Theopedia

Epistemology

“The fear of the LORD is the beginning of knowledge; fools despise wisdom and instruction.”

— Proverbs 1:7 (ESV)

Definition

Epistemology is the branch of philosophy that asks what knowledge is, how it is obtained, and what separates a justified belief from mere opinion. Christian theology asks a version of the same question about knowledge of God specifically: what grounds a person’s knowledge of divine things, and how certain can that knowledge be? Reformed scholastic theology developed its own vocabulary for this, the doctrine of the principia (“foundations”) of theology, distinguishing what Scripture, the created order, and the Holy Spirit’s inward witness each contribute to a believer’s knowledge of God (Rom. 1:19-20; 1 Cor. 2:14; 2 Tim. 3:16-17).

Confessional Witness

The 1689 Second London Baptist Confession opens by addressing exactly this question: what supplies the rule by which anyone can have saving knowledge of God.

“The Holy Scripture is the only sufficient, certain, and infallible rule of all saving knowledge, faith, and obedience; although the light of nature, and the works of creation and providence do so far manifest the goodness, wisdom, and power of God, as to leave men inexcusable; yet are they not sufficient to give that knowledge of God and his will which is necessary unto salvation.”1

Two claims stand together here. General revelation, “the light of nature, and the works of creation and providence,” is real: it “manifests” God’s goodness, wisdom, and power well enough to leave everyone “inexcusable” for not honoring him. But it is not “sufficient to give that knowledge of God and his will which is necessary unto salvation.” Saving knowledge requires Scripture specifically.

The confession also addresses how anyone becomes certain that Scripture itself carries divine authority. Its own “heavenliness of the matter” and internal consistency count as arguments, but the confession locates the real ground of that certainty elsewhere: “our full persuasion and assurance of the infallible truth, and divine authority” of Scripture “is from the inward work of the Holy Spirit bearing witness by and with the Word in our hearts.”2 That same Spirit’s “inward illumination” is “necessary for the saving understanding of such things as are revealed in the Word”3. Scripture’s truth is objectively given, but grasping it savingly is not left to unaided reason. What is necessary for salvation, the confession adds, is nonetheless plain enough that “not only the learned, but the unlearned, in a due use of ordinary means, may attain to a sufficient understanding of them.”4 Later Reformed theologians gave this structure a technical vocabulary, distinguishing Scripture as the principium cognoscendi externum (“external cognitive foundation”) of theology from the Spirit’s own testimony as its principium cognoscendi internum (“internal principle of knowing”).5

Biblical Basis

Scripture claims to be the source of the saving knowledge the confession describes. “The heavens declare the glory of God, and the sky above proclaims his handiwork” (Ps. 19:1), a revelation Paul extends to all people: “what can be known about God is plain to them, because God has shown it to them. For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse” (Rom. 1:19-20). Even those without special revelation have some moral knowledge, since “the work of the law is written on their hearts, their conscience also bearing witness” (Rom. 2:15).

That general knowledge, Paul says elsewhere, does not by itself produce saving wisdom: “the natural person does not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned” (1 Cor. 2:14). The world’s own wisdom, in fact, fails to arrive at the knowledge that matters most: “since, in the wisdom of God, the world did not know God through wisdom, it pleased God through the folly of what we preach to save those who believe” (1 Cor. 1:21). Wisdom’s starting point is not autonomous reasoning but reverence: “the fear of the LORD is the beginning of knowledge” (Prov. 1:7). Special revelation supplies what general revelation cannot: “All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work” (2 Tim. 3:16-17), and its saving effect on the mind is itself traced to God’s own action: “Sanctify them in the truth; your word is truth” (John 17:17).

Historical Development

Medieval natural theology and the Reformed reception

Long before the Reformation, theologians debated how far unaided reason could reach toward the knowledge of God. Thomas Aquinas and Duns Scotus both held that natural knowledge of God, reasoning from the created order to its Creator, is real but limited in two ways. It is indirect: it works “along a path of inferring from natural things certain truths about God the Creator” rather than perceiving God himself directly. And it is common rather than proper to God: it can reach “some understanding of things that would pertain to God alone… but… does not fully identify who this God is in all his distinguishing marks or economic acts.”6 The Reformed orthodox inherited this qualified affirmation rather than rejecting it outright. Reasoning about God from creation, on their account, is “best undertaken within the sphere of Christian faith seeking understanding,” exercising a natural capacity that sin has weakened but “not altogether destroyed.”6

Calvin’s sensus divinitatis

John Calvin gave this natural capacity its most influential Reformed statement, naming it a sensus divinitatis, a “sense of divinity,” and a semen religionis, a “seed of religion.”7 “God himself implanted in all humans an understanding of his divine majesty, persistently renewing its memory and constantly instilling fresh drops,” Calvin wrote, and “this seed of religion can never be eradicated.”7 He paired that inward capacity with an outward one: God’s works in creation mean “people cannot open their eyes without being compelled to see him.”7 Where the Lutheran confessions were “very negative on all natural theology,” the Reformed confessions and theologians “consistently affirmed it”7, while still insisting, with the confession’s own language above, that this natural knowledge falls short of saving knowledge.

