In this thesis I argue that 'critical theorists', and the left in general, have paid insufficient attention to the psychological and pathological dimensions of the problems of modernity, including its environmental predicaments. To address this theoretical lacuna, I critically examine the conceptions of 'collective pathology' and 'higher sanity' as articulated in the relatively neglected work of Theodore Roszak and Ken Wilber, my position being that these two thinkers offer the most sophisticated readings of modernity and its 'ecological crises' in terms of pathology currently available. I also demonstrate a number of crucially significant implications of their work for contemporary critical theory. Consequently, the thesis is organized in two parts: in Part One I examine the work of Roszak and Wilber; in Part Two I explore major, critical implications of their work. The thesis begins with a critical examination of the concepts of 'pathology' and 'higher sanity' in Roszak and Wilber. I subsequently show how a critique in terms of these concepts alerts us to specific legimating tropes in ecocritical theory which have deligitimized competing discursive practices, and how such conceptions address and illuminate an ecological 'blind spot' in contemporary historical theorizing: no such study has been previously attempted. I then argue that conceptions of 'pathology' and 'higher sanity' indicate that debates between eco-centric notions of nature as 'real' and postmodernist notions of nature as a 'social construction' represent a double-bind; a false problem caused by specific unconscious and/or unacknowledged presuppositions. I go on to demonstrate how this double-bind can be overcome by, for example, exploring the psychology of Derridean deconstruction. In its examination of the critical implications of 'pathology' and 'higher sanity', this thesis can be read overall as a way of regrounding a radical ecological critique that is fully 'postmodem' - in the sense of aporetic - yet 'transcendent' at the same time. Consequently, this study is offered as an original resource for radical environmental activists who consider that the 'grounding' of their critique is undermined by postmodern and/or deconstructionist anti-foundationalism; I argue that such fears are 'groundless'.