Why Biblical Inerrancy?

According to some systematic theologians it is. I made a thread about this a while back.

I do think there is a valid point in there somewhere. God is the highest authority, We cannot appeal to some other authority to prove this as that would invalidate God as our highest authority. But at the same time, isn’t Grudem using reason when he says the Bible is self attesting and argues thusly? Are we not all slaves to reason by default? I’m not philosophically knowledgeable to get out of this pickle but it raises some interesting issues.