Passage Summary: If you define a culture as the sum of all its traditions, then every tradition is essential. If one tradition disappears, that specific 'sum' no longer exists, meaning the culture has been destroyed.

Conclusion: If a culture is defined as the totality of its customs, then those customs necessarily function to preserve that culture.

Reasoning: Under this specific definition, the loss of even one custom would mean the 'totality' no longer exists, which constitutes the destruction of that culture.

Analysis: The statement in question is the final clause: 'the abandonment of any custom... would... constitute that culture's destruction.' This functions as an explanation or a sub-premise that shows why the conclusion follows from the specific definition provided. It is the logical bridge that explains the 'trivial sense' mentioned earlier. When identifying roles, notice how this part of the sentence provides the 'how' for the conditional claim made in the previous clause.