The debate on the a fortiori and the universal that took place between April 1914 and April 1919 in the journal Mind has a double interest for argumentation theorists. First, the discussion is an example of a philosophical polylogue that exhibits the characteristics of a quasi-engaged dialogue (Blair Blair, J. A. (2012 [1998]). “The Limits of the Dialogue Model of Argument”. Argumentation 12, pp. 325–339. Reprinted in J.A. Blair, Groundwork in the Theory of Argumentation, pp. 231–244. Dordrecht: Springer, 2012.), confirming (...) Blair’s hypothesis that journal papers and scholarly monographs can be analyzed as turns in non-engaged or quasi-engaged dialogues. It could be said that philosophical argumentation is dialectical but not dialogical. Second, the debate is a discussion in argumentation theory. Generalism in the theory of argument claims that the very possibility of arguing depends on a suitable supply of general rules that specify what kinds of conclusions can be drawn from what kinds of data, while particularism denies this. Although the terminology may be alien, I will also show that the debate on the a fortiori and the universal was a debate on generalism and particularism. (shrink)