When you introduce a falsehood in physical science you cannot remove
the respective truth from your theory. Rather, explicit falsehood and
implicit truth form a powerful couple able to produce virtually any
result you need. The following quotation is based on formal logic and
is an exaggeration with respect to physical theories; nevertheless it
is quite instructive:

W. H. Newton-Smith, The Rationality of Science, Routledge, London,
1981, p. 229: "A theory ought to be internally consistent. The grounds
for including this factor are a priori. For given a realist construal
of theories, our concern is with verisimilitude, and if a theory is
inconsistent it will contain every sentence of the language, as the
following simple argument shows. Let 'q' be an arbitrary sentence
of the language and suppose that the theory is inconsistent. This means
that we can derive the sentence 'p and not-p'. From this 'p'
follows. And from 'p' it follows that 'p or q' (if 'p' is
true then 'p or q' will be true no matter whether 'q' is true
or not). Equally, it follows from 'p and not-p' that 'not-p'.
But 'not-p' together with 'p or q' entails 'q'. Thus once
we admit an inconsistency into our theory we have to admit everything.
And no theory of verisimilitude would be acceptable that did not give
the lowest degree of verisimilitude to a theory which contained each
sentence of the theory's language and its negation."

As soon as you introduce the magic contradictory couple rationality
starts disappearing and you do not need valid arguments anymore.
Invalid arguments increase the power of your theory additionally:
whether "Reversible heat engines working between the same two
temperatures have the same efficiency" does or does not really follow
from "Heat never flows spontaneously from cold to hot" is a question
brothers scientists would never ask.

The falsehood enables you to demonstrate miracles and become a
divinity; the respective truth enables you to predict verifiable
results. Einstein's false principle of constancy of the speed of light
produces miracles such as time dilation, length contraction,
Minkowski's space-time, time travel etc. Einstein's (rather, Newton's)
true principle of variability of the speed of light gives correct
predictions such as the gravitational redshift factor.

Pentcho Valev