The sciences are typically divided into the physical and the psychological—or, what comes to the same thing, the natural and the social. This is not the right way to divide the class of sciences. The right division is between the sciences that study entropic systems and the sciences that study counter-entropic systems. Biology and psychology study counter-entropic systems. Physics studies entropic systems. The concept of a function—not in the mathematical, but in the purpose-related sense---is completely alien to the logic of the entropic sciences, but it is central to the logic of the counter-entropic sciences.