Just as there are no convincing arguments for the existence of a thing outside of experience that causes experience there are no convincing arguments for there not being a thing outside of experience causing experience. It’s quite ironic that one of the most basic of claims (that there is a reality external to and independent of us) turns out to be metaphysical! That is metaphysical in the sense that the logical positivists and empiricists meant the term: something that is outside of experience and therefore unknowable.
I believe it is because of things like this that a lot of the popular scientists (such as Richard Dawkins and Neil deGrasse Tyson) denigrate philosophy. They don’t want to be caught with their pants down so to speak and the questions philosophy asks put them in this embarrasing predicament. Questions such as “What distinguishes between a scientific theory and a non-scientific theory (aka the problem of demarcation)?”, “If all propositions are verified via experience what can we do to proove there is a reality independent of experience that causes experience?” and “Why do you have experience and consistency as criteria for verification?” all show us that the scientist is just a man!
To talk about something significantly different…
There is the argument for the existence of an external reality that goes along the lines of “Well everyone believes this to be so! If we didn’t we’d murder people and all sorts!”. First I don’t believe this is the default opinion. It may appear to be the default opinion in the west but there are many eastern traditions in which people from very young ages will express the belief that appearance is an illusion that hides nothing. The so called “Default position” is really just an expression of social conditioning! It’s the same with common-sense; common-sense is different in different cultures because it is nothing but the sub-conscious opinions people pass on to one another. It is common sense in England not to poo in your water source; in some lesser-developed countries there are huge campaigns to get people to stop shitting in their drinking water! For example!
As to the idea that people would behave immorally if they didn’t believe that what they experienced was caused by something indepentant of them that’s clearly falsified by the hundreds of thousands of prison inmates most of whom would declare their belief in an external reality and scorn the very idea of questioning such a thing.