Argument from sign

This movie must have been directed by Christopher Nolan because it has a non-linear plot.

The subjects are the same and the predicates are different, so the argument form is alpha (a is X because a is Y): “This movie (a) must have been directed by Christopher Nolan (X) because it (a) has a non-linear plot (Y).”

Both the conclusion and the premise can be classified as statements of fact (F), so the argument substance is FF: “This movie must have been directed by Christopher Nolan (F) because it has a non-linear plot (F)”.

The keyword SIGN describes the relationship between predicates Y and X. The argument lever can thus be formulated as “Having a non-linear plot (Y) is a SIGN of having been directed by Christopher Nolan (X)”.

Source

This is an invented example.

Other examples

• She must adore Patricia because she is looking at her all the time.
• You probably eat too much fruit because you are frequently bloated (https://lilynicholsrdn.com/5-signs-youre-eating-too-much-fruit/).
• This mushroom is poisonous because it has white gills.
• All human beings by nature desire to know, because all human beings have a liking for their senses (from the opening paragraph of Aristotle’s Metaphysics: “All human beings by nature desire to know. A sign of this is our liking for the senses; for even apart from their usefulness we like them for themselves – especially the sense of sight, since we choose seeing above practically all the others, not only as an aid to action, but also when we have no intention of acting. The reason is that sight, more than any of the other senses, gives us knowledge of things and clarifies many differences among them” (Aristotle, Metaphysica 980a21-27 as translated by T. Irwin and G. Fine (1995), Aristotle – Selections, Indianapolis: Hackett)).

Notes