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No. 280 · Evidence · Fallacy

Non Sequitur

True facts can still be strung together into a conclusion that does not follow.

A non sequitur is an argument where the conclusion has no logical link to the evidence. Soviet authorities rejected genetics because it was labelled bourgeois, and an iced-tea company's stock soared just by adding blockchain to its name.

When an argument sounds convincing, trace each step and ask, so what? Look for the missing link between the facts and the claim. Sometimes the link is real but unstated, so ask for it before dismissing the argument.

In the Almanac

“Lysenko’s biology”, 1948 · “Long Blockchain”, 2017

Both stories in full, three ways to use it and where it misleads.

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Non Sequitur: When Logical Connections Go on Holiday

Questions

What is Non Sequitur?

A non sequitur is an argument where the conclusion has no logical link to the evidence. Soviet authorities rejected genetics because it was labelled bourgeois, and an iced-tea company's stock soared just by adding blockchain to its name.

How do you avoid Non Sequitur?

When an argument sounds convincing, trace each step and ask, so what? Look for the missing link between the facts and the claim. Sometimes the link is real but unstated, so ask for it before dismissing the argument.

When does Non Sequitur matter?

Non Sequitur is one of the 68 mental models for evidence, the situations where you ask: Is this really true? Within that, it belongs to “Spotting a bad argument”, alongside Ad Hominem, Appeal to Authority and Appeal to Emotion.

What is an example of Non Sequitur?

Two stories show it at work: Lysenko’s biology (1948) and Long Blockchain (2017). Both are told in full in The Mental Models Daily Almanac, which has two stories for each of its 365 models.

Which mental models are related to Non Sequitur?

Causal Fallacy, Halo Effect and Bandwagon Effect. Non Sequitur itself comes from fallacy.