Pharmacogenic Derealization as a Paradigmatic ASC

Although the concept of altered state of consciousness (ASC) is problematic regarding its definition, scope and limits, there is no doubt that ASCs exist. As a concrete example of this I here bring about the case of drug-induced derealization. I first describe, mainly in a phenomenological perspective, the effects that certain so-called hallucinogenic substances have on the human psyche. I specifically focus on the effect of derealization, which we can define as the feeling that the external world is unreal, distant, strange or devoid of sense. Then I approach both the phenomenology and the epistemology of perception through the analysis of the relationship between the content of sensory experience and its conceptualization. This should allow us to understand derealization in terms of a deficient or inadequate relation holding between the experience of the world and its conceptualization, as the latter renders meaningful the former.  Lastly, I will sketch a theory of Kantian and enactivist inspiration in an effort to explain how we acquire and maintain the feeling that the external world is real (this is to say, our sense of reality), and how we may lose it. More generally, in this article I endeavor to show that mental phenomena produced by the ingestion of psychedelic substances are an optimal way to study ASC in a rigorous and prolific manner, whether scientifically or philosophically.