The phrase "a mere assertion" is correct and usable in written English.
It can be used to describe a statement that lacks substantial evidence or is considered trivial.
Example: "His claim about the project's success was nothing more than a mere assertion without any supporting data."
Alternatives: "a simple claim" or "just a statement".
In addition, Kant argued, when we are gazing at an object, we do not consider its beauty a mere assertion of taste; we do not emphasize the relative aspects of our experience, like the cultural moment or our mood.
What needs to be accomplished is more than a mere assertion of (3), based on knowledge of one's hands.
As contraries, Chris is happy and Chris is unhappy allow an unexcluded middle, since Chris can be neither happy nor strictly unhappy; similarly, I don't like him is generally understood as stronger than a mere assertion that it's not the case that I like him.
A mere assertion by the decision-maker that a matter involves national security does not preclude the court's judicial function of determining whether the decision was in fact based on grounds of national security.
This is not a matter of mere assertion on principle; it is based on massive amounts of repeatable observation (Calabrese and Baldwin, 2003; Calabrese and Blain, 2005; Cohen, 2002).
Moreover, an Indiana resident's mere assertion that he shot a police officer because he thought the cop had entered his home illegally and presented a threat doesn't necessarily get him off the hook.
The mere assertion of a laudable governmental purpose, of course, should not immunize a race-conscious measure from careful judicial inspection.
Can the Executive order the assassination of a U.S. citizen without first affording him any form of judicial process whatsoever, based on the mere assertion that he is a dangerous member of a terrorist organization?
(The judge noted the case raised questions about whether the president could "order the assassination of a U.S. citizen without first affording him any form of judicial process whatsoever, based on the mere assertion that he is a dangerous member of a terrorist organization". But he dismissed the case, saying Mr. Awlaki's father did not have standing to sue).
Judge Bates acknowledged that the case raised "stark, and perplexing, questions" — including whether the president could "order the assassination of a U.S. citizen without first affording him any form of judicial process whatsoever, based the mere assertion that he is a dangerous member of a terrorist organization".
In October, 2005, at an advertisers' conference in Phoenix, Bill Keller complained that bloggers merely "recycle and chew on the news," contrasting that with the Times' emphasis on what he called "a 'journalism of verification,' " rather than mere "assertion".
