Mijuskovic writes “The Simplicity Argument versus a Materialist Theory of Consciousness” to challenge A. M. Armstrong’s A Materialist Theory of Mind. The reader will immediately notice his thought is more refined in this presentation as an overarching philosophy of mind that is juxtaposed with that of Armstrong’s. Just two years after the publication of The Achilles of Rationalist Arguments, Mijuskovic presents a philosophical defense that spans more than two millennia of Western philosophy from Plato to Sartre. This particular presentation also illustrates a future line of reasoning that Mijuskovic develops in Contingent Immaterialism. As a theory of consciousness, the simplicity argument promotes an existential freedom that can be solipsistic at times – as seen in Sartre.  Mijuskovic remarks, “[i]n Sartre’s early works, the Simplicity Argument functions to ground an explosive, outward directed model of freedom.” [1] The resultant isolation or loneliness produced explains some of the driving subconscious forces humans possess. In addition to the immaterial premise, loneliness is a major topic of research for Mijuskovic as a natural progression of thought from the theory of consciousness presented in this article.