Ha. lol! So now we're back to Descartes and, "Cogito, ergo sum" ; -)

In the article, it describes Seth's ideas further, suggesting that the brain uses a mix of sensory data and prediction to generate our perceptions. It's that predictive input that he refers to as the hallucination. It also notes that if the prediction is sufficiently different from reality, then it engages in some sort of course correction. So the word "hallucination" is just shorthand for describing a more complicated idea.