Arbitrary
"Arbitrary" means a claim put forth in the absence of evidence of any sort, perceptual or conceptual; its basis is neither direct observation nor any kind of theoretical argument. [An arbitrary idea is] a sheer assertion with no attempt to validate it or connect it to reality.
If a man asserts such an idea, whether he does so by error or ignorance or corruption, his idea is thereby epistemologically invalidated. It has no relation to reality or to human cognition.
Remember that man's consciousness is not automatic, and not automatically correct. So if man is to be able to claim any proposition as true, or even as possible, he must follow definite epistemological rules, rules designed to guide his mental processes and keep his conclusions in correspondence to reality. In sum, if man is to achieve knowledge, he must adhere to objective validating methods -i.e., he must shun the arbitrary . . . .
Since an arbitrary statement has no connection to man's means of knowledge or his grasp of reality, cognitively speaking such a statement must be treated as though nothing has been said.
Let me elaborate this point. An arbitrary claim has no cognitive state whatever. According to Objectivism, such a claim is not to be regarded as true or as false. If it is arbitrary, it is entitled to no epistemological assessment at all; it is simply to be dismissed as though it hadn't come up . .. . The truth is established by reference to a body of evidence and within a context; the false is pronounced false because it contradicts the evidence. The arbitrary, however, has no relation to evidence, facts, or context.
It is the human equivalent of [noises produced by] a parrot . . . .
sounds without any tie to reality, without content or significance.
In a sense, therefore, the arbitrary is even worse than the false. The false at least has a relation (albeit a negative one) to reality; it has reached the field of human cognition, although it represents an error - but in that sense it is closer to reality than the brazenly arbitrary.
I want to note here parenthetically that the words expressing an arbitrary claim may perhaps be judged as true or false in some other cognitive context (if and when they are no longer put forth as arbitrary), but this is irrelevant to the present issue, because it changes the epistemological situation. For instance, if a savage utters "Two plus two equals four" as a memorized lesson which he doesn't understand or see any reason for, then in the context it is arbitrary and the savage did not utter truth or falsehood (it's just like the parrot example). In this sort of situation, the utterance is only sounds; in a cognitive context, when the speaker does know the meaning and the reasons, the same sounds may be used to utter a true proposition. It is inexact to describe this situation by saying, "The same idea is arbitrary in one case and true in another." The exact description would be: in the one case the verbiage does not express an idea at all, it is merely noise unconnected to reality; to the rational man, the words do express an idea: they are conceptual symbols denoting facts.
It is not your responsibility to refute someone's arbitrary assertion - to try to find or imagine arguments that will show that his assertion is false. It is a fundamental error on your part even to try to do this. The rational procedure in regard to an arbitrary assertion is to dismiss it out of hand, merely identifying it as arbitrary, and as such inadmissible and undiscussable.
~ Found at the Ayn Rand Lexicon - Arbitrary
~ Leonard Peikoff, The Philosophy of Objectivism lecture series, Lecture 6