Reformed scholasticism: Scripture as the theological principium

Seventeenth-century Reformed scholastics gave the doctrine its sharpest technical statement. Francis Turretin held that reason “is presupposed by faith, and when properly subjugated, reason is seen as an indispensable tool,” but reason itself supplies no theological content of its own: “Reason is not a theological principium, but reason is a philosophical and metaphysical one.”8 Philosophy, on this account, studies only “the knowledge of things human and divine… as far as they can be known by the light of nature,” a lower science standing beneath theology, whose object “can only be apprehended through revelation.”8 Petrus van Mastricht drew a similar line between the “book of nature,” general revelation available to reason, and the “book of Scripture,” and warned against treating what God has said as binding only when it agrees with human reason.9

Herman Bavinck later systematized this same structure under the Latin term principia (“foundations”): God himself is theology’s principium essendi, its essential foundation; Scripture is the principium cognoscendi externum, the external foundation of theological knowledge; and the Holy Spirit is the principium cognoscendi internum, the internal principle by which that knowledge becomes a believer’s own.5 For this whole tradition, reason is not itself a source of theological knowledge alongside Scripture, but the God-given faculty by which revealed knowledge is received, tested, and organized: what Bavinck called “not a sacrifice of the intellect but mental health (sanitas mentis).”10

Barth and the twentieth-century natural theology debate

“In the wake of [Karl] Barth’s massive influence, the rejection of natural theology became a commonplace in twentieth-century theology,” part of a broader “post-Kantian skepticism about the power of reason to connect us with mind-independent reality.”11 That represented a break with the church’s own historic confidence, shared across the Reformed scholastic and Thomist traditions alike, that God’s existence can be demonstrated and that reason confirms what special revelation teaches (Rom. 1:20).11

Opposing Views

Two rival accounts locate the foundation of knowledge in the human subject rather than in revelation. Rationalism, in the line of Descartes, Spinoza, and Leibniz, treats reason alone as capable of ordering reality without dependence on revealed truth.5 Idealism, developed by Kant, Fichte, and Schelling, goes further, holding that the mind has access only to its own representations rather than to things themselves. Carried through consistently, that move “turns the faculty by which we order and analyze our perceptions into the very source of knowledge itself, as it were making the eye into the source of light,” so that “that which is not my thought is inconceivable, unknowable to me; it does not exist for me.”5 Reformed theology treats both options as versions of the same underlying claim, that the human mind can be its own principium, and opposes them with “the natural realism of our ordinary experience”: knowledge that begins outside the self, in a world (and a God) genuinely other than the knower.5

Objections and Responses

Doesn’t grounding all knowledge in Scripture’s own authority make Christian belief circular, assuming the very thing it needs to prove? Every account of knowledge, not only a Christian one, has to start somewhere that is not itself derived from a prior proof; the debate over rationalism and idealism above shows the same difficulty recurs for reason left to itself. The confession does not claim that Scripture’s authority is established by an argument from more basic premises; it locates the ground of certainty in the Spirit’s own testimony “bearing witness by and with the Word in our hearts,”2 a different kind of warrant than a syllogism supplies, not the absence of one.

If natural revelation gives real knowledge of God, doesn’t that compromise Scripture’s sufficiency by supplying a second, independent source of true religion? The tradition treats natural theology as a real but narrow capacity, not a rival channel of saving truth. What it yields is “common” rather than “proper” knowledge of God,6 sufficient to leave a person “without excuse” (Rom. 1:20) but never sufficient, on the confession’s own terms, “to give that knowledge of God and his will which is necessary unto salvation.”1 Voetius’s own definition of this natural capacity, “implanted theology,” describes only “a capacity or power or aptitude belonging to the rational faculties,” not a body of saving doctrine competing with Scripture.7

Related Doctrines

Further Reading

References

  1. The Second London Baptist Confession of Faith (1689), chap. 1, “Of the Holy Scriptures,” para. 1. ↩ ↩2

  2. The Second London Baptist Confession of Faith (1689), chap. 1, “Of the Holy Scriptures,” para. 5. ↩ ↩2

  3. The Second London Baptist Confession of Faith (1689), chap. 1, “Of the Holy Scriptures,” para. 6. ↩

  4. The Second London Baptist Confession of Faith (1689), chap. 1, “Of the Holy Scriptures,” para. 7. ↩

  5. Herman Bavinck, Reformed Dogmatics: Abridged in One Volume, ed. John Bolt (Grand Rapids: Baker Academic, 2011), chap. 3, “Foundations of Dogmatic Theology.” ↩ ↩2 ↩3 ↩4 ↩5

  6. Steven J. Duby, God in Himself: Scripture, Metaphysics, and the Task of Christian Theology (Downers Grove, IL: IVP Academic, 2019), chap. 2, “Preparation for the School of Grace,” 58-130. ↩ ↩2 ↩3

  7. Bavinck, chap. 7, “Knowing God.” ↩ ↩2 ↩3 ↩4 ↩5

  8. Alex Charles Tibbott, “Turretin and Theological Method,” in “De Impassibilitate Et Satisfactione: An Examination of the Methodological Implications of Trinitarian Classical Theism for the Doctrine of the Atonement” (PhD diss., The Southern Baptist Theological Seminary, 2024), 60-93. ↩ ↩2

  9. Petrus van Mastricht, Theoretical-Practical Theology, vol. 1, Prolegomena, trans. Todd M. Rester, ed. Joel R. Beeke (Grand Rapids: Reformation Heritage Books, 2018), chap. 1, “The Nature of Theology,” 167-219. ↩

  10. Bavinck, chap. 6, “Faith.” ↩

  11. Craig A. Carter, Contemplating God with the Great Tradition: Recovering Trinitarian Classical Theism (Grand Rapids: Baker Academic, 2021), chap. 2, “What Is Trinitarian Classical Theism?” ↩ ↩2