A dogmatist asserts a position as unquestionably true. Evidence against it is dismissed. Alternative views are not seriously considered. The word comes from the Greek dogma, meaning opinion or decree. In ancient philosophy, dogmatists were those who claimed to have found the truth, in contrast to skeptics who suspended judgment. Sextus Empiricus used the term to describe philosophers who held positive doctrines. The modern sense is pejorative: dogmatism is closed-minded certainty.

Dogmatism is not the same as conviction. You can hold a belief firmly and still revise it in the face of new evidence. Dogmatism refuses revision. It treats disagreement as error or bad faith. It can appear in religion, politics, science, and everyday life. A scientist who ignores anomalous data is being dogmatic. A politician who refuses to consider opposing views is being dogmatic. The remedy is not doubt for its own sake but a willingness to test one's beliefs and to take counterevidence seriously.

Marks of dogmatism

• Certainty. The position is held as beyond question.
• Closedness. Contrary evidence is ignored or dismissed.
• Repetition. Claims are asserted rather than argued.
• Hostility. Critics are treated as enemies.

Dogmatism is a risk for any system of belief. It is also a temptation for anyone who wants certainty more than truth.