In a few weeks I am going to participate in a live panel discussion entitled “Four Views on Christian Apologetics”. The panelists include Dr. James White (representing presuppositionalism), Dr. Richard Howe (representing classical apologetics), Dr. Randal Rauser (representing reformed epistemology) and myself (representing evidentialism). The event takes place on Friday July 17th at 9pm Eastern time and will be aired on the Explain Apologetics YouTube channel. You can tune in to the live-stream here.
In this article, I will lay out some of the reasons why I prefer the evidentialist system over its competitors. Of course, the topic is far too broad for me to do justice to it here and there will inevitably be much ground that I have left covered. I of course also understand that each of the broad camps has a variety of different nuancies and perspectives which I cannot begin to unpack in this short article. However, I hope that this article may serve as an introduction to the topic. I will also not dwell here on Alvin Plantinga’s reformed epistemology, which (lamentably, in my judgment) has risen to popularity among many contemporary apologists. Suffice it to say here that I am not an adherent of reformed epistemology, and I do not claim to have any sort of mystical inner-witness that provides veridical testimony to the truth of Christianity independent of the public evidence. Indeed, I don’t believe it is the normative experience for Christians to have a veridical experience of God that provides sufficient warrant for belief in Christianity. I know that I certainly don’t have any such experience to speak of, and I know plenty of Christians who would say the same thing. I of course don’t deny that in exceptional cases God could make His existence known to someone in a manner that warrants belief, but as I said I do not believe that is God’s normative modus operandi.
It is also not at all clear to me how one would reliably distinguish a mystical inner-witness of the Holy Spirit from the testimony of the Mormon who says that God has “shown” them that the book of Mormon is Scripture because they experienced the infamous burning in the bosom. I don’t believe anything in Scripture indicates that the Holy Spirit’s job is to provide any such mystical experience. The verse that is typically quoted to support this is Romans 8:16 which says “The Spirit himself bears witness with our spirit that we are children of God.” However, in context, this is talking about the fruit of the Spirit which is necessarily borne in the life of the believer, thereby confirming that we are indeed born again. It has nothing to do with a mystical confirmation that Christianity is true. Scripture consistently appeals to evidence to establish this, such as predictive prophecy (e.g. Deuteronomy 18:21-22; Isaiah 41:21-24) and the resurrection of Jesus (e.g. Acts 17:31). Furthermore, I think often-times Christians can confuse an implicit rational warrant for belief in Scripture (which is based on public evidence) with some sort of mystical inner-witness of the Holy Spirit. For example, one may have an inarticulate sense of the power of the whole case for Christianity without realizing that it is, in fact, a rational response to a cumulative case argument.
In what remains of this article, I turn my attention to laying out, as briefly as I can, why I am a staunch defender of evidentialism. In doing so, I will contrast it with the classical and presuppositionalist system, and explain why I prefer the evidentialist system over the alternatives. Technically, evidentialism as an apologetic system may be distinguished from evidentialism as an epistemology. William Kingdon Clifford famously defined epistemological evidentialism with the dictum that “it is wrong, everywhere, always, and for anyone, to believe anything upon insufficient evidence” . Alvin Plantinga criticizes this view, arguing that it is “self-referentially incoherent” since it “lays down a standard for justified belief that it doesn’t itself meet” . Ken Boa and Robert Bowman therefore formulate their own maxim for evidentialist apologetics: “it is wrong, everywhere, always, and for anyone, to tell someone else to believe something other than on the basis of evidence.” 
The problem Plantinga envisages, however, can be circumvented by instead adopting the dictum that “It is always a mistake to repose more confidence in a contingent proposition than is justified by the evidence one possesses.” I would argue that epistemology is an a priori discipline. That is to say, true epistemic claims are true by definition. Therefore, since this statement is not a contingent proposition, it does not fall within its own scope, and there is no self-reference problem. I have addressed other typical objections to evidentialism, including Biblical ones, in previous articles. These include the so-called noetic effects of sin (i.e. the supposed effects of sin on the intellect) as well as other objections. I also recently delivered a presentation on this subject at South African Theological Seminary, which you can find here.
One method by which many evidentialists measure the strength of evidence, which makes sense to me, is in terms of the ratio of two probabilities P(E|H) and P(E|~H) – i.e. the probability of the evidence (E) given that the hypothesis (H) is true, and the probability of E given that H is false. That ratio may be top heavy (in which case E favors H), bottom heavy (in which case E favors ~H), or neither. Bayes’ Theorem is a mathematical tool for modelling our evaluation of evidence to appropriately apportion the confidence in our conclusions to the strength of the evidence.
The equation given below represents the odds form of Bayes theorem, which is used in developing cumulative cases. Translated, it states that the posterior probability of your hypothesis (H) given the available evidence (E) is equal to the prior probability of the hypothesis being true (expressed as a ratio) multiplied by the ratio of the evidence given the hypothesis against the probability of the evidence given the annulment of that hypothesis.
