 Thus, they launched verificationism.In its milder variant, Rudolf Carnap tried, but always failed, to formalize an inductive logic whereby a universal law's truth via observational evidence could be quantified by "degree of confirmation".Asserting a type of hypotheticodeductivism termed "falsificationism", Karl Popper from the 1930s onward especially attacked inductivism and its positivist variants as untenable.