a very low heritability.

>[...]
>	So, I ask you, before comitting yourself to the argument,
>think several times about this definition of heritability.  It is
>definitely a non-trivial point.

The distinction *is* non-trivial,  and  Craig's  caveat  is useful.

A counter-caveat: when Craig speaks of what  "heritable"  "is",  he
means  a technical  definition of the term in a special field. In
general usage, heritable means  the  same  thing  as  inheritable
(e.g.,  Webster's  New  Collegiate: "heritable 1: capable of being
inherited or of passing by inheritance 2: hereditary").

The technical usage has merit because it makes an important  dis-
tinction;  still, it cannot claim to be the only one - any more than
the mathematical definition of "group" or the physical definition
of "charm" can.

Whichever  definition  we   choose,   the   answer   to   whether
"heritability", or "inheritability" of intelligence is a scien-
tific issue, remains the same. It is not a scientific  issue,  as
long as there's no scientific definition of intelligence.

Moreover, it is obvious from the technical definition  that  any
trait can be "heritable" in an appropriately selected population,
and not "heritable" in another one. 

Therefore, as Mary K. Kuhner writes in sci.misc, "it is very easy
to draw nasty false conclusions from heritability statistics".

One of them is the popular assertion that  "intelligence  is  80%
nature, 20% nurture", which is triply misleading:

# it is based on long-discredited data;

# it is totally dependent on how much "nurture"  varies
in the population described (it is as if physicists believed that
"according to statistical studies, 80% of conductor  resistance
depends on the material, and only 20% on the cross-section");

# and it substitutes for "intelligence" some indicator whose con-
nection with the vague but important concept of "intelligence" is
arbitrary and counter-intuitive. The first flaw can  be  corrected
by producing honest data, the other two are more profound.

The history of this myth ought to be relevant to the question  of
academic  credibility.  

		Jan Wasilewsky