How to beat a presupp at their own game

[vulcanlogician]

To fellow atheists, somewhat different question - but a question I often see from theists. The question goes : where do atheists get their basis to justify any claim they make?

There is a whole field of philosophy devoted to this. It's called "epistemology." It is a matter of rigorous debate upon what basis we have knowledge.

A pretty solid theory is correspondence theory. It says that knowledge is a "justified true belief." 

So let's take something simple: "I know that my coffee mug is sitting on the desk in front of me." (This is genuine knowledge that I have. What makes this knowledge genuine? It's a justified true belief.)

Justification: I see it there. I just picked it up and set it down. Sense data corroborates that my coffee mug sits on the desk in front of me. That's pretty good justification.

True: The coffee mug really has to be there for my belief that it is there to count as real knowledge. If it WASN'T there, then my belief that it was there wouldn't be genuine knowledge (duh.... obvious but must be stated.)

Belief: I have to believe that the coffee mug is on my desk to have genuine knowledge of its being there. (It's another obvious "duh" thing that must be pointed out. If I DID NOT believe the coffee mug was on my desk, it would be impossible for me to have genuine knowledge of its being there.)

It's not perfect. It's not air tight... but it's WAY better that what Darth guy says. And it actually addresses the issue of what genuine knowledge might be in a very realistic and natural way. When a normal person considers what the foundations of knowledge are, they don't normally look for some otherworldly answer. They REALIZE that they know some things. They just want to make an honest inquiry into HOW they know.

Looking at things like the justification and the truth of a belief is a MUCH better approach that appealing to a religious construct.

His reasoning is that in a godless world, there is nothing absolute and ultimate to ground all possibility and impossibility.

How so? Who says there is nothing "absolute and ultimate" in a godless world? Just because there is no god, that doesn't mean there isn't some other absolute and ultimate thing that isn't a god.

It's a universe based on chance, so the laws of physics may change tomorrow. Also, his argument is that all facts and knowledge in a godless world are arbitrary, whereas in his worldview knowledge can only be attained through the Christian God because he is omniscient and all-powerful and institutes that which is fundamental and ultimate etc, etc.

Too bad this "Christian God" is so stingy when parsing out knowledge to his followers. If he wants to say a believer's knowledge is somehow better than a nonbeliever's, he has his work cut out for him. And for all we know, the laws of physics might very well change tomorrow. We have no knowledge of whether the laws of physics have changed except scientific observations which say that they were probably constant since the beginning of the universe.

This guy is just posturing. I get the impression he doesn't really care what genuine knowledge is. The truth is: the ultimate foundations of our knowledge are debatable (ie. not exactly clear). This is god of the gaps coming in to do the job because Christians can't go around saying "God must make the sun rise" anymore.