verifiable — to prove the truth of, as by evidence or testimony; confirm; substantiate: Events verified his prediction.
ascertainable — to find out definitely; learn with certainty or assurance; determine: to ascertain the facts.
axiomatic — If something is axiomatic, it seems to be obviously true.
certain — If you are certain about something, you firmly believe it is true and have no doubt about it. If you are not certain about something, you do not have definite knowledge about it.
deducible — to derive as a conclusion from something known or assumed; infer: From the evidence the detective deduced that the gardener had done it.
incontrovertible — not controvertible; not open to question or dispute; indisputable: absolute and incontrovertible truth.
indubitable — that cannot be doubted; patently evident or certain; unquestionable.
inferable — to derive by reasoning; conclude or judge from premises or evidence: They inferred his displeasure from his cool tone of voice.
palpable — readily or plainly seen, heard, perceived, etc.; obvious; evident: a palpable lie; palpable absurdity.
positive — admitting of no question: positive proof.
self-evident — evident in itself without proof or demonstration; axiomatic.