The ontology of Sir William Petty's political arithmetic.

The method of political arithmetic elaborated by William Petty in the 17^th century is usually taken to be an instrument of better governance aimed at practical utility, and lacking any theoretical support in a natural philosophical sense. This paper argues otherwise by showing how Petty's scarce discussions of First Principles and mechanical philosophy could be viewed as constituting a theoretical background against which his insistence on using arithmetic to account for social phenomena could be interpreted more charitably. Reconstructing Petty's philosophy also helps answering why the accuracy of his numbers was not of primary importance for his scientific projects. [ABSTRACT FROM AUTHOR]