How did Frege fall into the contradiction?

Citation

Sullivan P (2007) How did Frege fall into the contradiction?. Ratio, 20 (1), pp. 91-107. https://doi.org/10.1111/j.1467-9329.2007.00349.x

Abstract
Quine made it conventional to portray the contradiction that destroyed Frege's logicism as some kind of act of God, a thunderbolt that descended from a clear blue sky. This portrayal suited the moral Quine was antecedently inclined to draw, that intuition is bankrupt, and that reliance on it must therefore be replaced by a pragmatic methodology. But the portrayal is grossly misleading, and Quine's moral simply false. In the person of others - Cantor, Dedekind, and Zermelo - intuition was working pretty well. It was in Frege that it suffered a local and temporary blindness. The question to ask, then, is not how Frege was overtaken by the contradiction, but how it is that he didn't see it coming. The paper offers one kind of answer to that question. Starting from the very close similarity between Frege's proof of infinity and the reasoning that leads to the contradiction, it asks: given his understanding of the first, why did Frege did not notice the second? The reason is traced, first, to a faulty generalization Frege made Front the case of directions and parallel lines; and, through that, to Frege's having retained, and attempted incoherently to combine with his own, aspects of a pre-Fregean understanding of the generality of logical principles.

Keywords
DIRECTION; Methodology; other; principle; PRINCIPLES; Reasoning; similarity; understanding; WORKING

Journal
Ratio: Volume 20, Issue 1