Full Idea
Definition cannot take the same form in philosophy as it does in mathematics; the imitation of mathematical procedure is invariably in this respect not only unfruitful, but perverse and most harmful in its consequences.
Gist of Idea
The use of mathematical-style definitions in philosophy is fruitless and harmful
Source
Edmund Husserl (Ideas: intro to pure phenomenology [1913], Intro)
Book Reference
Husserl,Edmund: 'Ideas: general introduction to pure phenomenology', ed/tr. Boyce Gibson,W [Routledge 2012], p.6
A Reaction
A hundred years of analytic philosophy has entirely ignored this warning. My heart has always sunk when I read '=def...' in a philosophy article (which is usually American). The illusion of rigour.