Final answer:
When an assumption introduces a term not in the evidence, it reveals a logical fallacy as it lacks support for the conclusion, highlighting an error in reasoning.
Step-by-step explanation:
When the conclusion of an argument introduces a term not mentioned in the evidence, and there is an assumption that attempts to bridge this gap, the assumption often uncovers a logical fallacy. This occurs because the assumption is not supported by evidence presented in the premises and therefore does not logically warrant the conclusion. It is essential for a strong argument that the evidence logically supports the conclusion. In circumstances where the premises are inadequate in providing support to the conclusion or when they are entirely irrelevant or disconnected, we often encounter situations where the assumption made requires further justification, which indicates the presence of a logical fallacy. A fallacy of this nature points towards an error in reasoning, where the argument fails to maintain a valid logical structure, such as the Fallacies of unwarranted assumption. Thus, the assumption in question does not lead to valid reasoning but rather reveals a fault in the inferential process of the argument.