Starting from the classic books of Ian Hacking ("Taming of Chance", 1989) and Theodore M. Porter ("The Rise of Statistical Thinking" 1820-1900, 1986) the essay aims to reconsider the role played by the professional practices of technicians and bureaucrats in the development of statistics, and to challenge the close link between statistical law and indeterminism. The author shows the essential function played by some theoretical debates in transforming statistics from a descriptive discipline to an explanatory one. Statistical regularities opened up new epistemological perspectives only when several scientific disciplines asserted their specificity with the consequent need to investigate reality by constructing different models. Such models do not present themselves as copies of the real, yet as a possibility to be submitted to the test of experience. In this new context regularities are not those of the censuses but those sought on the basis of particular hypotheses and constructed so as to be put to test. Reflection on statistical regularities thus led to new deterministic perspectives rather than to the affirmation of indeterminism.