Science has fundamentally altered our standards of what counts as knowledge. We turn to science when we think of rigorous investigation. We contrast science with mere opinion. We have, to some extent, allowed science to set the standards for many other disciplines. Today, some may wonder, “do we really have knowledge beyond science?”

What does “science” mean?

It is important to consider what it is that we mean by ‘science’. The English-language word ‘science’ derives from the Latin ‘scientia’ meaning ‘knowledge.’ In its broadest sense, we might see ‘science’ as simply knowledge established through rigorous investigation. Usually, however, we understand ‘science’ in a more narrow sense (e.g. the study of the natural world). Sometimes the notion of science is used in a more methodological sense: knowledge established by repeated experiment. We sometimes hear reference to the ‘scientific method.’ However, perhaps the most common use of ‘science’ is in an institutional sense: all that has been accomplished both in knowledge and technical achievement by the investigators, laboratories, publications, and institutional bodies that are devoted to the study of the natural world and to the applications of the resulting knowledge.

So what is the relationship of science to what we know? Do we really know anything beyond what science delivers? Certainly science has given us remarkable achievements: an understanding of the laws of nature, an extraordinary capacity to predict, and technological advancement that is genuinely mind-boggling. What other set of academic disciplines can boast such achievements?

Many questions fundamental to human life and meaning simply are not subject to the scientific method.

Is science the only route to truth?

We may be tempted then to rely on science, and on the scientific method, to establish all knowledge. This, however, would be a mistake. Science is not the only source of knowledge. Many questions fundamental to human life and meaning simply are not subject to the scientific method.  For example, while the natural sciences can often proceed by repeated experiment, history cannot. The past is not subject to experiment and replication in the same way a chemical reaction is.  In general, questions about history, about what occurred in the past, are only accessible through different modes of inference, through circumstantial evidence, through the synthesis of such evidence, or through inference to the best explanation.

There is, for example, broad consensus that Julius Caesar died in the year 44 BC and almost certainly sometime within the fifth decade BC, between 40 and 50 BC. This is generally accepted as knowledge. But is this science? Well, it is not established by repeated experiment. Julius Caesar’s death was a singular event. It is thus not something we can replicate. So how do we know it is true? Well, we have inscriptions that suggest it is so, we have other evidence about the relationship between his death and various other events, and we have relatively early written accounts of his life. Is it possible that all of this evidence points us in the wrong direction? Well, maybe. But it does seem rather unlikely. We would have to come up with a very convoluted explanation indeed to explain how all of the evidence points to 44 BC but that this is entirely wrong.  Perhaps we cannot establish this with absolute certainty, but we can be pretty sure.

How can different kinds of knowledge be verified?

What we have seen with history, in contrasting it with the natural sciences, is that different types of knowledge admit differing levels of certainty and require different methodologies for verification.  In terms of its ability to establish things with certainty, at the top of the hierarchy is, arguably, mathematics and philosophical logic.  Mathematical knowledge follows logically from premises to conclusions. Next would be experimental science: repeated experiment subject to control and replication. This is arguably the methodological approach which has given the natural sciences their strength; it is generally reliable and powerful. Next would be observational science, the collection of data subject to some degree of replicability and some degree of control, but not entirely within the power of human manipulation. This is the mode of inquiry often used in many social sciences such as sociology or political science. It is the primary mode of inquiry used in my own discipline, epidemiology, but it is employed also, as we will discuss, in some aspects of the natural sciences. Following this would be historical knowledge: the collection and synthesis of pieces of evidence from the past, often concerning a singular event. Such an approach generally has less potential for replicability. Finally, we have philosophical and theological argument. Such arguments sometimes concern what is implied about reality from the way we use language and concepts, or from the structure of our minds; or alternatively, such reasoning may try to present a comprehensive framework that in some way makes sense of our world and human experience.

