The phrase "a certain proof" is correct and usable in written English.
It can be used when referring to a specific type of evidence or demonstration that confirms a claim or theory.
Example: "The scientist presented a certain proof of the theory, which convinced the skeptics in the audience."
Alternatives: "a definitive proof" or "a specific proof".
I can hardly imagine to myself a more distinguishing mark, and, consequently, a more certain proof of design, than preparation, i.e. the providing of things beforehand, which are not to be used until a considerable time afterwards; for this implies a contemplation of the future, which belongs only to intelligence.
While the Supreme Court declared in 1983 that such an acquittal was certain proof of dangerousness, that was largely wrong as well.
This was taken as a positive development — other polls had put the gap at 24 and 37 points — and as certain proof, in a season like the present one, that anything was possible.
During the latest suspension period, mortgage buyers and some lenders said those seeking to buy homes in flood zones could still get a mortgage as long as they provided certain proof that they had applied for flood insurance.
In the two first named Averroës stakes a bold claim: only the metaphysician employing certain proof (syllogism) is capable and competent (as well as obliged) to interpret the doctrines contained in the prophetically revealed law (Sharʿ or Sharīʿah), and not the Muslim mutakallimūn (dialectic theologians), who rely on dialectical arguments.
They conceive that it would represent the devil's most cunning attempt at self-camouflage to be demythologized and that camouflage would be a certain new proof of his existence.
I had not chosen her friendship; it had been imposed upon me .Janet Flanner, writing in the New Yorker in 1956, dubbed "A Certain Smile" proof that Sagan is "a born French novelist of style & quality, whose performance is unconnected with her calendar".
An appeal filed on his behalf was dismissed in 2002, when the court of appeal ruled that DNA analysis of fabrics recovered from the scene of the murder of Michael Gregsten and rape of Valerie Storie in 1961 provided "certain proof" that Hanratty was guilty - a claim still challenged by his family and campaigners.
A generous helping of sushi-standard spicy tuna was spread across vast swaths of bread and topped with an unrecognizable frizzle of scallions, like giant Japanese bruschetta — certain proof, if you needed it, that the eighties are back and better than ever.
Nissen's technique of measuring plaque with ultrasound would allow a faster path to approval, but until now there has been no certain proof that affecting plaque buildup helps patients.
