"Finalism, in Kant's definition, is the causality of a concept in relation to its object; it is the process whose a priori is an idea. Now the impossibility of eliminating this process from scientific enquiry is the impossibility for science to do away with ideal anticipation and hypothesis. Theory must be a priori, for without ideas there can be no observation; we see only what our preconceived ideas prepare us or predispose us to see. As Myrdal has observed: 'Theory . . . must always be a priori to the empirical observations of the facts,' since, 'facts come to mean something only as ascertained and organized in the frame of a theory.' 'We need to pose questions before responses can be obtained. And the questions are expressions of our own interest in the world; they are ultimately evaluations.' This is equivalent to Kant's observation that 'when Galileo experimented with balls of a definite weight on the inclined plane, when Torricelli . . . [etc.] and Stahl . . . [etc.], they learned that reason only perceives that which it produces after its own design; that it must not be content to follow, as it were, in the leading-strings of nature but must proceed in advance . . . and compel nature to reply to its questions'. This implies that what at first appears to be simple observation, a statement of fact, is in effect deduction, the objectification of our ideas, i.e. a projection into the world of our evaluations and pre-conceptions.
"On the other hand - and here finalism in turn is reconverted into causality, deduction into induction - the inevitable preconceptions of science are distinguished from the prejudgements of metaphysics (the hypotheses of the former from the hypostases of the latter) in that 'if theory is a priori it is on the other hand a first principle of science that the facts are sovereign'. This means that 'when observations of facts do not agree with a theory, i.e. when they do not make sense in the frame of the theory utilized in carrying out the research, the theory has to be discarded and replaced by a better one, which promises a better fit'. In other words, to be truthful, theory must acquire its source and origin in and from reality, it must be accompanied by 'basic empirical research' which must be 'prior to the construction of the abstract theory' and is 'needed for assuring it realism and relevance'.
"To summarize: value judgements are inevitably present in scientific research itself, but as judgments whose ultimate significance depends on the degree to which they stand up to historical-practical verification or experiment, and hence on their capacity to be converted ultimately into factual judgements. This is precisely the link between science and politics, between knowledge and transformation of the world, that Marx accomplished in the historical-moral field." - Lucio Colletti, "Bernstein and the Marxism of the Second International"