 The core of this definition is the notion of “resulting of necessity” (ex anankês sumbainein). This corresponds to a modern notion of logical consequence: \(X\) results of necessity from \(Y\) and \(Z\) if it would be impossible for \(X\) to be false when \(Y\) and \(Z\) are true. We could therefore take this to be a general definition of “valid argument”.