We know people can have only 50% of a full brain and yet be conscious, and we also know that destruction of a few tiny pieces of the brain can result in a loss of consciousness in the sense we mean it here. The commonality is that neuron systems are required; individual neurons are not enough, nor is an entire intact animal brain without certain structures.<p>The line is arbitrary, but it doesn&#x27;t matter so much. The factual reality is that neuron systems are what we can currently (currently! this may change) prove gives rise to consciousness, regardless of philosophical attempts at violence against the science.