Ogas and Gaddam take a very broad view of the mind as “a physical system that converts sensations into action”. At face value, this grants a mind to thermostats and robots as much as to living entities. “A mind responds. A mind transforms. A mind acts,” they write. But the same is true of many machines. What, then, distinguishes a mind? If it’s sentience or awareness, the authors give a confusing picture. They say the “self-awareness” of an amoeba is “piddling” — and later seem to deny this quality to all organisms except vertebrates.