Mystical experiences and anything to do with spirituality seem to clash with our science-obsessed age. At the HowTheLightGetsIn festival this September, psychologist John Vervaeke, philosopher Sophie-Grace Chappell, and sceptic Michael Shermer debated the role of spiritual experience in our lives, whether it really points to something beyond the everyday material world, or if it's mere hallucination. If we are to be true empiricists, as science demands of us, we need to take mystical experiences seriously, argues Ricky Williamson.

We are not transparent to ourselves. And the world is not transparent to us. Beyond our consciousness lies the unconscious – we only perceive parts of ourselves, not our whole self; much lies hidden. You are not conscious of the digestion processes taking place in your gut, or your blood circulating around your arteries, and when you raise your hand, you don’t consciously contract your muscles, the body does these things without the conscious ‘you’ playing much of a role. Imagine trying to think your way through raising your hand – I’ll contract my bicep this much, I’ll create this much increased blood flow here; these are thoughts no one has, as thankfully, the unconscious takes care of them for us.