"popular assertion" is a valid and usable phrase in written English.
It can be used when describing a commonly held belief or statement that is accepted and shared by a large number of people. Here is an example of how it could be used in a sentence: "The popular assertion that breakfast is the most important meal of the day has been widely debated by nutritionists."
People have asked me why the president's economic advisers aren't telling him not to believe in the confidence fairy — that is, not to believe the assertion, popular on the right but overwhelmingly refuted by the evidence, that slashing spending in the face of a depressed economy will magically create jobs.
Asked how deeply his support extended beyond the Kremlin itself, he replied that his policies were popular among Russians, an assertion supported by recent polls.
It was a performance that felt freewheeling, contagious and delightful, with its ruminations on sex, the Daily Mail, and the assertion that popular culture "functions like a pink pony trotting through our brains shitting glitter".
The "claim of right" – an assertion of popular sovereignty – was endorsed by the Scottish parliament with the aid of Labour and Liberal Democrat, as well as SNP and Green, votes.
And while there was certainly an assertion of popular common sense in Newt Gingrich's weak fourth-place finish — it had looked, two weeks ago, like he might win — the role that unchecked Super PAC spending played in his defeat has to make one wary of what's to come.
In overturning that assertion of popular will, the Court no doubt realized it was setting the stage for a further confrontation in which opponents of gay marriage would try to override the Court's decision through the initiative process, this time amending the state Constitution.
Walter A. McDougall's assertion that 173,620 popular votes in Alabama should be subtracted from John F. Kennedy's popular total over Richard M. Nixon in the 1960 election is unconvincing.
In their June 3 response, the Dartmouth researchers called The Times's assertion that its popular maps do not reflect quality measures "false".
In terms of debunking stereotypes about South Africa, a good place to start is the assertion, contrary to popular wisdom, that "townships are not so dangerous".
Clearly that would be a controversial assertion, Pendleton being a popular part of the enormous success enjoyed by British cycling, a nine-times world champion who won gold medals at two Olympics.
