因明入正理論疏 3.185

3.185

述曰：此出比體，謂若有智，藉三相因，因相有三，故名為眾，而方觀境義也。

The Commentary says: This shows the essence of inference. It means that if there is a cognition, it relies on a reason of three characteristics—the characteristics of the reason being three, hence called "multiple"—and only then does it observe the meaning of the object.