Sentence:  ... this Notion is the Source from whence do spring, all those Amusing Geometrical Paradoxes, which have such a direct <WSD>Repugnancy</WSD> to the plain, common Sense of Mankind, and are admitted with so much Reluctance, into a Mind not yet debauched by Learning ... 
Meaning of the word marked with <WSD> tags:  The quality of being repugnant: (logical) opposition, contradiction, incompatibility.