Much needs to be said about the proper role of evidence in philosophical and theological discussions. People seem to have a notion about evidence that requires near-certainty, or that in order for something to count as evidence it must be found convincing to them. Specifically, I have heard lately “there is no evidence for such-and-such in the Bible.” When it comes to major theological issues within Christianity, it is rare that an espoused major opinion has absolutely no biblical or theological evidence. We should discuss the proper definition and role of evidence.
Some fact F serves as evidence for a proposition P just in the case that P is more probable given F’s truth than if F had not been present. Some F does not serve as evidence for P in the case that P is just as probable given F’s presence as its absence, or in the case that P is actually rendered less probable given F than not-F. Here’s a real world example:
Suppose I arrive home to discover my wife Jodi’s car parked next to my house (F1). I now have reason to think Jodi is home (P), because her being home is more probable given that her car is parked at the house than if her car were not so parked. So F1 is evidence for P. Now suppose we say, almost without exception, Jodi’s car is driven only by her (F2). So F2, taken with the fact I see Jodi’s car (F1), is evidence for P. This shows the role of evidence is to take in all relevant facts to confirm or disconfirm a proposition.
Now for a twist: suppose I suddenly remember Jodi is out of town this week (F3). F3 thus serves as evidence against P, for P is less probable given F3’s presence than it would be in the absence of F3. In fact, F3, on its own, is stronger than both F1 and F2; it is strong enough to act as a defeater for P. Perhaps it is the case I left the car there and took her to the airport. However, it does not follow that there is no evidence for P.
The same goes with respect to theological debates. It may be we have sufficient evidence to reject a premise, but it doesn’t necessarily follow therefore there just is no evidence for that premise. The problem of evil acts as evidence against God’s existence; Christians (such as I am) just think the evidence for God outweighs this.
This brings us to the role of evidence, already implicit. Evidence and relevant facts ought to be amassed in order to evaluate a proposition. This does not mean one must know everything there is to know about a subject. I would submit that if there is enough evidence relevant to the situation or premise that one can assert, tentatively, that the evidence points in favor of the proposition. There is much offered in the realm of evidences for (and some against) God. One should only remain agnostic in the event she holds her evidences in favor of and against God to be precisely equal! This is the definition and role of evidence.
 Indeed, even the existence of evil may itself serve as evidence for God’s existence, given other introduced facts.
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