Pioneers of evolutionary psychology John Tooby, Leda Cosmides, and H. Clark Barrett argue in a 2003 article of the same name that “the second law of thermodynamics is the first law of psychology.”
The Law of Entropy
The second law of thermodynamics, also known as the entropy law, states that in a closed system energy must always be dissipated from high-energy to low-energy concentrations. Your cup of coffee always gives off its heat to the surrounding air and cools down over time; it will never heat up spontaneously without external energy input. By opening the system to external energy input, the coffee cup itself can gain energy when placed in the microwave, but the energy doesn’t come out of nowhere. Most of our energy comes from the sun, and the amount used to create habitable order pales in comparison to the amount constantly dumped into the empty void of space.
A related form of the entropy law relates to the statistical necessity of disorder: there are finite ways to build a sandcastle, but there are infinite ways to disperse that sand. Of all the possible interactions or possible states of matter given, most are disordered chaos. Improbable nests of order can exist that incur high energy costs to maintain, but if you zoom out far enough the entropy will always increase.
What does all this have to do with psychology?
The first law of psychology
Outlining the “First Law of Psychology,” the paper constructively criticizes psychology as a field whose prejudices about physics and biology are often misinformed — and frankly, it reads more like a biology paper. I recognize the irony that this is probably the case because the paper’s target audience is me: a psychologist who hasn’t taken a physics or biology course in years.
That makes me either the best or the worst person, depending on your attitude, to tell you why if you care about psychology you should care about entropy.
Most of us take for granted the fact that our world is in order. Beyond the universal laws of mathematics and science, order in the universe is rare. For every ordered star or galaxy formation, there are billions more light-years of disordered, mostly empty space. Rarer still is a self-sustaining, ordered system that expends energy to maintain its form (i.e., life).
Entro, Evo, Info
Most of us understand the principles of natural selection: the fittest survive, the genes of those that breed are passed on, and over time successful traits are selected. Even this explanation assumes the resulting improbable order. Most variations within and between species will be disordered errors, in accordance with the law of entropy. Only a select few traits and behavioral adaptations will stand the test of time.
This means that entropy directly evokes the process of evolution, and that evolution outputs something akin to information: the set of traits that are capable of surviving and propagating themselves. This is exactly what psychologist Steven Pinker argues in his book enlightenment now, in a chapter entitled “Entro, Evo, Info” (entropy, evolution and information). These three processes are inextricably linked and central to understanding human behavior.
Any stable psychological phenomenon, even those that appear to be entirely socially constructed, owes its existence to a precise configuration that repels entropy and expends energy to maintain its form in an open system relationship with the outside world. All of the laws we observe in psychology are stable nests of order, chosen precisely because they are anti-entropic (not in the final analysis, but in the sense that we can expend external energy to maintain biopsychosocial stability). Therefore, the second law of thermodynamics is the first law of psychology.