In accord with the perception of its cause, knowledge is supposed to be based on external objects. But from the standpoint of reality, it is held that the external cause is no cause. (G.K. IV.25)
There is an intimation here of the advanced position of what I have been calling 'non-numerical identity' between the object and the vritti. An object in this sense is not the cause of itself. The initial stage is of course the classical causal therory of perception.
Meaning : "The Chitta (mind) does not touch the object ; for that reason only it does not touch the Arthabhasa (the reflection or appearance of an object). For, Padartha (an object) is verily Abhuta (not really existing) ; therefore, apart from it Arthiibhasa also does not exist." (Translation or import of 4: 26 Gaudapada Karikas from The Essence of Gaudapada by Sri S.S.S.)
"Consciousness has no contact with objects; so also it has certainly no contact with appearances of objects. For according to the reason adduced, an object has no existence, and an illusory object is not separate from the awareness". (Swami Gambhirananda trans. Advaita Ashrama pub.)
Gaudapada is here ascribing an Berkeleyan turn to the Vijnanavadin and in the subsequent verse takes their position to its inevitable conclusion:
Consciousness does not ever come in contact with external objects in all the three states. There being no external objects how can there be any base false apprehension of it.
In Sankara's own critique of the Vijnanavadin position he uses that point. (cf. B.S.B. II.ii.28) In his commentary on the Mandukya Karika of Gaudapada he states:
The text starting with, "In compliance with the perceptions of its cause, Knowledge" (IV.25) and ending with the previous verse, which represents the view of the subjective idealists among the Buddhists, is approved by the teacher (Gaudapada) in so far as it refutes the view of those who believe in external objects. Now he makes use of that very argument (of the idealists) as a ground of inference for demolishing their own points of view:
Hence consciousness has no birth, and things perceived by it do not pass into birth. Those who perceive the birth of that consciousness, may as well see footmarks in space itself. (G.K. IV.28)
The upshot is that nothing gives rise to consciousness. Consciousness always is - unborn or ajati. Even if wholly wrong the vijnavadin is half right.a