 That being said, there are parallels that can be drawn between the positions of Stumpf and of Frege on the foundations of mathematics and on psychologism. (see W. Ewen, 2008, p. 97 f.) Several attempts have been recently made to explain these parallels, and these accounts all focus on their mutual relationship with Lotze during their stay in Göttingen in the early 1870s, while Stumpf, after his habilitation, was Privatdozent (1870–1873), and Frege pursued his studies in mathematics (1871–1873). Although it can be assumed that the two philosophers met during this period, we have no written evidence that confirms this. (W. Ewen, 2008, p. 97 f.) Historical testimony does not say whether Frege attended Stumpf’s lectures in Göttingen on Aristotle’s metaphysics, which he taught for three consecutive years, or his lectures on “inductive logic with a particular focus on the problem of natural science” that he taught during the summer semester of 1873. Nevertheless, the correspondence that Frege and Stumpf exchanged in the early 1880s seems to testify that the two philosophers knew each other. In any case, an explanation of the elective affinities between Stumpf and Frege might be found in the work of Lotze. (Stumpf, 1918, p. 7; D. Fisette, 2015a)