Science and technology have always been decisive factors in war. Archers were capable of killing more effectively than warriors armed with spears. Armies equipped with repeating rifles claimed a distinct advantage over those armed with muskets. The United States’ ability to produce the atomic bomb led to the surrender of Japan at the conclusion of World War II. It is obvious, in other words, that science, technology, engineering, and math have an important role to play in guiding the evolution of national militaries. What may be less obvious is that advances in psychology may have an even more important role to play, particularly in the types of conflicts increasingly common in the twenty-first century.

There are several reasons this is the case. The major wars of the twentieth century involved full-intensity conflict between nations, with success often measured by territory gained or lost. Countries that could exploit advances in chemistry to produce more lethal explosives or leverage the science of physics to engineer faster and more maneuverable airplanes stood a better chance of defeating the enemy. These applications of science and technology had a direct impact on definable military objectives.

Contrast this with the wars of the twenty-first century. In the United States' most recent conflicts, the primary adversary hasn't been other countries but, rather, ideologically motivated coalitions of fighters determined to achieve their political goals with unconventional tactics, including suicide attacks and remote bombings. Currently, ISIS provides a case in point. In asymmetric warfare of this sort, it is hard to determine and locate the perpetrators of an attack.