We all know that our senses and our mental faculties, no matter how acute, are too feeble and fickle to be ultimately trustworthy as sources of truth. This does not mean that they are not instruments of truth, but they are not equipped to generate what is needed when the source or ground of truth and authority is in question. Not only so, but since the entrance of sin in the world, we have a sinful bent against ultimate truth and authority, unless God so changes our hearts as to rejoice in such things.

So what can provide what we need? Is there any way to be sure that God’s Word is just that—his Word? These questions seem to dominate our times, when all authority and certainty are being questioned. They are important questions; they are questions that get at the root of our relationship to God. In order to address these typical and natural questions, we need to delve more deeply into what we mean when we speak of the “ground” of truth and authority.

The question of the ground or foundation of the world and everything in it is not a new one.² As far back (at least) as the philosopher Aristotle, the question of the ground of everything else was discussed and debated. In such debates, two things were clear: (1) whatever ground we determine to be in place, it must be such that it has nothing behind or beyond it. To posit something behind or beyond this ground would make that thing the ground; (2) it is impossible to continue positing a ground, of a ground, of a ground, of a ground, etc. For a ground to be a ground it has to be that upon which everything else rests. Aristotle argued that all grounds or first principles or beginning points are the “first point from which a thing either is or comes to be or is known. . . .” In other words, “grounds,” according to Aristotle, provide the bedrock foundation for everything that is or is known. This concept of a beginning point, what some have called an Archimedean point, is a necessary and crucial aspect of everything that we think, indeed, of everything that is.³ Aristotle understood this, philosophy has continued to articulate this idea, and Christian theology has seen it as basic to its own discipline.

We can think of grounds, by analogy, the way we think of the physical ground underneath us. What is it that supports the room that I am now in? It is the boards in the floor. But what supports those boards? The beams underneath. What supports those beams? It is the ground underneath and around those beams. What supports the ground? Well, the ground supports itself. It is the support without which nothing else could be a support. As is the case physically, so it is with questions of ultimate authority, truth, etc. There is a “place” beyond which we cannot go and without which we cannot move. That place is the ground or “grounds.”

The theology that was resurrected during the time of the Reformation (sixteenth century) and beyond argued that all disciplines, especially theology, require grounds, and that such grounds partake of at least the following characteristics: (1) they are necessarily and unchangeably true, and (2) they must be known per se, that is, in themselves, as both immediate and indemonstrable. “Immediate” here means that the status of a ground is not taken from something external to it, but is inherent in the thing itself. It does not mean, strictly speaking, that nothing mediates the truth therein, but rather that nothing external to the ground mediates that truth. Similarly, “indemonstrable” here means that the fact of a ground is not proven by way of argument using principles external to that ground, but is such that it provides the ground upon which any other fact or demonstration depends.

This concern for grounds, historically, had its focus in two primary disciplines: philosophy and theology. In philosophy, the concern was expressed in the thought and philosophy of René Descartes. For all that separated Descartes’ philosophy from the Protestant theology of his day—and there was much that did—the concern for grounds was common to both. Descartes thought that his grounds were “clear and distinct ideas” concerning first the self and then God. These two, in that order, were supposed to provide the foundation for everything else that could be known. But Descartes’ rationalism (since he wanted to begin with innate ideas) only led to skepticism.

Christian theologians during this time argued, against rationalism, that grounds could never be located in the human self. To do so would lead to the kind of skepticism that followed in the wake of Descartes’ philosophy. What, then, is the ground of theology? What is it that can provide the foundation, the source and beginning point of all truth and authority? To ask the question is almost to answer it.

In the Westminster Confession of Faith (perhaps the ablest expression of Protestant doctrine in the entire history of the church), the authors set out, for the first time in church history, a Protestant doctrine of Scripture. In chapter 1 of the Confession, section 4, the authors wrote:

The authority of the Holy Scripture, for which it ought to be believed, and obeyed, dependeth not upon the testimony of any man, or Church; but wholly upon God (who is truth itself) the author thereof: and therefore it is to be received, because it is the Word of God.

Notice that the subject of this section is the authority of Scripture. They are answering the question of grounds for such authority. On what grounds does this authority depend?

It does not depend on any man or church. This was stated, negatively, to make clear that this was a Protestant and not a Roman Catholic doctrine of Scripture. But notice here that the authors say, in effect, that the authority of Holy Scripture depends on its author. It is the author of Holy Scripture who makes Scripture what it is.

The fact of the matter is, if we fail to see Holy Scripture as authored by God, and therefore as the ground of its own authority, we will fail to understand what Scripture actually is.

And, as the Confession makes clear, if we want to know why we should accept Holy Scripture as the Word of God, it is “because it is the Word of God.” That is, not simply because it says that it is; many books make such claims. Rather, we accept it because God is its author and God says that it is. To appeal to something behind, above, or beyond this is to think of Scripture (and God) as something other than the ground of truth and authority.

Isn’t this what Jesus himself was saying to the devil in the wilderness? Jesus had the power to show Satan who he was. But Jesus also knew that whatever he did would detract from Satan’s central objection. His objection was not that he hadn’t seen all he needed to see. Jesus knew that Satan’s objection was focused on the fact that he did not believe what God had said.

Jesus illustrated this same principle in the parable of the rich man and Lazarus (Luke 16:19–31). The rich man in Hades asks that there be demonstrations of power and miracles displayed to his five brothers so that they might not suffer the same torment. What is the response to this request? “If they do not hear Moses and the Prophets, neither will they be convinced if someone should rise from the dead” (Luke 16:31).