A field guide to the ways reasoning breaks
Broken structure
Also called Intensional fallacy, illicit substitution
Substituting identical things inside a statement about belief or knowledge, where it does not hold.
I know my colleague; I do not know the thief; so my colleague is not the thief.
Note that knowing about something is a fact about the knower, not about the thing.
Named for a stock example in analytic philosophy: I know who my friend is; I don't know who the masked man across the room is — so my friend is not the masked man. The argument fails because it treats 'known by me' as a property of the person, when it is a fact about me. It is an illicit use of Leibniz's law in an epistemic context.
The board approved Project Falcon; nobody admitted to approving the leaked plan; so the leaked plan is not Project Falcon — and it was, under a different codename.
Alice knows the sender of the encrypted email; she does not know who runs the anonymous account; so they can't be the same person.
The witness can describe the driver; he cannot describe the defendant; so the defendant was not the driver.
Users trust the official app; users do not trust the new SDK; so the SDK can't be part of the official app — both shipped in the same build.