Reading Between the Lines: How to Evaluate Sources
Most of what you know, you know from sources. Evaluating those sources is the underrated skill that determines whether your beliefs track reality.
Almost everything you believe about the world, you believe because of a source. Direct experience accounts for a small fraction of what we know. The rest is mediated — through books, articles, conversations, expert testimony, institutional reports. Source evaluation is therefore not an optional add-on to critical thinking. It is the bulk of the work.
What to ask about a source
When you encounter a claim, several questions are worth asking before accepting it.
Who is the source, and what are they in a position to know? A doctor reporting on a treatment has different knowledge than a patient reporting on the same treatment. Both can be valuable; neither is interchangeable. Match the type of knowledge to the question being asked.
What incentives does the source have? Sources are not disinterested. They want certain things to be believed, for reasons that may or may not align with the truth. A pharmaceutical company’s study of its own drug is not invalid by virtue of the conflict, but the conflict is relevant information.
What evidence does the source rely on? A claim with citations and data behind it is in a different category than a claim made without support. Both might be true, but the supported claim is easier to evaluate.
What do other sources say? A claim that is contradicted by most independent sources deserves more skepticism than one that is corroborated. Convergence across sources is meaningful information.
Common errors
Source evaluation goes wrong in predictable ways.
The first common error is trusting sources by virtue of their format. A glossy production with confident presenters and good graphics can feel credible regardless of the underlying claims. Production values are not evidence of accuracy.
The second is trusting sources that confirm our existing beliefs and discounting sources that don’t. This is confirmation bias applied to source selection. The most reliable sources are often the ones we’re most reluctant to read.
The third is treating “independent thinking” as “ignoring all sources.” Some critical-thinking advocates lean too far in the direction of trusting no one. The correct position is to trust selectively, not to trust no one. We need sources; the question is which ones and how much.
Building a source diet
A useful exercise is to inventory the sources you actually consume. What news outlets? What books? What podcasts? What experts? Then ask: how diverse is this list, in terms of perspective, in terms of methodology, in terms of incentives?
If the list is narrow, your view of the world is narrow in predictable ways. Adding sources that disagree with your current views, that come from different traditions, that have different financial backing — this is one of the most efficient ways to improve your overall picture of reality.
The investment is not glamorous. Reading sources you disagree with is unpleasant; consuming dense methodological discussion is boring; cross-checking claims is tedious. But the long-run difference between someone who does this work and someone who doesn’t is enormous. The skilled consumer of sources can move closer to truth even in domains where they are not personally an expert. The unskilled consumer is at the mercy of whichever source happens to reach them.
