Personal Knowledge #2

The value of a theory may be judged on its fruitfulness. Michael Polanyi wrote the following about truth and fruitfulness.

"You cannot define the indeterminate veridical powers of truth in terms of fruitfulness, unless 'fruitful' is itself qualified in terms of the definiendum. The Ptolmaic system was a fruitful source of error for one thousand years; astrology has been a fruitful source of income to astrologers for two thousand five hundred years; Marxism is a fruitful source of power for the rulers of one third of mankind. When we say that Copernicanism was fruitful, we mean that it was a fruitful source of truth, and we cannot distinguish its kind of fruitfulness from that of the Ptolmaic system, or of astrology, or Marxism, except by such a qualification. To use the word fruitful in this sense, without acknowledging it, is a deceptive substitution, a pseudo-substitution, a Laplacean slight of hand.
     But even when fruitfulness is taken to mean the capacity of leading to new truths, it is an insufficient characterization of truth. Copernicanism could have well been a source of truth ... even if it had been false. But the Copernican system did not anticipate the discoveries of Kepler and Newton accidentally: it led to them because it was true " (p. 147).

"The mark of true discovery is not its fruitfulness but the intimation of its fruitfulness" (p. 148)

I guess that he meant the following by 'intimation': the action of making something known, especially in an indirect way.