Passage Summary: Just as you wouldn't trust a letter without a signature, you should be wary of unnamed sources in the news because they can lie without consequences.

Conclusion: It is reasonable to maintain a skeptical attitude toward anonymous sources used in news stories.

Reasoning: Anonymous sources, like the writers of unsigned letters, can provide false or biased information without being held accountable for it.

Analysis: The columnist uses an analogy to build their case, comparing news sources to unsigned letters. By identifying a shared characteristic—anonymity—the author argues that the skepticism we naturally feel toward one should apply to the other. When identifying the method of reasoning, focus on how the argument draws a parallel between two different scenarios to support a general principle of caution. It’s a structural comparison meant to highlight a specific risk: the lack of accountability.