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functional laws / Armstrong: Q = f (P): it may well be that P has no value at any time - for simplicity: better not to accept this as a "missing" value, but as a value.
functional laws / Armstrong: Problem: missing values (relationship to uninstantiated laws) - form: (x) ((P) (Px> (EQ) (Qx & Q = f (P)) - many authors: laws involve rather physical values than properties - ArmstrongVs: a function such as "rest mass in kg" will map an object to 5.3, due to a property of the object, i.e. in this case the mass that it has, and not vice versa.
AR II = Disp
D. M. Armstrong
Dispositions, Tim Crane, London New York 1996
What is a Law of Nature? Cambridge 1983