invalidate it through refutation and counterargument.”

The reply is:

If the person framing the definition has provided no proof of its soundness, the listener cannot come to know what is defined through it, since the person framing it may be mistaken. For if the listener does not know from the speaker’s statement that the definition is sound, and that statement may be true or false, he cannot come to know what is defined through that statement.

It is astonishing that these people claim that these are rational methods yielding certainty. They make knowledge of the simple the foundation of knowledge of the composite, yet place their reliance here on a definition that is merely the unsupported statement of the person framing it. It is a report from a single individual concerning a rational matter, not a sensory one, and admits of correctness and error, truth and falsehood. Then they criticize those who, in matters known through transmission, rely on a single transmitter’s report accompanied by contextual evidence that gives certain knowledge to a listener acquainted with it. They claim that a single transmitter’s report does not impart knowledge. Yet even if such a report does not impart knowledge, this is precisely what their own account of definition amounts to: it is a report from a single individual, with no proof of its truth. Indeed, according to them, no proof of its truth can even be established.

Thus, the definition does not convey a conception of what is defined. If, however, the listener has conceived what is defined before hearing the definition, or conceives it while hearing it or afterwards, independently of the definition, and knows that this is its definition, he knows that the person framing it has defined it truthfully. In that case, the definition has not conveyed the conception. This is clear.

In summary, conceiving what is defined through a definition is impossible without knowing that the statement of the person framing it is true. The truth of his statement cannot be known merely from his assertion. Hence, what is defined cannot be known through the definition.

Third:

It may be said: If a definition conveyed a conception of what is defined, one could not attain