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Theoretical Terms/th.t. / Fraassen: they have a meaning only by their association with observables. - Therefore, two theories can say the same thing, although they formally contradict themselves! - But they only contradictory if regarded as literally. - Positivism: thesis: the importance of the th.t. comes from the observable - Positivism: they agree in their observational consequences.
th.t. / Fraassen: it is often not clear whether they refer to concrete or mathematical entities. - E.g. "powers"/power: sometimes regarded as not specifically mathematically, only the existence of certain features is maintained. - This is controversial.
B. van Fraassen
The Scientific Image Oxford 1980