In the orbit of art, abstraction lies cozy within the compass of a modernist program described by Clement Greenberg as an outgrowth of a Kantian immanent critique:
The essence of modernism lies, as I see it, in the use of the characteristic methods of a discipline to criticize the discipline itselfnot in order to subvert it, but to entrench it more firmly in the area of its competence.
What had to be exhibited was not only that which was unique and irreducible in art in general, but also that which was unique and irreducible in each particular art.
The task of self-criticism became to eliminate from the specific effects of each art any and every effect that might conceivably be borrowed from or by the medium of any other art. 
For painting this meant the pursuit of a pure self-definition in terms of those characteristics of the medium that were formerly hidden in representational painting and thought of only negatively as limitations: the flat surface, the shape of the support, the properties of the pigment. In this way, abstraction comes to be defined in contradistinction to representation, a practice that alienates the pictorial space from its literal two-dimensionality, its defining character, by calling up the associated space of the referent.
Yet, Greenberg insists that abstraction is not the negation of representation, rather, painting comes to have an immediacy, or what he terms an at-onceness:
Painting and sculpture can become more completely nothing but what they do; like functional architecture and the machine, they look what they do. The picture or statue exhausts itself in the visual sensation it produces. There is nothing to identify, connect or think about, but everything to feel.
 Greenberg, Clement, Modernist Painting, The Collected Essays and Criticism, Volume 4 (Chicago and London: The University of Chicago Press, 1993) 85-6.
 Ibid, 88.
 Greenberg, Clement, Towards a Newer Laocoon, The Collected Essays and Criticism, Volume 1 (Chicago and London: The University of Chicago Press, 1993) 34.