The Critical Rationalist Vol. 01 No. 04 ISSN: 1393-3809 31-Dec-1996
5.1.5 Misconception 3: Adaptation
5.1.3 Misconception 1: Logic
(66) Spencer's phrase does reduce strictly to a tautology if "fitness" is equated with "survival"; that is, the phrase is read as a definition of fitness (and definitions are, of course, a paradigmatic case of tautology). This formulation of the tautology argument is the most common; a good example would be that of Popper (1965, pp. 241-242).[9] As Dawkins puts it, this kind of argument is "a remarkable example of the elevation of words above their station" (Dawkins 1982, p. 181).
(67) This misconception leads to tautology regardless of whether we take "survival" to mean I-survival or L-survival. Both cases are conceptually possible, although they have quite different flavours. In general, writers suffering from this misconception are not clear about which sense they intend. In fact, the most likely scenario may be a failure to distinguish that there are two possible, but distinct, strictly tautologous interpretations--for if that fact is once recognised, the possibility of a non-tautologous (and correct) interpretation more or less immediately presents itself.[10]
(68) The first distinct case of this misconception is this:
Case 1: the I-survival of the I-survivors
This amounts to defining fitness as (mean) I-survival.
(69) Now this interpretation is not "incorrect". As already discussed above, I-survival is indeed a possible, though extremely crude, measure of S-value; and "fitness" can be (and commonly is) interpreted as synonymous with S-value. So it is not entirely unreasonable to define fitness as (mean) I-survival (other things, particularly fecundity, being equal).
(70)
But of course, under this interpretation, the phrase is no longer
an expression of (the theory of) natural selection--it
is merely a preliminary definition. Pointing out its
tautologous nature cannot impinge at all on the status of
.
(71) The remaining variant on this misconception is:
Case 2: the L-survival of the L-survivors
This amounts to defining fitness as L-survival.
(72) Unlike case 1, this is hardly even a coherent definition. Since L-survival is (at any given time) a binary valued quantity, it is at least peculiar to equate it with "fitness" which, on any common sense interpretation, should be continuous valued.
(73) But let us stretch this point, for the time being. We could consider the phrase as equating fitness with L-survival, regardless of whether natural selection is known to be operational. But, as far as I am aware, this would be a usage of "fitness" which has never been seriously proposed, is counterintuitive, and would be of no apparent utility.
(74) This leaves only the possibility that we consider the phrase as a definition of fitness only in cases where we have prior, independent, knowledge of the operation of natural selection.
(75) Well, in this case we cannot say it is
positively incorrect--the operation of selection
guarantees precisely that L-survival will be
related to S-value (the "normal" meaning of
fitness), as already discussed for the correct,
non-tautologous, interpretation of Spencer's phrase.
At this point we are back to a similar situation to
that obtaining with Case 1: the interpretation can
"reasonably" be adopted, but it is no longer
an expression of (the theory of) natural selection--it
is merely a preliminary definition (and a rather
confusing one at that). Adopting this definition, we
would then have to introduce some additional term other
than fitness (S-value perhaps?), whose definition would
not be already contingent on the outcome of
selection, before we could even formulate
properly. But, in any case, we again conclude that
pointing out the tautologous nature of this
interpretation cannot impinge at all on the status of
.
5.1.5 Misconception 3: Adaptation
5.1.3 Misconception 1: Logic
The Critical Rationalist Vol. 01 No. 04 ISSN: 1393-3809 31-Dec-1996
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TCR Issue Timestamp: Tue Dec 31 17:37:08 GMT 1996