瑜伽論記 2.92

2.92

成中，所知勝解愛樂為先者，夫欲立義，須解自他宗，故言所知勝解。又隨自樂，為所成立法，此為因也。

Regarding 'establishing': 'taking the resolute conviction and inclination toward what is to be known as prior' means that whenever one wishes to establish a proposition, one must understand both one's own and others' tenets; hence it says 'resolute conviction toward what is to be known.' Moreover, according to one's own inclination, one establishes a thesis; this serves as the cause.