Our most solid knowledge knows itself to be revisable.

Look at how science proceeds, our most reliable form of knowledge: it lays down no untouchable dogmas, it puts forward theories and exposes them tirelessly to the test of the facts.
When a theory fails, it is corrected or replaced: Newton's mechanics, long held to be definitive, gave way to Einstein's, without knowledge collapsing for all that. It progressed.
Such knowledge is therefore neither a dogma nor a doubt: it holds its best results to be true as far as can be established, while knowing them revisable. Revision is no weakness here, it is its very method.

Therefore So one can know in earnest without claiming definitive certainties: is no soft compromise, it is the very attitude of our surest knowledge.

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Deepenings

Conjectures and refutations

made it the heart of his philosophy: a scientific theory is never proved once and for all, it is offered as a bold conjecture that one then strives to refute.
What distinguishes a science from a fixed belief is not that it is certain, it is that it accepts in advance what could bring it down. Its strength lies in its very revisability.

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Put to the test

Objection

Problem