Which of the following...?

My first response to your question would be to clarify the terms. Your definition of naturalism is generally the one I use, although the specific sentence that naturalism sees the scientific method as the “only effective way to investigate reality” sounds a little more like scientism than naturalism to me.

Scientism would of course phrase the role of science like this:

"The scientific method is the only way to the truth."

My major problem with this position is that it is based on a metaphysics that renders itself useless. To say that science alone can get us to the truth is a truth statement that cannot be scientifically tested. It is a metaphysical statement. If it were true, it would render itself useless since as an unscientific statement it cannot be true... It's a classical paradox.

But you go on to specify that naturalism as you define it does not necessarily deny the existence of the supernatural, but that hypotheses of the supernatural are best studied applying scientific methods. The major problem I see here is the same problem that Heidegger pointed out when he discussed historicism. Like historicism, the natural sciences have come to accept the fact that human understanding is historically conditioned. As folks like Kuhn, Feyerabend and Lakatos have worked out, the way we interpret reality scientifically is largely dependent on our historical background, and in particular affective history (where the interpretation of an historical event is affected by the historical event itself). In other words, understanding is not always best captured by a method that while accepting the historical condition of our understanding tries to circumvent the problem by making timeless, i.e., a-historic claims. Heidegger called the method historicism suggested the quest for a foothold where there is non. Once again, we face a paradox: if we are historically conditioned in how we know, assuming that there are methods that are independent of historical condition is somewhat of a contradictory assumption…

I think the scientific method is absolutely helpful and provides us with that part of an interpretation of reality that Paul Ricoeur called “explanation.” For Ricoeur, however, explanation – using critical methods to investigate reality – cannot be the whole interpretation, since it ignores our preunderstanding, which is historically conditioned and which we bring to every phenomenon we interpret. True new understanding, so Ricoeur, and I agree, emerges only from the dialectic of preunderstanding and explanation.

In other words, the scientific method is indispensable for investigating reality, but alone not enough. It is necessary, but not sufficient.

What then about supernaturalism? Well, once again my concern is its definition, which this time you don’t give. Without trying to put words in your mouth let me suggest a very general definition of supernaturalism as “a believe in subsistent reality that transcends nature and which can therefore not be investigated using the scientific method.” The main problem here is not the thought that there can be something that goes beyond nature, but rather how we can think of the supernatural without moving into dualism. As long as dualism is avoided, I can’t see any problem with notions of the supernatural – except for of course the obvious, namely that one does not believe in it. But that view is of course based on faith just as the belief in the existence of the supernatural.

To summarize then, I think that naturalism is highly problematic and that supernaturalism, if properly cast, is far less problematic.

I think i'd agree with oputz that stating that the scientific method is the only or best method for investigating reality is inherently problematic.

However, this is the same problem that logic suffers from - you cannot establish it as being a valid investagatory method except by using it to validate itself, which just does not follow. It is effectively an article of faith ("I believe that the scientific method is the best one for investigating the universe").

That said - I have yet to hear of any acceptable suggested alternative.

Faith-based methods for classifying reality suffer from a worse problem: they are never validated, because validation requires evidence, which is not part of faith.

I'd say that neither is more fundamentally incorrect than the other, but that supernaturalism is just less *useful* in many instances.

Before I can answer this question intelligently you'll need to define both "naturalism" and "supernaturalism." What do these words mean? Are they some kind of religious belief?

Well, I guess it takes all kinds to make the world go 'round. Personally, I could care less which is which. However, to answer your question, I think both are legitimate entities. I've seen the natural, but I've experienced the 'supernatural.' They are both real, but with different functions.

Which one is least like existentialism. That will be the more incorrect.