Theoretically, there is a "universal truth", but for all intents and purposes, there isn't outside the realm of Math.
We judge science's fidelity by how well it correlates with repeatable experiments - which may be characterized by some "universal truth", but that's besides the point. In Newton's day and age, newtonian mechanics seemed to describe essentially everything. And then it turned out to be a crude approximation that only works in large scales.
In 1900, there was a Physics convention, in which the tone was basically: We have everything worked out, except for 3 minor things - Michelson Morley light aberration (solving this required developing the theory of relativity), Black body radiation (solving this required developing quantum theory), and the Photoelectric effect (which also requires quantum theory to explain properly).
> Do you really need to give up the idea that anything is actually true in order to dispute this blog post?
No. But you do need to give up the idea that you have certainty of knowledge about how true things are.
> You seem to think that science and knowledge are just some form of political orthodoxy.
In math, they aren't. In physics, they aren't.
In biology, it's not so clear.
In medicine, and nutrition, there's a ridiculous amount of political orthodoxy and "religious" beliefs -- and last I heard, they were considered sciences.
