McLuhan often noted that a rigorous investigation of media and communication could not be based on particular values.  For particular values were rooted in prior media and, because media study was essentially comparative, it could not presuppose the privilege of some one of them.

This did not mean, however, that he had no ethical position. He had converted to Catholicism as a young man and as he aged he became more and more engaged with issues surrounding war and peace, abortion and euthanasia.

The basis of his ethics was comparativism itself:

the greatly increased speed of action and reaction (…) of electronic information movement compels organizations to assume an ethical character in the sense of having inclusive rather than exclusive purposes. Specialized lines of development are intolerable, when every line crosses every line. That is to say, that the dialogue now characterizes the interplay of things themselves, and any effort to understand or control such situations by any means less inclusive than the dialogue will scarcely work. (McLuhan to Claude Bissell,  May 6, 1960, Letters 273)

The environment as a processor of information is propaganda. Propaganda ends where dialogue begins. (The Medium is the Massage, 1967)¹