So we have our hierarchy of modes of inquiry with regard to the degree of certainty that can generally be established: mathematics and logic, experimental science, observational science, historical inquiry, and philosophical and theological argument. Some disciplines cut across these classifications. Biology, for example, involves experimental, observational, and in some cases, even historical arguments. Social sciences, such as economics and sociology, which have traditionally relied primarily on observational methods have increasingly moved towards experiments; in psychology experiments are now perhaps primary. Different disciplines thus sometimes employ different methodologic approaches, and we should generally classify the strength of evidence according to the method of inquiry rather than the discipline itself.

Nonetheless, science has achieved considerable standing within the academy and also with the general public. And there are many good reasons for this: much of science relies on experimental methodologies. It has often been possible to establish substantial consensus. And science has given us considerable predictive power. It has allowed for remarkable technological advances. The natural sciences have also often been subject to greater rigor than many other disciplines, due to replication, commonly accepted methodologies, and very high standards in the review of research.

Many questions, those that are most relevant to human existence, require methods and modes of inquiry that do not allow for scientific levels of certainty. If we ask questions like “What am I to do with my life?”, “Does my spouse really love me?”, or “What is justice?”, science does not provide answers.

What methods do I use to test knowledge?

Most of my own research involves either the first level, mathematics, in the development of new methods, or the third level of the hierarchy, observational research in epidemiology, though I do occasionally work with experimental data, the second level, from randomized trials in medicine. Although these modes of inquiry establish the greatest levels of evidence and certainty, I do, nevertheless, strongly believe that some of the most central questions about our lives require other approaches. Many questions, those that are most relevant to human existence, require methods and modes of inquiry that do not allow for scientific levels of certainty. If we ask questions like “What am I to do with my life?”, “Does my spouse really love me?”, or “What is justice?”, science does not provide answers.  These are important questions for which only observational, historical, and often, only philosophical or theological arguments are possible. When we think about some of the things that are most important to our lives—“How do I decide what is right and wrong?”, “Does my life have meaning?”, or “What happens to me after I die?”—suddenly our hierarchy with regard to the strength of evidence may be flipped with regard to the importance and centrality of these questions to our day-to-day lives. Many questions which are important—central to life— cannot be addressed by science and must by left to other modes of inquiry.

When we turn to these other approaches, there is often much more room for legitimate disagreement. Well-meaning, honest, intellectually astute people can and often will disagree. This does not mean that rational argument and evidence have no place in these questions, only that we need to be realistic in what can be definitively established. Much evidence and argument in historical, philosophical, and theological inquiry is “inference to the best explanation.” What explanation best accounts for the data, the facts, and the evidence available? Often such inferences will only be tentative. Agreement may not be possible. But even here, in many cases, considerable consensus can be established and evidence can still be relatively strong. There is strong evidence and general consensus for the death of Julius Caesar in 44 BC. This is historical evidence and historical knowledge. Sometimes we cannot establish consensus or convincing evidence from historical or philosophical arguments. But sometimes we can.

I really do think any educated person in America should, at some point, have critically examined the claims for Christianity and should be able to explain why he or she does, or does not, believe them.

What evidence is there for the claims of Christianity?

Here I would like to present and examine the evidence, as I see it, for some of the central claims of the Christian faith. The evidence is not water-tight. It is a combination of historical and philosophical evidence. Much of it involves arguments in the form of inference to the best explanation. There is legitimate room for disagreement. But I believe some of the arguments are, in fact, quite strong.

So why should you care about this? Well, in my view, every student passing through university should critically examine such evidence for themselves. Why do I think this? First, Christianity has shaped, and continues to shape, Western history, culture, and thought, and increasingly, world-wide history, culture, and thought. Second, Christianity makes truth claims, and I believe university life, with its intellectual freedom, is an ideal context in which to examine these truth claims. Third, if the Christian faith is true, it is important; it has implications for all of life. I really do think that any educated person in America should, at some point, have critically examined the claims of Christianity and should be able to explain why he or she does, or does not, believe them. It sometimes truly does amaze me that we do not discuss these things more often.

