Questions such as these have a mind-numbing quality; they have a tendency to paralyze thought.
Why? Is there a better way to consider the nature of matters such as "evidence" and "proof"?
Perhaps questions of the form "What is ... [some thing or phenomenon in law]?" induce mental or intellectual paralysis in part because such questions incline the observer to launch a search for attributes which, when properly assembled and arranged, could constitute -- the observer may hope -- a correct or adequate definition of a phenomenon such as "evidence" or "proof." If a non-solipsistic observer conducts a non-circular search for the attributes of a (complex[!]) social(?!) phenomenon such as "legal evidence," (s)he is likely to generate a very long list of attributes. Such a list of features may end up being a mere aggregation of attributes that resembles a serving of thick porridge unaccompanied by any explanation for the identity or quantity of the ingredients found therein.
I do not wish to overstate my objection to starting discussion of the law of evidence with a definition: it is unlikely that conceptual mush is an inevitable effect of launching an investigation with a request or search for a definition. I only wish to suggest that acquiring an understanding of the nature of a legal phenomenon or practice such as the law of evidence is not best promoted by formulating and then pondering assertions such as "legal proof is an epistemic process," "judicial proof is a legal process" and "judicial proof is a symbolic process," and that the search for an understanding of a matter such as legal proof is better promoted by formulating topics of discussion in the following fashion: "scarcity in proof," "time in proof," "evidence in legal proof," "argument in legal proof," and so on.
A restatement of the general question under discussion in this post:
Is it fair -- or is it instructive -- to begin a discussion of the law of evidence or proof with a definition or definitions of matters such as "evidence" or "proof"?A tentative answer to the (reformulated) general question:
A question such as "What is [legal] evidence?" is in part an empirical question: unless one is a Platonist -- or unless one denies the possibility of social variation --, a good answer to such a question always requires in part an account of what is conventionally considered to be a thing such as evidence.True, a definition of phenomenon such as "evidence" or "proof" should not be a mere catalogue of the matters that are considered "evidence" or "proof": a good definition crystallizes a wide diversity of phenomena; a good definition resembles a rule that generates or explains (perhaps only by and large) a wide and diverse collection of phenomena that might be considered instances of a matter such as "legal evidence." But it does not follow that one ought to begin a scholarly discussion of a legal field such as the law of evidence with a rule or formula that (putatively) specifies the essential or important attributes of a matter such as "evidence" or "proof." It is probably better instead to proceed quasi-empirically and quasi-inductively: judgments about the important or "essential" attributes of matters such as "legal evidence" should emerge out of ruminations based on our observations of the real-world workings of matters such as "the law of evidence" or "proof in legal proceedings." (Such ruminations may, but need not, devolve into bare quasi-statistical statements of the relative frequency of various attributes in a process such as "proof in legal proceedings.")
N.B. Is it not the case that for some purposes -- including the present one -- a good "definition" of a social phenomenon and practice such as "judicial proof" must include an account of the motivation(s) for the phenomenon or practice? (Construe "motivation(s)" broadly: make it encompass "function(s).")Postscript #1: Definitions -- properly and broadly understood -- are important. One needs them to understand the spirit of a social phenomenon or practice that, because of its variety and diversity, may otherwise seem bereft of rhyme or reason.
Postscript #2:The ruminations in this post are intended only for (actual or aspiring) authors of legal texts. (These ruminations are, in any event, unlikely to interest anyone else.)