Priors can be established on the basis of past information. For example, suppose we want to know the odds that a particular individual won last week’s Mega Millions jackpot in the United States. The prior probability would be set at 1 in 302.6 million. That is a low prior probability, but it could be overcome if the supposed winner were to start routinely investing in private jets, sports cars, and expensive vacations. Perhaps he could even show us his bank statement, or the documentary evidence of his winnings. Those different pieces of evidence would stack up to provide powerful confirmatory evidence sufficient to overcome a vanishingly small prior probability to yield a high posterior probability that the individual did indeed win the Mega Millions jackpot. In other situations, setting an objective prior is more difficult, and in such cases priors may be determined by a more subjective assessment.
Of the apologetic systems, the differences between evidentialism and classical apologetics are the most minor. The primary defining difference between the evidentialist approach and the classical apologetic approach is the view that historical miracles, such as the resurrection, can stand on their own as evidence for the existence of God. By contrast, a classical apologist would want to highlight the need, as a matter of principle, to begin with philosophical arguments for the existence of God before one can make the case for miracles, since miracles – being defined as special divine action – cannot even be considered possible unless God exists. Thus, so the argument goes, to use miracles as evidence for God would be to reason in a circle, since a miracle cannot occur unless there is a God to perform the miracle. It is certainly true that miracles are impossible if God does not exist, and in that case no amount of evidence would suffice to warrant belief in miracles (in the same way that no amount of evidence can ever be sufficient to establish the existence of a married bachelor). The classical apologist may not deny that arguments for the resurrection may have practical value in terms of persuasion, independent of a philosophical defense of theism. However, they would argue that to be consistent one must begin with a philosophical defense of theism (at least if theism is not already affirmed by one’s interlocuter) before one presents the case for the resurrection. To this, however, I would respond that, while it is true that miracles are impossible unless God exists, it does not follow that miracles are impossible unless there is an independent demonstration of God’s existence. Provided that there is no positive demonstration that God does not exist, the prior probability of God performing a miracle is non-zero. And any non-zero prior probability can in principle be overcome given sufficient evidence.
There are also ways by which one can raise the prior probability of the resurrection independent of the classical arguments for the existence of God. For example, William Lane Craig emphasizes the theo-historical context of the resurrection of Jesus as providing some reason to think that God plausibly would have had motivation to raise Jesus of Nazareth from the dead as God’s vindication of Jesus’ Messianic self-claims. I would flesh this out further by highlighting instances of what I call Messianic convergence in the gospels, which I have discussed in detail in my writing.
The other major contending apologetic system is presuppositionalism, pioneered by Cornelius Van Til  and his successor Greg Bahnsen  and championed in contemporary discourse by Scott Oliphant , which would maintain that one has to begin with the authority of Scripture before one can have a consistent basis on which to assume even the possibility of reason or knowledge, and that there can be no set of neutral assumptions from which to reason with a non-Christian. Cornelius Van Til states that ,
“This [apologetic method] implies a refusal to grant that any area or aspect of reality, any fact or any law of nature or of history, can be correctly interpreted except it be seen in the light of the main doctrines of Christianity.”
Van Til’s successor Greg Bahnsen, furthermore, claimed that “Christianity is reasonable in virtue of the impossibility of the contrary” .
However, I deem this system to compromise sound principles of reason and therefore it should be rejected. For example, it mistakes arguments for God’s ontological necessity with arguments for God’s epistemological necessity. To illustrate, oxygen is ontologically necessary for one to verbally communicate, but it is not necessary for one to know this in order to verbally communicate. No Christian thinker would deny that God is ontologically necessary to account for all that exists in the world. In presenting the transcendental argument for God’s existence, however, the presuppositionalist frequently lapses into presenting arguments for God’s ontological necessity, when what he ought to have done is present arguments for God’s epistemological necessity. This is common case of equivocation among advocates of presuppositionalism.
Furthermore, the laws of logic are true by necessity – that is, in every possible world. Thus, it is not obvious to me that the proposition of God is required to account for them (since they could not have been otherwise). Thus, it is not at all clear to me that invocation of God is necessary to account for the laws of logic, since it is impossible to conceive of a world in which logic did not exist. Moreover,even if the transcendental argument for the existence of God holds (which I am not convinced that it does), it at best only demonstrates the existence of God. It is not at all clear to me that it demonstrates that God has revealed Himself in the person of Jesus or communicated to us through the Bible. It is also never clearly addressed by presuppositionalists what exactly defines “Christianity.” For example, what doctrines need to be accepted before one can have an adequate account for the laws of logic? What Biblical books or doctrines, if they were to be removed from our canon or creeds respectively would throw us into absurdity? I have never seen those questions adequately addressed.
