Knowledge is well described (not necessarily explained, but described) in information theory. Intelligence, sentience, consciousness, even whether something is

Knowledge is well described (not necessarily explained, but described) in information theory. Intelligence, sentience, consciousness, even whether something is alive, are fuzzy concepts. Biology has a working definitions of "living organism" that includes a way to calculate likelihood that something is a living organism, but it still is probabilistic. Understanding is another concept that depends on philosophy of the mind as opposed to concrete physical processes.