وأما المقتضى: فهو زيادة على النص لا يتحقق معنى النص إلا به
The required implication is an unstated addition without which the text’s meaning cannot properly stand.
The first three modes draw rules from the expression and what its language communicates. Iqtiḍāʾ differs: an unstated element must be assumed for the expression to function intelligibly or lawfully in its context.
The required addition is not a free new command imposed on the text; it supplies what is indispensable for the statement’s validity or legal operation. A mere omitted phrase recoverable from the sentence and an indispensable legal presupposition need not have identical consequences.
This distinction appears in divorce, emancipation, and contractual transactions, where an expressed act requires an underlying legal condition or premise.