Turretin poses the sixteenth question of the second topic this way:
Do the Scriptures so perfectly contain all things necessary to salvation that there is no need of unwritten (agraphois) traditions after it? We affirm against the papists.Francis Turretin, Institutes of Elenctic Theology, trans. George Musgrave Giger, ed. James T. Dennison, Jr., Vol. 1 (Phillipsburg: P&R Publishing, 1992), II.xvi, p. 134.
This section of Turretin deals with what he calls the "perfection" of Scripture, which is closely tied to the issue perspicuity. He addresses perspicuity in the seventeenth question, thus:
Are the Scriptures so perspicuous in things necessary to salvation that they can be understood by believers without the external help of oral (agraphou) tradition or ecclesiastical authority? We affirm against the papists.Francis Turretin, Institutes of Elenctic Theology, trans. George Musgrave Giger, ed. James T. Dennison, Jr., Vol. 1 (Phillipsburg: P&R Publishing, 1992), II.xvii, p. 134.
Notice the careful wording of both questions. Turretin is not saying that there is no place for other aids. For example, in the 6th point under the 17th question, Turretin states:
The question does not concern the perspicuity which does not exclude the means necessary for interpretation (i.e., the internal light of the Spirit, attention of mind, the voice and ministry of the church, sermons and commentaries, prayer and watchfulness). For we hold these means not only to be useful, but also necessary ordinarily. We only wish to proscribe the darkness which would prevent the people from reading the Scriptures as hurtful and perilous and compel them to have recourse to tradition when they might rest in the Scriptures alone.Francis Turretin, Institutes of Elenctic Theology, trans. George Musgrave Giger, ed. James T. Dennison, Jr., Vol. 1 (Phillipsburg: P&R Publishing, 1992), II.xvii.vi, p. 144.
In the course of his discussion, however, Turretin pointed out some Roman counter-positions:
In order to clear themselves of the charge of attributing insufficiency to the Scriptures in this way, some of them distinguish between explicit and an implicit sufficiency (as Stapleton and Serarius) or mediate and an immediate (as Perronius). And they confess that the Scripture is not indeed sufficient immediately and explicitly, but yet it can be called so mediately and implicitly because it refers to the church and to tradition what is not contained in itself.Francis Turretin, Institutes of Elenctic Theology, trans. George Musgrave Giger, ed. James T. Dennison, Jr., Vol. 1 (Phillipsburg: P&R Publishing, 1992), II.xvi.xi, p. 136.
In my view (though I do not claim to speak for Pastor King here), Turretin is here dealing with a kind of partim-partim sufficiency view. In other words, at least some of the Roman opponents of Turretin were saying that Scripture's sufficiency came through pointing readers to the church and tradition. That particular sense of sufficiency isn't quite the same as Yves Congar's material sufficiency, but it's also certainly not the Reformed view.
Turretin provided an excellent response to this partim-partim sufficiency view:
A false distinction is made by Perronius between mediate and immediate sufficiency, so that the Scriptures may be called sufficient not in the second but in the first sense because they refer us to the church to supply their defects. This would imply a true insufficiency in the Scriptures, for by appealing to the church as having that sufficiency, it would declare its own insufficiency. (2) Then the law might be called perfect for salvation because it refers us to Christ in whom is salvation. (3) The Scriptures do not refer us to the church that she may propose new doctrines, but explain and apply the truths already contained in them. Nor ought the reply to be made here that we hold mediate sufficiency when we maintain that the Scriptures (if not expressly, at least by consequence) contain all things necessary to salvation. When the Scriptures teach anything by consequence, they do not refer us to another for instruction, but give forth from themselves what was virtually latent. Nor can the simile adduced by Perronius of credential letters (literarum credentiae, which are called sufficient although they do not contain all the instructions given to the ambassador) apply here. The Scriptures are not only a credential letter, but also the edict of a king, containing so fully all the things to be believed and done that nothing can be added.Francis Turretin, Institutes of Elenctic Theology, trans. George Musgrave Giger, ed. James T. Dennison, Jr., Vol. 1 (Phillipsburg: P&R Publishing, 1992), II.xvi.xxvii-xxviii, pp. 140-141.
The perfection of Scripture asserted by us does not exclude either the ecclesiastical ministry (established by God for the setting forth and application of the word) or the internal power of the Holy Spirit necessary for conversion. It only excludes the necessity of another rule for external direction added to the Scriptures to make them perfect. A rule is not therefore imperfect because it requires the hand of the architect for its application.
Rome has not definitely answered the martial sufficiency vs. the partim-partim view, although seemingly virtually all the Tridentine fathers held to a partim-partim view and virtually all modern Roman apologists hold to a material sufficiency view.