DOI: http://dx.doi.org/10.5007/2175-7984.2016v15n34p160 The notions of “insane epistemology” and “heuristics of insanity” refer to a methodological device that has proven fruitful in a variety of research domains, namely the plunge into the realm of the “pathological” as a pathway to illuminate “normal” modalities of action and experience. Resorting to this strategy on the plane of sociological characterizations of human conduct, the article harnesses phenomenological and existential descriptions of schizoid and schizophrenic experiences, not only to understand these in the light of the praxeological theory of action, but also to deepen the praxeological theory of action in the light of what such descriptions teach us about the multiplicity of ways of being-in-the-world displayed by the anthropos. The study defends that these transformations, despite their psychic costs, must not be conceived as mere functional deficits, but rather as complex existential attitudes which defy, in practice, certain postulates of the praxeological theory of action: the grounding upon tacit beliefs is replaced with a hyper-reflexive compulsion, the pragmatic relationship with material objects gives way to a quasi-philosophical perplexity in face of their mere reality, the inter-subjective agreements that offer familiarity and order to social reality in a given culture are perceived in their radical ontological arbitrariness, and the estrangement from one’s own body ceases to be a playful Cartesian skepticism so as to become a profound existential experience.