Like I mentioned elsewhere in this thread, the "No Universally Compelling Argument" post you site applies equally well to physical and even mathematical facts (in fact that was what Eliezer was mainly referring to in that post).

In fact, the main point of that sequence is that just because there are no universally compelling arguments doesn't mean truth doesn't exist. As Eliezer mentions in where recursive justification hits bottom:

Now, one lesson you might derive from this, is "Don't be born with a stupid prior." This is an amazingly helpful principle on many real-world problems, but I doubt it will satisfy philosophers.