Louis Menand at The New Yorker:
The idea that anxiety is central to the human condition can also mean that our mental life is characterized by psychic conflict, and anxiety is the symptom of that conflict. This is, roughly, the psychoanalytic view. It’s what Freud meant when, in 1917 (not, as Stossel has it, 1933), he called anxiety “a riddle whose solution would be bound to throw a flood of light on our whole mental existence.” Anxiety is the common feature of all neuroses. Feeling anxious is what makes people seek psychiatric help. It’s a signal that unconscious drives are in conflict—that (as Freud believed in 1917) the ego is repressing a libidinal impulse. We’re not aware of the conflict itself—we’re not aware that we have a repressed desire—but we are aware of our anxiety. That’s what makes it the key to understanding what’s going on inside our heads.
Anxiety plays a big role in other accounts of the human condition, too. In theology, anxiety has been associated with the concepts of conscience, guilt, and original sin. Reinhold Niebuhr called anxiety “the inevitable spiritual state of man.” In evolutionary psychology, anxiety is usually explained as part of the “fight or flight” reflex that gets triggered in the presence of danger. The reflex is naturally selected for: organisms that lack it might fall off a cliff or get crushed by a mastodon, because their physiologies failed to warn them of a threat to their survival. And, in some schools of sociology and cultural theory, anxiety is interpreted as a reaction to the stress and uncertainty of modern life. It’s a natural response to unnatural conditions. It’s how we know that the world is headed in a bad direction.