"evidential foundation" is correct and usable in written English.
You can use this phrase to describe a basis for an argument or position, usually based on evidence or facts. For example, "The evidential foundation of my argument is based on ten years of research findings."
After an inquiry, Lord Carlile, the terrorism legislation watchdog, said that none of the arrests had been made "on a full evidential foundation", and that "the authorities had no specific information as to where the suspected terrorist event was to occur, nor any precise knowledge as to its nature".
What they share is a desire to provide a scientific, evidential foundation for important decisions related to human conflict and its consequences.
Justification may have foundations but only because we end a regress of justification with propositions that are known the evidential foundation on which all justified belief rests is knowledge (186).
In cereals at least, we suggest that this preference rests on a weak evidential foundation.
At the inquests, lawyerly detail was focused on the few, startling internal documents produced by the force from 2010 in the public disclosure process to the Hillsborough Independent Panel, evidential foundations for the projection of blame.
There is no evidential basis in that statement at all".
Gott's evidential base is a disconcerting mishmash.
What evidential basis lies behind the highway code is a matter for the Department for Transport.
Where estimates are used, they should have some sort of evidential basis and be current.
Traditionally, epistemology has been construed as a normative project whose aim is to clarify and defend conceptions of knowledge, foundations, evidential warrant and justification.
("Logical Foundations of Evidential Support," (Fitelson 2006a) is a good example of the genre).
