Tom Gilson over at Thinking Christian presented a post recently entitled "What is "Evidence" to Christians?" This post consists of my response to the ideas presented in the post as well as the ensuing debate found in the commentary on the blog.
First, the OP...Tom is more or less correct in my view when he defines evidence "as any information that would tend to lead a person toward a conclusion." He goes on to correctly say that evidence is not always necessarily a proof. This is important to understanding my critique of his evidences that he presents later in the post. All of the evidences listed are in fact evidences for Christianity, but they are not proofs for the validity of Christianity. I do not take issue with theists claiming that evidence exists for Christianity - the Bible does in fact exist, but I do take issue with theists that claim that the coalescence of these evidences implies a proof in any way, whether it be to the existence of God - specifically the Christian god, or whether it be the validity of Christianity. Claiming that "God exists" is a largely incomplete statement. It can either imply that God exists as a concept in the human mind or that God exists in some scientifically verifiable way. Notice the importance of the distinction. If you are claiming that God exists as a concept in the human mind then I'm pretty sure that you have plenty of evidence to your claim, even if that evidence is not direct physical evidence. But if you wish to claim that God exists as a verifiable scientific fact then you must provide direct physical evidence to support that claim due to the nature of what a verifiable scientific fact must be. A verifiable scientific fact must have some sort of direct physical evidence that supports its existence.
If it does indeed turn out that God exists merely as a concept buried within the human mind then God is subject to another distinction that it shares with all other ideas, namely, the concept of God exists because it was invented by the human mind. All other concepts that I can think of exist as inventions of the human mind at some point, and why should the existence of God be treated any differently? If it is to be treated differently then the burden of proof lies in the hands of the person making the claim. Proof in this sense can certainly exist without direct physical evidence if it is in the form of a philosophical proof. In all my years of reading the various philosophical proofs of God's supposed existence I have yet to come across one that didn't violate some rational precept in some fashion.
This is where I begin commentary on some ideas presented in the comment section of that blog post. Of course there is no direct physical evidence to the existence of the scientific method and thus science in general. Science exists merely as a concept in the human mind. It is a particular sort of concept in that we know that it is an invention of the human mind that allows us to better deal with our surrounding environment. That God can exist as a concept in the human mind is obvious, and in my view it seems reasonable that the human mind invented the concept of God in order to better deal with existing in its environment. Inventing something like God allows us to live with the fact that there are certain aspects of our own existence that we seem to not be able to know. As humanity's understanding of its environment has increased, God's supposed role in maintaining that environment has decreased to follow suit. God used to make the flowers bloom, not merely by creating them mind you...by actually reaching his invisible, divine hand down from Heaven to physically open the petals. Now even the most ardent fundamentalist Christian in my experience accepts that flowers bloom as a product of their design.
Later on in the commentary, the idea or morality is introduced. I hold that morals are a subjective concept. That people should not own other people is a moral concept that I hold to be true, but I hold it out of preference. It's a particularly strong preference mind you but a preference none the less. That humans should not be made to suffer at the behest of another human is once again a preference. I have no logical argument to offer against slavery or suffering that doesn't in some way hinge on my having a moral preference.
It is then brought up that the moral subjectivist cannot rationally attempt to negotiate his moral views with those that hold opposing views as they would simply be stating their preference on an action and then moving on. This both right and wrong to a degree. While it is true that if someone holds an opposing viewpoint to mine then I have no rational basis to attempt to get them to hold my viewpoint, but I can appeal to what I know of their moral ideas and rationally deduce an action close to the one that I wish to take place to which the opposing person should rationally choose to do.
Let me clarify this with an example. I have a preference to own and thus enjoy using a Sony plasma screen TV. Given that preference many logical courses of action come to mind, none the least of which is stealing the TV from a local vendor. My preference to own that TV is, however, super ceded by my preference to not impose suffering on another human being. Thus, it would be irrational of me to steal the TV, as satisfying my desire to own the TV will likely impose some undue suffering on the shop owner. It is on the grounds of the hierarchy of one's preferences that a rational negotiation can take place given any discourse. Another example; for whatever reason, John wishes to take a knife and jab it deeply into my forehead...a preference that will certainly lead to a great deal of suffering on my part. He states his preference, but he also states that he is willing to negotiate. I can negotiate with John on the grounds of examining his preferential hierarchies and searching for a point that acting on his preference of terminating my existence in this manner will lead to violating a higher preference, such as not going to prison. If John values stabbing me more than he values not going to prison then I can't negotiate with him on those grounds, but I could certainly attempt to find another point of conflict in his preferences. If it turns out that John values my demise more so than any other relevant preference then we would both have to rationally conclude that the best course of action would be to run me through. This conclusion would certainly be a difficult one for me to accept, but I can't claim that John is acting irrationally...he is merely acting to violate my preference of not being killed.
So how do we make laws? Laws are concepts created by humans in order to better live in our environment. Our survival as a species is made easier if we work together to gain mastery over our environment. Laws allow us to work together effectively. The validity of a law can be judged on the grounds of its ability to be enforced. Democratic process serves to take the moral preferences of the individuals of a society and create a maxim by which all of the members of that society will be expected to live. If a law violates the moral preferences of a significant proportion of the society to which it applies then that law will be difficult to enforce. Laws that are more universally accepted are usually easier to enforce. If a large enough portion of the populace does not support a law then democratic process will throw out that law. Notice too, that I am referring to the concept of democracy in general and not the specific "democracy" in which we are said to reside.
As for the Nuremberg trials are concerned, it may be true that the people in that trial responsible for laying down judgement did in fact appeal to an objective moral standard, but that fact doesn't prove that they did so in a rational manner. The obvious hypocrisy displayed in those trials can be seen upon examination of a quote made by Zach de la Rocha which goes something like, "If we held all of our leaders in the U.S.A. to the same set of standards that we held the people at the Nuremberg trials then every one of our presidents, from Truman onward, would be swinging from the gallows."