Strict rationality will never work as a philosophy in this universe for a few reasons.
The first is that there is no reason to undertake (or to fail to undertake) an action using a strictly rationalist framework. All of this at the human level requires morals, ethics, values and desire. Even at the animal level, choices must be made. Decisions depend always on more than mathematical calculations of utility or gain maximization.
The second is that there is no path from and never will be from particle positions and velocities to meta behavior. Possible in principle? Perhaps. But combinatorial explosion means that it’s a path we can never walk in practice to travel mathematically or rationally from the very small to the very not. It simply cannot be done. Thus no rationality because predictive power will always be minimal or at least far less than expected in any real-world system.
The third and more important is that the evidence that the universe itself is rational is not so clear as the empiricists would like you to believe. First, ignore the mumbo-jumbo dispensed by the quantum mysterians, believers that the universe is a simulation, Schrödinger’s damn cat or the usually-wrong statements about Gödel’s Incompleteness Theorem. You don’t need any of that. All that is required to conclude that the universe lacks rationality is to simply believe as the empiricists demand that the universe is completely deterministic.
Believing this, then ask yourself if the universe is in fact fully deterministic, how can causality possibly work or have any meaning at all? If there is no choice, no volition anywhere in the stack (which is what determinism absolutely and inviolately demands), then everything that follows from causality is illusory: particle interactions, atomic configurations, choices, decisions, predictions, relations between anything and anything else (just another name for causality). Nothing can be said to have caused anything else because from the very first moment of the Big Bang (and perhaps before) it was preordained — coded into the universe as in a computer program. (Does causality make sense in a computer program? Nope! See above.)
In other words, causality and determinism are irreconcilable but both are at the heart of scientific enterprise. This is not some trivial objection. It is a fundamental failure that cannot be hand-waved away nor denied no matter the anguished screams of empiricists everywhere.
