Tibetan texts that belong to the genre of tenets (doctrinal classification) usually claim that the Cittamatra school refutes external existence. These texts further claim that Cittamatrin posit that 'the apprehended object and the apprehending consciousness are empty of being different substances'. They say that, according to Cittamatrin, the apprehending consciousness and the object it apprehends both arise simultaneously from a seed that was left in the mind-basis-of-all (alaya-vijñana), and that, given so, the object is not a cause of the consciousness apprehending it (as opposed to what Vaïbashikas and Sautrantika posit). Jetsün Chökyi Gyaltsen writes:
An illustration of the selflessness of phenomena is, for example, the emptiness that is a form and the valid cognizer apprehending that form being empty of being different substances.
It is difficult for me to conceive, and to admit, that Cittamatrin refute external existence altogether. It would mean they refute that one is born from a mother and a father, and so forth. Moreover, I doubt Tibetan scholars who claim that 'Cittamatrin refute external existence' because they have an agenda. Tibetan scholars often simplify (if not even caricature) their opponent's positions (in this case, Cittamatrin). So, not sticking to Tibetan literature only, my idea was to seek whether Cittamatrin actually refute external existence by reading works written by proponents of the Cittamatra school. Let us consider Suzuki, in Studies in the Lankavatara (p. 114). He writes:
As indeed the idealistic Mahayana does not admit the existence of an external world, whatever qualities we ordinarily think as belonging to the latter are creations or constructions of our own mind.
Suzuki seems to say "Cittamatra refute external existence", but he does not do so explicitly. He says "they do not admit the existence of an external world" but this does not necessarily amount to "refuting the existence of external world". As far as I know, he could be saying "We can not know anything but the aspects our consciousness takes. We can not see beyond our perceptions. We can not know for sure whether our perceptions are perceptions of something external. So, let us not bother with thinking of an external world - be it to refute its existence or claim its existence - and let us stick with what we know: that the eye-consciousness seeing blue takes the aspect of blue, and that we know nothing else."
Thus, the question is: Do Cittamatra / Yogacara explicitly refute the existence of an external world? Or do they simply "not admit, not take into acount" the existence of an external world?
References are welcome.