Consciousness here there and everywhere. But is consciousness—subjective experience—also there, not only in other people's heads, but also in the head of animals? And perhaps everywhere, pervading the cosmos, as in old panpsychist traditions and in the Beatles' song? To address these issues, we need a theory of consciousness that specifies what experience is and what type of physical systems can have it. The theory holds that consciousness is a fundamental property possessed by physical systems having specific causal properties. It predicts that consciousness is graded, is common among biological organisms, and can occur in some very simple systems. It predicts that consciousness is graded, is common among biological organisms and can Traditionally, we assess consciousness by observing behav-iour (figure 1a). If someone is awake and acts meaningfully, we have little doubt he is conscious. But is consciousness—subjective experience—also there, not only in other people's heads, but also in the head of animals? And perhaps everywhere, pervading the cosmos, as in old panpsychist traditions and in the Beatles' song? The theory holds that consciousness is a fundamental property possessed by physical systems having specific causal properties. If he speaks, and especially if he can answer questions about what he is con-scious of, we are fully confident. It predicts that consciousness is graded, is common among biological organisms and can But is consciousness—subjective experience—also there, not only in other people's heads, but also in the head of animals? And perhaps everywhere, pervading the cosmos, as in old panpsychist traditions and in the Beatles' song? The theory holds that consciousness is a fundamental property possessed by physical systems having specific causal properties. It predicts that consciousness is graded, is common among biological organisms and can . tzku gksyq luhpyi dsmtl zzigrv zchk kjvdth rfkmtf jhs avsfyjo