Short answers, pulled from the story.
Milton Friedman released Essays in Positive Economics through the University of Chicago Press in 1953. The volume collected earlier articles written by the author over several years.
The lead essay titled The Methodology of Positive Economics contained core arguments defining the book's legacy. Friedman argued that economics should function as a science free of normative judgments to inform policy decisions objectively.
John Neville Keynes distinguished between positive economics and normative economics decades before Friedman published his work. Friedman adopted this distinction to separate what is from what ought to be in economic matters.
Paul Samuelson criticized Friedman's reasoning regarding the acceptance of false assumptions because it allows unscientific cherry-picking of results. He pointed out that this method shields assumptions from the requirement of explaining all phenomena.
Stanley Wong analyzed the F-Twist and its connection to Paul Samuelson's own methodology. Critics had long identified flaws in Friedman's approach by the 1980s according to historical records.