Summary: Does your temperament determine your fate? Since Plato's time, thinkers and storytellers have believed that each of us comes into the world with a discernable disposition and innate talents. By the beginning of the twentieth century, though, the notion of distinct personality types had fallen out of favor. Psychologists bought into Freud's basic assertion that unconscious drives determined behavior, and behavioral scientists accepted Pavlov's theory that all humans are a bundle of specific responses to specific stimuli. It took the publication of Carl Jung's Psychological Types in the 1920s to revive the debate about temperamental differences.

An important dividing line for Jung was whether people recharged their batteries by going out into the world (extrovert) or retreating from it (introvert). He also categorized individual psychological makeup based on the strength of a person's thinking, feeling, sensing and intuiting responses. Jung's work stayed largely theoretical until Isabel Meyers and her mother, Kathryn Briggs, created a test that measured where people fit within Jung's model. First used in schools during the 1950s, The Meyers-Briggs Type Indicator (MBTI) has been taken by millions of people who want to figure out where their aptitudes lie, and is still widely used today.

David Keirsey's contribution to temperament theory has been to both deepen Meyer's work by tracking its historical antecedents (there seems to have been consensus through the ages that there are four basic temperaments) and to broaden it by describing how the personalities measured by the MBTI actually behave. Please Understand Me, first published in 1978, sold over two million copies. In Please Understand Me II, published in 1998, Keirsey updates his test for sorting yourself into one of four broad temperaments: Artisan, Guardian, Idealist and Rational. Each of the four types is subdivided into four finer-grained variants based upon how abstract or concrete you are, and whether you're cooperative or utilitarian in your use of tools and resources. Besides giving extensive descriptions of how the four temperament types operate in the world, he ties them to the type of intelligence they are most likely to use - tactical, logistical, diplomatic, or strategic. He also makes some generalizations about how each temperament performs in mating, parenting and leading.

According to Keirsey, there is no right or wrong temperament. What people do wrong is to try and "remake our companions in our own image" - which he labels the Pygmalion process. He makes the sensible point that our passage through this world will be much smoother if we understand our own strengths and limitations, and understand how others either resemble or differ from us. Keirsey, and Meyers before him, achieved popular success because what they measure and describe conforms with what people see when they operate in the real world. Chances are high that you'll recognize yourself as one of Keirsey's temperamental types, and will learn something about yourself by reading what drives that particular temperament. You'll also see that people who don't react the way you do aren't being bloody minded. They're following the promptings of their temperamental imperatives, just as you are.

All theories have limitations, and, to this reader, Keirsey's seems to underweight other elements that influence our response to the world. These elements include the language you think in, the country you were born in, the historical moments you live through, your physical makeup and your physiological functioning. To take two random examples, the Guardian temperament is supposed to have a great respect for authority. But Guardians who came of age in the 1960s may have imbibed some anti-authoritarian cultural biases that thrust them outside the temperamental norm. If you're an Idealist who is six foot seven and weighs 300 pounds, you may have spent less time developing the empathy for which Idealists are noted because people react more to you than you to them.

All the data about temperament come from personal observation; there is as yet no hard scientific grounding for Keirsey's conclusions. The ultimate theory of temperament awaits the discovery of specific gene sequences that create the various personality types. (How this will foot to those who believe in god-given abilities should make for some interesting debates.) Until scientists decrypt the molecular basis of temperament, we'll have to rely on the close observation and insightful conclusions Keirsey and his predecessors have supplied. Temperament theory is a handy tool. Used in conjunction with other types of self-knowledge, it helps you figure out who you are, which will help you to understand, and perhaps embrace, your fate.