Another troubling issue is that, in responding to the charge of circularity (i.e. including the conclusion as a premise of the argument), presuppositionalists typically respond by highlighting that everyone must begin with first principles that are themselves unjustified (such as the laws of logic). Therefore, according to presuppositionalist, all reasoning is in some sense circular since everyone must begin from some ultimate starting point. For example, how does one justify the principles of deduction without using deduction to do so? The presuppositionalist thus draws a distinction between so-called vicious and virtuous circular reasoning. However, this is where presuppositionalists engage in another equivocation fallacy. That is, they equivocate presuppositions of first principles (such as mathematical truths and the laws of logic), which are true by definition, and presuppositions involving content (such as the statement that “Jesus rose from the dead”).
To understand this equivocation, consider the statement that “all bachelors are unmarried.” This is an analytic statement that is true by definition. One does not need to go out and investigate whether or not it is true that all bachelors are unmarried. It is true by virtue of what we mean by “bachelor” and what we mean by “unmarried.” Likewise, the laws of logic, i.e. the law of non-contradiction, the law of identity, and the law of the excluded middle are true by definition. It is true by definition that “a” cannot be “non-a” in the same sense at the same time. Likewise, mathematical propositions such as the statement that “2+2 = 4” is true by definition, by virtue simply of what we mean by the constituent terms “2”, “+”, “=”, and “4”. However, statements that have actual content are not true by definition. For example, the consider the statement that “all bachelors are unhappy.” That might be true, but it also might be false. That is to say, it is a contingent statement. We cannot find out the answer simply by analysis of the constituent terms. It is not an analytic statement. To discover whether it is true or false, we need to gather evidence. And we would never reach absolute certainty of the truth of the proposition since there is always the possibility that we may have missed a bachelor. The statement that God exists and has revealed Himself through the Jesus Christ and communicated to mankind through the Bible is not a statement that is true by definition. It is a statement that is closer in nature to the statement that “all bachelors are unhappy” than to the statement that “all bachelors are unmarried.” The Bible, therefore, cannot simply be presupposed or asserted to be true by “the impossibility of the contrary” as Greg Bahnsen so often liked to put it. The only way to adjudicate the truth or falsehood of Christianity is to examine the evidence.
A yet further challenge to presuppositionalism, often overlooked, is what I call the problem of progressive revelation. To appreciate this problem, imagine that you are a first century Jew, living while the New Testament was first being written. How would you know that the New Testament was a valid continuation of what you already had in the Hebrew Bible? It seems to me that the presuppositionalist strategy would not be very helpful in this situation. Indeed, the only way by which you could know that the revelation concerning Jesus Christ in the New Testament was a legitimate continuation of the Hebrew Bible would be to look at the available evidence.
Finally, another problem with presuppositionalism is that its proponents advocate strongly for demonstrating inconsistencies in alternative worldview systems, in particular atheistic ones. In demonstrating that Christianity alone presents a coherent system, presuppositionalists hope to be able to demonstrate that Christianity is true since all other worldviews are internally incoherent. However, coherence, while a necessary condition, is not a sufficient one for concluding that a proposition is true. For example, the proposition that “the moon is made of cheese” is a perfectly coherent proposition, though a false one. In order to be received as true, a proposition must also correspond to the facts of reality. Therefore, even if all religious systems besides Christianity are incoherent, and even if Christianity is coherent, that does not necessarily entail the truth of Christianity, since it may be that a religious system that nobody has thought of yet is true. There is no reason to think that currently known religious systems are mutually exhaustive, and indeed new ones spring into being all the time.
In conclusion, I am attracted to the evidentialist apologetic system because of both practical issues (I have found it to be most effective at persuasion) and principled ones (for reasons elaborated above). In my judgment, what matters with an apologetic system is primarily its adherence to sound principles of reason and secondarily its persuasiveness. Arguments that are unsound can be persuasive to the uninitiated, and the apologist must resist the temptation to compromise his intellectual integrity by forsaking sound principles of reason for the sake of effectiveness.
 William Kingdon Clifford, “The Ethics of Belief,” in An Anthology of Atheism and Rationalism, ed. Gordon Stein (Buffalo: Prometheus Books, 1980), 282.
 Alvin Plantinga, Warranted Christian Belief (Oxford University Press, 2000), 93.
 Kenneth Boa & Robert Bowman, Faith has its reasons: integrative approaches to defending the Christian faith (Westmont: IVP Books, 2012), 33.
 Cornelius Van Til, The Defense of the Faith (The Presbyterian and Reformed Publishing Company, 1955).
 Greg L. Bahnsen, Presuppositional Apologetics: Stated and Defended (American Vision Press, 2008).
 Scott K. Oliphint, Covenantal Apologetics: Principles and Practice in Defense of Our Faith (Crossway, 2013).
 Cornelius Van Til, Christian Apologetics second edition (The Presbyterian and Reformed Publishing Company, 2003), 124.
 Greg L. Bahnsen, Presuppositional Apologetics: Stated and Defended (American Vision Press, 2008), 21.