In his speech, he encourages others to follow his lead, rejecting the focus on what he calls “parsimonious modeling” inspired by Friedman. Everyday experience and observation must be returned to a prominent place in the profession, he argues.

“The early Keynesians got a great deal of the workings of the economic system right in ways that are now denied,” Mr. Akerlof said in a study newly posted on the Internet that closely tracks the text of his speech. “They based their models, as Keynes put it, on ‘our knowledge of human nature and from the detailed facts of experience.’ ”

A lot of what Mr. Akerlof advocates in his speech is already under way, with Mr. Akerlof himself a major contributor. He shared a Nobel in economics in 2001 for his work on imperfect information, concluding, for example, that economic outcomes are altered when a used-car salesman knows more about the condition of a vehicle he is selling than the buyer. It was an imbalance that helped to produce state “lemon laws” that protect buyers.

He was an early participant in behavioral economics, another assault on the rational, fully-informed behavior that Mr. Friedman counted on to make markets work efficiently without regulation or intervention.

People often do not behave rationally, the behaviorists found in their experiments. Most do not bother to sign up for a voluntary 401(k) plan, for example, but do not pull out of such a plan if an employer signs them up automatically.

Now Mr. Akerlof is taking a big step on his own. His speech is based on more than a year of research, much of it done with Rachel Kranton, a University of Maryland economist. They are trying to incorporate into theory, as Keynes once did, the great variety of “norms” that determine human behavior.

What Mr. Akerlof is trying to do, with Ms. Kranton’s help, is to reflect the variety of motivations that come from the sense people have of “what they are and how they should behave,” as Ms. Kranton put it.