Wikipedia:Verifiability requires truth

For many years, Wikipedia’s Verifiability policy contained a blunt, catchy, and often-misunderstood slogan: "The threshold for inclusion in Wikipedia is verifiability, not truth." This phrase is meant to stop editors adding unsourced "facts" they "know" to be true. However, it is often cited (incorrectly) to keep incorrect information on Wikipedia, arguing that if a citation exists, the factual accuracy of the content is irrelevant.

This is a mistake. Verifiability is not an alternative to truth; it is a higher standard than truth. To be verifiable, material must be true. Verifiability requires truth.

Hierarchy of inclusion

"Verifiability, not truth" describes where Wikipedia falls on a hierarchy of inclusion standards. Many communities do not require information be verifiable (in practice, cited to reliable sources); instead, they allow users to add any information they know, even if it cannot be verified by a third party. These communities have a threshold of truth.

Wikipedia has a higher standard for itself. Our threshold is verifiability: To be included, a fact must be provably true. "Verifiability, not truth" is a warning that unlike fan wikis, WikiHow, or Know Your Meme, we won't accept your contributions unless we can verify them for ourselves. In other words, being right is not enough: you must also be able to prove you are right.

You cannot verify a lie

"Verify" has a standard meaning in English: to verify a fact is to make sure it is true. You cannot "make sure" that something false is true. If a generally-reliable source publishes a false statement, and you cite it, you have not "verified" that fact; what you have verified is that the source you cited is (at least sometimes) unreliable.

In 1920, The New York Times published an infamous piece claiming rockets could not function in a vacuum. Citing that article today does not verify this claim; it only verifies that a 1920 New York Times article is not a reliable source for rocket science.

Generally reliable sources are not magic totems that shield your claim from scrutiny; a reliable source is defined as one likely to be accurate. If a source is demonstrably wrong—as determined by WP:consensus, common sense, and better sources—it ceases to be a "reliable source" for that claim.

If you manage to "verify" a falsehood, this does not mean you have actually proven a falsehood: it means your verification procedure is flawed, and therefore cannot be relied upon.

Or an opinion

In the same way that it is impossible to verify falsehoods, it is impossible to "verify" an opinion. Even if dozens of New York Times articles write that "Cats is an awful movie", you cannot verify "Cats is a bad movie"; you can only show these writers hold this opinion. Opinions are subject to verification of existence, not verification of truth.

Do a sanity check

If you find yourself arguing we should include something you know is wrong because of your interpretation of the rules, you should pause and reflect. If the rule you followed brought you to this, of what use is the rule? Wikipedia is an encyclopedia, not a collection of attributed errors. Our goal is to provide accurate information, and any rule that keeps us from doing that should be ignored.