External consistency is defined as the requirement that evidence must not be:

External consistency is a critical principle in evaluating evidence within the context of arguments and debates. It specifically requires that the evidence presented should align with the majority of the available evidence and not contradict it in a significant or sharp manner. When evidence is in stark opposition to what is widely supported or accepted, it raises questions about its credibility and reliability. Such contradictions can undermine an argument's persuasive power and can lead to confusion or skepticism among the audience.

In contrast, other elements such as being outdated, overly complex, or self-referential may affect the usability or accessibility of the evidence, but they do not directly address the fundamental concern of how it interacts with existing evidence from outside sources. External consistency focuses primarily on the harmony and coherence of the evidence with the broader body of knowledge or consensus, making it essential for creating persuasive and effective arguments.