Willard Van Orman Quine

Indeterminacy of Translation 169
This thesis is independently interesting. The broad idea is that
our theory of the world is underdetermined not just by the evidence
we may happen to have encountered but by all possible evidence.
(A thorough discussion of the thesis – out of place in this chapter –
would need to consider just what is to be counted as evidence and
also whether the thesis requires the possibility of competing theories
that are not just different but mutually incompatible.)
The first point to notice is that the indeterminacy of translation
is not to be regarded as just a special case of the underdetermination
of theory. Some critics have been unimpressed by that distinction,
but it seems reasonably clear. Granted that physics itself is
underdetermined, the indeterminacy of translation is “additional”
in the following sense. Suppose we regard current physics as fixed
and take “the whole truth about nature” to be representable by a set
of statements describing every detail of the universe, past, present,
and future, in terms of that fixed physics. The claim is that this assumed
determinate physical reality fails to fix translation. It still
leaves room for the construction of mutually incompatible translation
manuals that nevertheless fit the totality of those supposedly
fixed physical facts. 12
Pressing from above consists of an argument that attempts to exploit
the underdetermination of physics itself. The argument does
not purport to be completely general, it seeks only to establish the
indeterminacy of the translation of as much of physics as is itself underdetermined.
Consider the radical translation of a radically foreign
physicist’s theory. The translation starts by matching up observation
sentences of the two languages “by an inductive equating of stimulus
meanings.” As usual, analytical hypotheses are required, and
Quine claims that their “ultimate justification is substantially just
that the implied observation sentences match up.” But, he goes on,
the same old empirical slack, the old indeterminacy between physical theories
[the underdetermination of theories], recurs in second intention. Insofar
as the truth of a physical theory is underdetermined by observables, the
translation of the foreigner’s physical theory is underdetermined by translation
of his observation sentences. If our physical theory can vary though all
possible observations be fixed, then our translation of his physical theory
can vary though our translations of all possible observation reports on his
part be fixed. (RIT 179–80)
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