You can't interpret any fact without an internal model of how the universe works. That model is a "side" and compared to any other model, has a difference calle

You can't interpret any fact without an internal model of how the universe works. That model is a "side" and compared to any other model, has a difference called "bias". There is presumably one true model that matches reality best. You could call that "unbiased", but since nobody can reliably identify it, we're stuck with bias.