I. The argument:
The canon is often regarded as the weak link in the Protestant case. External attestation rates at most a probably conclusion. So the Catholic apologetic apologist will say a Protestant has no right to invoke Scriptural authority since he has no authority for his canon of Scripture. In nature of the case, the Bible can’t refer to itself as a completed totality until it’s complete, and once it’s complete it can’t refer back to itself since any such reference would have to be after the fact. So we can only draw the boundaries of the canon from a vantagepoint outside the canon. That being so, our knowledge of the canon depends on the testimony of the Church. But absent a magisterium, this means that Protestants are leaning on a fallible process to yield a reliable result. Or so goes the argument. By way of reply:
II. External attestation.
i) This objection assumes that the only form of attestation is external attestation. Even if that were so, when Trent defines the scope of the canon, it appeals to the testimony of the church fathers. But in that event, the Roman church is reliant on the same basic sources as are the Protestant churches.
ii) If the case for the canon depends on historical evidence, so does the case for Catholicism. How does a Catholic apologist set out to prove the primacy of Rome or apostolic succession without some recourse to historical evidence? Tradition is but another name for history.
iii) Even if the case for the canon were entirely dependent on external attestation, that does not, of itself, introduce an element of uncertainty into the process. Once again, the Church of Rome has a low doctrine of Scripture because she has a low doctrine of providence. But there's nothing haphazard about ordinary providence. In Gen 24, for instance, the reader is expected to discern that God's hidden hand guided Abraham's servant to find the right wife for Isaac.
iv) Access to God's word is not merely a matter of general providence, but special providence, for revelation and redemption are correlative (cf. (e.g. Ps 147:19-20; Jn 4:22; Rom 3:2; 9:4; 10:9-16; Eph 2:12; 4:17-18). A probable providential inference has the practical force of strict inference. A full house may not be a royal flush, but it trumps three of a kind every time. If you knew that God had stacked the deck in such a way that the opposing player never got better than a straight, while dealing you a full house, you’d bet all your chips on that hand just as if it were a royal flush in spades.
III. Internal attestation.
However, the case for the canon is not only or primarily limited to external attestation. There are also multiple lines of internal evidence. You just need to look at how the Bible is put together.
By way of objection, a modern-day Catholic might counter that this appeal rests on a naïve, precritical view of Scripture. We can no longer invoke the witness of Scripture, because higher criticism has overturned the traditional time, place, and authorship of many Biblical books. To this I'd say two things:
i) Even if this were an argument against a Protestant canon, it is hard to see how it also amounts to an argument for a Catholic canon. It is no alternative to a fallible canon of infallible books to offer an infallible canon of fallible books. So this objection looks like the theological equivalent of a homicide/suicide in which a killer first murders his victim, then shoots himself in the head.
If Scripture is inspired, then its self-referential claims are similarly inspired. But if we cannot credit the Bible when it vouches for the circumstances of its own composition, then we cannot trust it in any other matters of consequence. So this objection either proves too much or nothing at all.
ii) This objection assumes that the findings of higher criticism are compelling. But conservatives scholars have written many books and articles in which they offer a point-by-point rebuttal of such sceptical theories.
My appeal to internal attestation will build on that foundation. The relevant literature, in a vast and varied series articles, monographs, commentaries, and Bible introductions, is in the public domain. I need not reinvent the wheel at this juncture.
Much of the internal attestation takes the form of cross-attestation. The density of allusion is so rich that I can only skim the surface for purposes of illustration.
1. OT Intratestamental attestation:
The Pentateuch constitutes a bloc of Scripture that is the cornerstone of what follows. And here are internal continuities as well. The Toledoth -formula (i.e., . "these are the generations of..." (Gen 2:4; 5:1; 6:9; 10:1; 11:10,27; 25:12,19; 36:1,9; 37:2]) serves as a structuring device. Joseph’s farewell address (esp. 50:24) supplies the anticipatory rationale for the Exodus (cf. 3:6ff.), while Exod 1:1-5 is a résumé of Gen 46:8-27 (cf. 35:22-26). Exod 1:1 opens with "and," connecting it with the preceding narrative. The latter chapters of Exodus had dealt with the material arrangements of the Tabernacle while Lev 1-17 deals with its staffing and activities. Lev 18-27 is preoccupied with laws that anticipate the conditions of the Conquest and settlement. Numbers takes up the narrative thread where Exodus left off. Deuteronomy is a document of covenant renewal. Chaps 1-3 succinctly recapitulate the prior narrative of Israel’s wilderness wandering. Chap 18:18ff. makes provision for a prophetic order. Chap 28:15ff. makes provision for Israel’s apostasy. Chap 31 hands off the reins of authority to Joshua. Josh 1:1 takes up from where Deut 34 (the obituary of Moses) leaves off. The ending of Joshua is taken up in Judges 1:1; 2:6-9. Ruth is situated in the period of the Judges (1:1) and sets the stage for the Davidic kingship. 1 Kgs 1-2 continues the transition of power from 2 Sam 9-20. Chronicles reviews the history of Samuel-Kings from a post-Exilic perspective, while its genealogies reach back to the very beginning of canonical history (1Chron 1:1f.). 2 Chron 36:22-23 is taken up in Ezra 1:1-4. Ezra and Nehemiah are synoptic. Esther updates the mortal enmity between the Israelites as the Amalekites— represented by Haman (3:1; cf. 1 Sam 15; Exod 17:16). The Pentateuch is also held together by various unifying devices such as narrative/poetry/epilogue sequencing and narrative typology.
