Positive thinking is at once the most widely embraced and the most frequently reviled philosophy in America. As I explore in my forthcoming book, One Simple Idea: How Positive Thinking Reshaped Modern Life, the gospel of positivity grew out of mystical and occult subcultures in America starting in the mid-nineteenth century and went on to become closest thing America has to a national creed.
Most of our modern ideas of positive thinking come from an American spiritual movement called New Thought, which promulgated the principle that thoughts are causative. This belief crisscrosses cultural lines from the New Age to evangelical churches. It underscores much of our political jargon, from Ronald Reagan ("nothing is impossible") to Barack Obama ("yes we can"), as well as our best-known commercial slogans from Nike's "just do it" to the U.S. Army's "be all you can be."
Positive thinking, sometimes called the mind-power movement, forms the foundational idea behind business motivation, mind-body medicine, placebo studies, and almost all varieties of self-help. It is the most influential psycho-spiritual idea of our, and perhaps of any, time.