In our day to day lives, we do not require that propositions be proven to us with absolute certainty before accepting them as true.
If we did indeed live that way, we would never get anything done. We would not even be able to get out of bed, for before we moved to get out of bed, we would require some sort of empirical proof that when our feet hit the floor that we would actually be able to stand.
We would not be able to brush our teeth, for before we put the toothpaste in our mouth we would require some sort of absolute proof that the toothpaste was in fact toothpaste and not some sort of white toxic poison.
We would not be able to have our morning coffee because before we did, we would require some sort of absolute proof that it was in fact coffee and not some poisonous black liquid that smelled and looked and tasted just like coffee.
We would not be able to drive to work because we would require some sort of empirical, testable proof that when we turned the key in the ignition switch that the car would not malfunction and blow up but would rather simply start the engine to running.
We would not be able to commute, because we would not be absolutely certain that the drivers in on-coming traffic would stay in their lane and not come crashing head on into us.
All of these things we take for granted for various reasons. In other words, we trust that the coffee is coffee, that the toothpaste is toothpaste and that drivers will for the most part not kill us in head on collisions even though we can not be absolutely certain about these things.
It is evident by the way we live our lives that we take much more for granted than what we maintain we do in philosophy forums.
Over time, we recognize certain patterns in reality. We take these patterns for granted i.e that these patterns will continue to hold as they have in the past. This is how our reasoning is carried out in our everyday lives. For the past 10 years I have put keys into the ignition switches of cars and turn them causing the engine to crank. For the past 10 years I drink coffee every morning and it has been coffee for the past 10 years so I assume, take for granted, infer that it will be coffee tomorrow. This does not necessarily mean that it will be coffee tomorrow, but I can be pretty sure beyond a reasonable doubt. That is all I need.
We observe cause and effect without fail in our everyday lives. This is how we reason.
So when it comes to Santa Claus, I simply do not need empirical proof that Santa Claus does not exist to maintain that he probably does not exist.
Of course, he may actually exist somewhere, but the mere logical possibility that he exists in no way can be used to argue that he does indeed actually exist when we have good reason to think he does not.
We have no evidence that a fat old white man who wears a red suit can actually fit down people's chimney's. We have no evidence that he has a special type of craft that can be pulled by special reindeer who can fly that can traverse the entire globe and visit the billions of children in the world in one night.
So, it seems to me, that just because we cannot empirically prove that santa does not exist, that in no way prohibits me from making the statement: "Santa Claus does not exist" and that statement be true beyond a reasonable doubt.
Since none of us live as complete and total skeptics about reality, but take many things in our everyday lives for granted and feel justified in doing so, we should not pretend to be complete skeptics when it comes to certain philosophical subjects and topics.
We can debate all day and argue back and forth on whether the non-existence of something can or cannot be proven, but the question is:
"How do we live our lives?"
If we all live as if Santa Claus does not actually exist (I hope no grown adult who posts on these forums when it comes Christmas eve is actually out on their rooftop in the cold winter with a video camera hoping to catch a clip of an actual man riding in a sleigh pulled by flying reindeer), then why do we discuss his existence or non-existence so much in philosophy forums? It seems that our actions speak louder than our words.