The Law supplies the supporting material for the covenant lawsuit (Isaiah-Malachi). Likewise, the historical books provide background information on the social conditions under which the prophets labored (cf. 2 Kgs 19-20; 2 Chron 22-24; 35:25; 36:12,21-22; Ezra 5:1; 6:14).
It would be rather artificial to speak in terms of the canonization of the Psalter. The psalms of David and other inspired contributions (2 Sam 23: 1-2; 1 Chron 25:1,5) were not private compositions that had to win a wider recognition over time. Their composition was an indigenous and official expression of Israel’s devotional life from the get-go. Again, Solomon’s inspired wisdom and royal standing would have ensured immediate reception for his writings (1 Kgs 4:29-34). It is anachronistic to retroject rabbinical debates back into the formative period of the canon. There was, likewise, no process of canonization for the law of Moses (Exod 25:16,21; 40:20; Deut 10:2,5; 17:18; 31:9,24-26).
The intertextuality of the OT can be documented in detail, ranging from broad redemptive-historical surveys (e.g. 1 Sam 12:6-12; 2 Kgs 17; Neh 9; Ps 78; 105-106; 135-136) to specific allusions and applications, e.g. Josh 24:32 (Gen 33:19; 50:25); Judg 11:15-27 (Num 20-21); 1 Kg 2:27 (1 Sam 2:31-33); 1 Kg 16:34 (Josh 6:26); 2 Kg 18:4 (Num 21:4-9); 1 Chron 5:1 (Gen 35:22; 49:4); Ps 2; 89:20ff. (2 Sam 7:14); Ps 8 (Gen 1); Ps 83:9-12 (Judg 4-8); Ps 104; 148 (cf. Gen 1); Ps 114 (cf. Exod 14-15; Josh 3:13-17); Ps 132 (2 Sam 6-7); Eccl 3:20; 7:29; 12:7 (Gen 2-3). Isa 54:9 (Gen 9:11); Jer 26:18 (Mic 3:12); Ezk 14:14,20; 28:3,13ff. (Gen 1-3; 6:9ff; Job 1:1; Dan 6); Ezk 37:1-12 (Gen 1-2; Ps 46:4); Hos 12:3-4,12-13 (Gen 25:26; 27:41-29:30; 32:22-23); Micah 6:4; 7:20 (Gen-Exod); Zech 8:9 (Haggai).
We also have cases of nested intertextuality in which C adapts B, which, in turn, adapts A. For example, 2 Chr 6:41-42 is tertiary to Ps 132:6-10, which is secondary to 2 Sam 6:12-29. This is a higher-order form of cross-attestation.
2. Intertestamental attestation:
Let us now move to some examples of intertestamental attestation. The case for the OT canon is further simplified by the fact that the OT is practically canonized by the NT. This includes collective designations, viz., "the law and the prophets," "the scriptures," "the Psalms" (=Hagiagrapha?), "the oracles of God"; cita-tion formulas, viz., "God says"; quoting an author by name (e.g. Moses, David, Isaiah, Jeremiah, Daniel, Hosea, Joel, Jonah), sweeping historical references that span the canon—"from Abel to Zechariah" (=Genesis to Chronicles?)—as well as a pervasive subtextual fabric of allusion to the OT.
On the last point, it may be objected that bare allusion does not amount to canonical stature. Taken by itself, that is true enough. But when an allusion supports the express argument or narrative design, it does implicate the normative status of the primary source. The fact, moreover, that an author feels secure in merely alluding to the primary source generally supposes an unspoken recognition of and deference to the authority of that source on the part of his audience. Indeed, it trades on a traditional preunderstanding of the source in application to the question at hand.
If the NT canonizes the OT, there’s a sense in which the OT canonizes the NT OT inasmuch as the OT and NT form a unit: the OT represents promise; the NT, fulfillment. Thus, they are two halves of a whole. Judaism alone is a half-finished bridge.
Space does not permit a survey of all the NT citations and allusions to the OT. I just mention this because it constitutes one major line of evidence. As I said above, independent lines of evidence can converge on the same destination.