His entire method is what we would call psychological today. In reading Sun Tzu, you will not learn anything about the weapons or types of troops used in China 2,500 years ago. Sun Tzu focused his work on the only weapon that never gets outdated: the human mind.
The positions that matter in Sun Tzu’s systems are those positions we create in the human mind. In any social competition, our success depends upon other people. People decide who to support, oppose, or ignore based upon how they see the positions of others in their mind.
Over the years, I have run across several articles on psychology echoing the underlying principles of decision-making outlined in Sun Tzu’s system (several articles about the science here). However, during most of my work with Sun Tzu’s ideas, I hadn’t spent a lot of time keeping up with modern psychology until recently when I discovered the psychology professor Jordan B. Peterson’s YouTube videos. Many of Peterson’s insights about dominance hierarchies are modern restatements of Sun Tzu’s principles.
One of the most interesting parallels is better Sun Tzu’s five characteristics of a commander and the five aspects of personality taught by Peterson. Especially interesting for me as a translator are the differences in the language they use to describe the same thing. For example, what a military commander sees as courage, the psychologist sees as its opposite, neurosis.