Final answer:
The principle that the evidence is unrelated to the conclusion justifies the reasoning that the argument is illogical, highlighting the importance of relevant premises and coherent inferences in constructing a valid argument.
Step-by-step explanation:
Based on the information given, the principle that most helps to justify the reasoning above is that the evidence is unrelated to the conclusion. The premises being true alongside the conclusion does not inherently mean the argument is logical if the premises do not support the conclusion. An argument must contain a clear inference, moving logically from the premises to the supported conclusion. However, if the premise is irrelevant, then there's an absence of a coherent inference, and thus the argument fails to be convincing.
Another crucial aspect is the presence of concrete evidence which offers support to the claim; without it, readers cannot fully grasp the concept being argued. This leads to a lack of clarity and coherence within the argument. Consequently, for an argument to be effective, its premises must not only be related but also adequate to back the conclusion.