What is “evidence”? Every epistemologist (epistemology being the study of “how we know”) uses the word with great regularity, yet definitions or specific characteristics are difficult to come across. Evidentialism, that epistemological enterprise based on”evidence”, does not make the enterprise any clearer, using ambiguous terminology such as “quality” to determine the fittingness of evidence. How does one determine the quality of such evidence? By the explanatory power of the evidence? By some ineffable characteristic? Such a question does not have a solid answer, other than placing an “obligatory” status on “good” evidence.
Given that the ability to determines what constitutes knowledge remains in question, the quest for evidence would seem an inextricable part of the process, something explicated in a more precise and rigorous fashion. An essential element of evidence, in the view of the author, suggests that it provides justication to a belief in some way, but not an involuntary obligation. Whenever a belief is formed, any epistemically viable belief must have information, data, or something of the like to apply to that belief that constitutes its “evidence”. However, simply equating “evidence” with “justification” appears a losing proposition – what counts as evidence? What must be the quality, quantity, or strength of the evidence that converts the belief from epistemically viable to epistemically invalid for an individual without falling into arbitariness?
To solve this requires a sort of general rule: barring a simple explanation, evidence varies by context, the belief and believer in question, and to what degree the evidence affects the strength of the belief. Such a wide ranging use allows for “rules”, so to speak, in
regards to evidence usage and formation that, in any case, draw the enterprise ever closer to understanding what brings one to knowledge as a publicly accessible enterprise.
Thus, the question remains: what is evidence, what constitutes it, and what gives it warrant? Perhaps this question finds its best answer in everyday contexts, as its use makes its actual character clear. Within either a particular set of rules, such as in a courtroom setting,
or within a particular context, such as forensic analysis, evidence is whatever is considered “evidence” in that context. In the case of a courtroom, only empirically veriable information works as evidence; eyewitness testimony is usually tested on the strength of the physical evidence rather than the testimony per se.
However, normally formed “beliefs”, as it were, are not so simple when it comes to what constitutes sufficient evidence for an individual. A belief in God, for example, requires a vastly different criteria for the atheist skeptic (mainly empirical) than it does for the believer (mostly experiential); however, the former presents public evidence to amass public support for his own decisions, while the believer uses life experience as his/her main criteria. Clearly, both are operating under different premises when making the investigation, and that is a problem.
More to the point with an example: a Christian and an atheist, both biologists, view a platypus.
The fascinating and frankly odd looking creature has a combination of characteristics, seemingly derived from various animals, such as a beak, a beaver tail, webbed feet, and the ability to lay eggs that all work in ways ill-befitting the common classification “mammal”. Thus, both seek to uncover how this creature came into being in the natural world – i.e., what is its ultimate cause? Both have the same tools of observation and classication; thus, their analysis becomes incredibly similar. However, in terms of “what caused this to come into being”, the answer relies on the starting premise. The observations, in that sense, are theory-laden from the get go.
The former, of course, describes the creature in glowing terms. “This is fascinating! Only God could have created such a creature”, he says. Even though he holds the knowledge of evolutionary biology in his mind, the ultimate explanation is supernaturalism, whereas evolution was the means to get to that end. The aesthetic, experiential portion of observing the platypus supercedes the empirical evidence of the platypus’ evolutionary characteristics. He has all of the same empirical evidence as any biologist would in this case, yet he still
attributes the animal’s existence and uniqueness to some unseen, empirically unverifiable force.
The total evidence, then, is not restricted to empiricism alone. The belief already assumed by the observer explains the problematic nature of the platypus’ unique appearance and function. On the other hand, the atheist biologist will not accept that it came from an unseen force, something akin to magic; a physical explanation, like evolution, has reams and reams of empirical data that can explain how the platypus came into being. Evolutionary explanations, on this end, are intellectually satisfying for the atheist.
In neither case was the result really different except for an obvious difference in epistemic criteria. One might say that the total evidence of both cases actually remains the same, but the interpretation of that evidence differs vastly. For one, evolution explains the process
but not as ultimately sufficient, requiring augmentation by religion; on the other hand, it is overwhelmingly sufficient for explanation in and of itself. In both, what constitutes evidence, and to what end, is entirely up to the individual. For the Christian, a particular belief (in God) is believed as properly basic like in the Plantigan model, hence allowing empirical, aesthetic, and experiential evidence to constitute evidence for God’s creation of the platypus. In the atheist version, empirical data alone does the work as a source of justification or warrant for the formation of the platypus, much of which is contextually derived and developed.
This, then, is the problem: the “evidence” that forms beliefs seems, in some cases, to be based around beliefs already held by the person in question – in other words, they supervene on presuppositions of the person. We could also state that both use an inconsistent criteria,
but that is not necessarily the case; either might hold their beliefs are completely consistent, but the evidence itself varies wildly – it is “picking and choosing”. As Conee and Feldman state, the believer’s beliefs must rest on the evidence available to them, even if that evidence is not necessarily sufficient or they do not have the necessary cognitive faculty to recognize this fact. Thus, it appears “evidence” depends on the kind of epistemological commitments one has already made. That also entails that the normative facts that one is justified in believing do not necessarily supervene on evidence. Surely, if the evidence is identical to both, why is it that both do not come to the same conclusion?
Certainly, one could say that the scientic, empirically based explanation is vastly superior, but that would simply assume that the presuppositions of science entail what beliefs find justification or warrant. In either case the justication appears to work in an foundational internalist way, relying on a properly basic belief (or set of beliefs). Is this really the case for all evidence, though? Locke, for example, believed that the prime epistemic duty of a person is proportioning the degree of beliefs to evidence, specifically that data and information which is certain of me. Does the individual deserve the right to determine what constitutes proper evidence?