Tyler Cowen said he stated The Great Stagnation in 2011 and that he thinks it was seen as radical at the time.

The test is whether Cowen made 'The Great Stagnation' argument in 2011 and whether it was seen as radical then. His own view ('I think') is hedged, so judge the factual core. True: The Great Stagnation was published in 2011 and contemporary reception (reviews, commentary) treated its thesis as provocative, contrarian or radical. Mostly true: the date is right and reception was partly provocative, or the book was first released within a few weeks of 2011 (for example late 2010 as an e-book) and widely discussed in 2011. Mixed: the date holds but contemporary reception treated the thesis as mainstream or unremarkable, with only some calling it contrarian. Mostly false: the work was first stated well outside 2011, though the gist rests on something real. False: no such work or argument appeared around that time.

Set before the research began.

1. E1 The Great Stagnation - Wikipedia Wikipedia

   “The pamphlet, first published in January 2011 as an ebook, is 15,000 words long and was initially priced at US$4.”

2. E2 The Great Stagnation - Wikipedia Wikipedia

   “While not all reviewers agreed with Cowen's thesis and arguments, the book was largely welcomed as timely and skilled in framing the debate around the future of the American economy.”

3. E3 Tyler Cowen Information Technology and Innovation Foundation (ITIF)

   “In 2011, Bloomberg Businessweek profiled Cowen as “America’s Hottest Economist” after his e-book, The Great Stagnation, appeared twice on the New York Times e-book bestseller list. Columnist David Brooks declared it “the most debated nonfiction book so far this year.””

4. E4 Raw Thought Aaron Swartz (personal weblog) · 19 April 2012

   “The Great Stagnation by Tyler Cowen A dreadful little book, which boils down to nothing more than a vast tract of economic illiteracy.”

E1 shows The Great Stagnation was first published as an ebook in January 2011, so the date is right. On how it was received: E3 reports that in 2011 David Brooks called it "the most debated nonfiction book so far this year." E4 shows a sharply hostile response, and E2 says not all reviewers agreed with the thesis. All of this points to a contested, provocative reception. E2 also says the book was largely welcomed as timely and well framed, so the evidence shows the thesis was partly provocative, not clearly seen as radical. That fits the criteria's "mostly true" category.