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Epistemic Possibility/Peacocke: the naturally species term 'tomato' has not the same pattern of epistemic possibility as the observation term 'tomato-like'. It is epistemically possible that something that is tomato-like, is not a tomato. - Square: if presented at different angles, it is epistemically impossible that it is not a square. - E.g. Pair of particles: here it is epistemically still possible that it is not the result of a collision because the terms are differently linkable in the theory. - observation terms do not need a complex of epistemic possibilities.
Weak Epistemic Possibility: that the man in front of someone is not the manager - but not that he is not the man who stands before someone.
Chr. R. Peacocke
Sense and Content Oxford 1983