Spirit, soul, unconsciousness

We have many words for the inside and no proof of what it is. Spirit, soul, mind, consciousness. And, at the far end, unconsciousness: the word with which we name its absence. They are names for different planes, and it is worth not confusing them.

Traditions named the inside long before they could measure it. Almost everywhere, with the word for breath: anima and spiritus in Latin are breath, psyché in Greek is soul and breath at once, rūaḥ in Hebrew is wind and spirit, prāṇa in Sanskrit is the breath of life. To call the inside by the name of breath was not naivety: it was the best available measure, the closest sign of the life that comes and goes.

Science, today, measures correlates. Not the soul, but the physical traces of conscious states. A magnetic pulse on the cortex and the response that spreads: if the echo is rich and complex, the index rises; if it is poor and local, it falls. It is the perturbational complexity index, which tells waking from deep sleep and anaesthesia with a number (Casali and colleagues, 2013). Theories dispute the why: integrated information (Tononi, 2004), the global workspace that "lights up" a content (Dehaene and Changeux, 2011). They are powerful maps of the inside seen from outside.

But one question no measure touches. Why does all this activity come with a first-person experience, a "what it is like" to be awake? David Chalmers called it the hard problem of consciousness (Chalmers, 1995). We can say when the light is on, not why there is someone inside to see it. Science measures the correlate; experience itself stays, for now, beyond the instrument.

And unconsciousness? It is the most misread word. It is not a void, it is a state: the correlate lowers, the echo grows poor, the inside goes dark in patches. In deep sleep this largely happens, with order and permission. Elsewhere it does not.

Because the road is where loss of consciousness stops being a word and becomes a fact. A microsleep is exactly this: the inside switching off for a few seconds while the body keeps driving. Not a soul flying away, but a correlate collapsing at the wrong moment. The loss of consciousness we fear is the one that takes the wheel without us. Sleepiness can be felt: it is how close sleep is that slips away.