We can define a hallucination, roughly, as a perception that exists in the absence of external stimulus and feels real. The question I’d like answered is, how do we determine that there is, in fact, a lack of external stimulus?
We cannot reasonably assert that our ordinary waking consciousness is necessarily the broadest, most accurate lens through which one perceives the external world.
The human nervous system has evolved over the last few hundred million years to deal with a very specific and specialized set of circumstances, namely survival on the plains of Africa.
Our brains seem to be best adapted to solving the problems of spotting predator and prey, picking berries and seeds, and finding shelter. Our consciousness, for the longest time, according to modern science, has been concerned with this very limited cross-section of what we’d now term as reality.
Now this mode of operation is not necessarily conducive to activities such as abstract reasoning, logic, conceptual thinking and so on. So I think what we have here is a case of familiarity being confused with an optimal state.
I’m not hinting at anything supernatural here, but perhaps something transcendent, in the following sense.
There are many experiences common to psychedelic states such as geometric patterning, increased visual acuity, perception of cognitive processes as clear, ordered and calm, heightened ability to reason in the abstract and make free associations and so on. One possible explanation for these phenomena is that one can access information, which is stimulus from the external world that is inaccessible from a state of sobriety. This is because said information confers little to no survival value to an organism that has spent the majority of its evolutionary lifespan foraging in grasslands.
If our nervous system is stimulated in a certain fashion resulting in a heightened sensitivity to stimulus, we can infer that there is a possibility that information below the ordinary perceptual threshold may become perceptible under these conditions.
I think to term the psychedelic experience a hallucination is to put the unknown into a box and call it known. It demonstrates a lack of intellectual rigor on behalf of those willing to put their names to such pseudo-scientific reasoning.
I believe that this is an area of science which has been exposed to the same sort of ignorance and dogmatism as Darwin’s theories when they were put before the religious beliefs masquerading as science of the time. The potential uses of these chemical catalysts could have a similar level of significance if we allowed science to look at them without the blinkers of Puritan ideology.
Here are a few related studies and articles: