The Power of Positive Thinking believe and live successfully.” Peale's work came under criticism from various mental health experts, theologians, and academics. One general criticism against Peale's book was the lack of verified sources. "The Power of Positive Thinking" includes many personal anecdotes that the reader has no way of validating. The book includes stories about “a business executive”, “a man, an alcoholic”, “a famous trapeze artist”, “a friend of [Peale’s], a midwestern businessman”, and other unnamed individuals which cannot be verified from the information Peale presents with each anecdote. R. C. Murphy, a prominent psychiatrist based out of Tacoma, Washington, addresses another criticism of
Positive adult development and Langer (1990). Four postformal adult stages of development beyond the formal stage have been discovered in a wide variety of domains. The total number of stages across the life span now stands at 15. Periods and Seasons have been described. For critical discussion of term postformal thinking, see Kallio (2011). She claims that highest forms of adult cognitive development (as part of adult positive development) can be called as integrative thinking (i.e. integrating several different psychological domains as emotions, cognition etc.). A number of edited books were written on the topic of positive adult development in the 1990s (Commons,