A central concept of the constructivist philosophy of science is the term ‘protoscience’. From an orthodox point of view, protosciences are bound to give the so called ‘measurement-theoretical Apriori’ (‘mestheoretisches Apriori’) for a science. Protophysics for example (operationally) defines the quantities ‘length’, ‘time’, and ‘mass’. Thereby it yields some basic physical laws, which usually are regarded as “laws of nature”, but in fact follow already from the definitions of the basic quantities.