That cannot be proved or verified by any test (adjective)
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Use "unprovable" in a sentence
"According to Dawkins, that makes science “one of the world’s great evils”, since scientists start with faith that certain unprovable assumptions are true; among others – the objective existence of the material universe, that is is governed by rational laws, the reliability of human reason, the reliability of observation."
"Don't give me this load about degineration if you are going to make assertions such as, the * "unprovable" aspects of an open agenda, and expect no reply."
"Postmodernism, a self-consciously "unprovable" theory, replaced formal structures with subjectivity."