G.E. Moore, a prominent common-sense philosopher, famously used arguments like the one quoted to refute idealism, particularly the notion that "to be is to be perceived" (esse est percipi). Idealism, championed by figures like Berkeley, fundamentally claims that physical objects and their qualities are mind-dependent; they exist only insofar as they are perceived.

Moore's statement, "Blue is one object of sensation and green is another, and consciousness, which both sensations have in common, is different from either," is central to his "Refutation of Idealism." He argues that when we experience a sensation, say of blue, there are two distinct elements:

1. The act of consciousness or the sensation itself (a mental event).

2. The object of consciousness or the quality (blue, which is external to the mental act).

Moore contended that idealists mistakenly confused or identified the sensation (the mental act) with the object of the sensation (the quality being perceived). If "blue" were identical to the sensation of "blue," then the sensation itself would literally be blue, which is nonsensical. Similarly, the conscious awareness we have of both blue and green is distinct from blue or green themselves.

By demonstrating this distinction between the mental act of perceiving and the non-mental object of perception, Moore aimed to show that objects (even qualities like colors) are not merely internal states of the mind. This opens up the possibility for objects and their qualities to exist independently of being perceived, thereby directly undermining the idealist's core tenet that existence is dependent on perception. Moore concluded that the existence of an external, mind-independent world is a matter of common sense and that the idealist argument rests on a fundamental confusion.