There is no default position. You are just creating one for yourself.<quoted text>
I got to thinking about this a bit more. Of *course* absence of evidence is evidence of absence. It may not be *conclusive* evidence of absence, but it certainly is evidence. Furthermore, why is it not conclusive? Because you may not have looked in the correct places, or with the correct means, etc. But if you have looked extensively, and by a variety of means, then the prolonged absence of evidence *is* evidence of absence that increases in quality for each new way of looking and number of times looked.
As an example, there is a law of physics: the law of conservation of mass/energy. The absence of evidence that this law is violated after many and repeated attempts (perpetual motion machines, for example) is, in fact, evidence of absence. Given the number of ways we have looked and the strictness of the law (hence the high degree of testability), the prolonged absence of evidence of violations is very, very good evidence for that law.
So the question then becomes at what point does absence of evidence become strong evidence of absence? Well, we have to have searched in many different way and over a long period of time. We have to have searched in ways that, if the existence was true, we would have found evidence.
So, lets do this: what precise search method that is public and independently verifiable will lead to the detection of a deity? This method should give a different answer if there is no deity than if there is one (or many) and should be such than even an unbeliever will be able to observe the evidence as unambiguous evidence of existence.
If no such method exists, then the default position is the non-existence, just like it would be for Bigfoot, a supersymmetric particle, or an elephant in my room.
How would a tuna search for an agave plant? Agave plants don't exist for a tuna. But an agave may see a tuna and knows it exists.
As far as deities go, you have human beings that say they can feel the presence of one, or more. Lots of humans, actually. So there is a link to somewhere beyond what you can physically sense. You just ain't found it.