In our limited time here, I am not able to set out a complete argument for the Christian faith and critically evaluate the objections and potential responses to the claims that are made. What I do hope to accomplish, however, is to convince you that there is evidence worth examining—that Christianity is not simply a matter of weak-minded individuals gullibly believing a series of nonsensical stories, but rather that there is serious evidence that lends at least some, possibly substantial, credibility to the Christian faith. Like with many historical and philosophical questions, there is legitimate room for disagreement as to where the evidence points, and in the end, you may well come down at a different point than have I. But the evidence itself is worth examining, and doing so, I believe, may prove very valuable. So, let us begin.

Evidence for the existence of God

A number of philosophical arguments have been put forward for the existence of God. Some of these are referred to as arguments from design. Does the complexity of our world, of human persons, of our mind and language, somehow point to a designer?  The question is disputed; arguments are put forward on both sides and some of these arguments have become increasingly philosophically sophisticated. We cannot go into them all here, but they are thought-provoking if nothing else.  A variant on these arguments is sometimes referred to as the “fine tuning” argument. Certain constants in physics (such as the ratio between the strengths of the forces of gravity to electromagnetism) must lie in a very, very narrow range for there to have been any possibility of life to emerge in our universe. And, as it turns out, these physical constants do in fact lie in this very narrow range, and we do indeed have life. Physics does not dictate these constants be any particular value,  yet they occupy this narrow range that is required for life. Is this itself evidence of a creator?

Other philosophical arguments for the existence of God concern what is sometimes called an argument for a “first cause.” The arguments generally run something along the lines of the following: if every event has a cause, then, if we are to avoid an infinite regress of causes, there must have been a first cause. Was this God? Similar arguments involve matter or time rather than causes. So far as I understand it, there is also general consensus in physics that the universe had a definite beginning; and that an infinitely expanding and contracting universe is not possible as it would not be consistent with the second law of thermodynamics (which entails increasing entropy). If the universe had a beginning, who or what set the universe in motion to begin with? Again, was this God? As I see it, many of these arguments concerning an infinite regress, or the beginning of the universe, boil down to the question, ‘Why is there something rather than nothing?’ Or, ‘Is God a more plausible hypothesis than a self-explanatory universe?’ Different people do interpret the evidence differently and answer these questions in different ways, but the questions and arguments are nevertheless suggestive and worth considering.

Evidence for the resurrection of Jesus

A different line of argument, an argument for Christianity itself, and, for me, the one that is most convincing, is examining the historical evidence concerning what happened around the time of the death and supposed resurrection of Jesus. These arguments are presented in many forms. They are presented in popular forms by Christian apologists such as Josh McDowell or Lee Strobel. They are presented in somewhat more sophisticated philosophical forms by some scholars, like William Lane Craig. They are presented in a more historical form, taking biblical criticism quite seriously, by others such as the theologian Wolfhart Pannenberg. Pannenberg begins with what is arguably established by historical critical research and proceeds from there. He does not begin by assuming that the Bible is authoritative. He believes that the Christian faith ought not be given any type of special status in rational inquiry but that its truths need to be argued for and established. So let us take a look at these arguments.

The arguments are in the form of inference to the best explanation. These arguments essentially consist of noting that any explanation for what occurred around the time of Jesus’ death must explain the existence of two sets of testimonies. First, appearance testimonies: that Jesus was supposedly seen by his disciples and others after his death. And second, empty tomb testimonies: that the tomb in which Jesus was buried was supposedly found empty.

You may not believe that Jesus was seen by his disciples, or that his tomb was empty, but it is clear that there does exist testimony to these things. The testimony may be wrong; the tomb may not have been empty; the appearances may not have occurred; but the testimonies themselves of the appearances and of the empty tomb need explaining. Of course, one explanation is that these details were fabricated, but there are other potential explanations as well. So let us take a closer look at these two sets of testimonies.

Let’s begin with the appearance testimonies. What are these traditions or reports exactly? Probably the earliest of these reports appears in a letter written by Paul, a convert to Christianity some time after Jesus’ death. Paul, in a letter written to a local church in Corinth, written maybe twenty years after Jesus’ death, reports that after Jesus died, he later appeared to the apostle Peter, then to all twelve of Jesus’ disciples, then later to five hundred people at once, later still to others, and finally, to Paul himself. These appearances supposedly took place at quite diverse times, with at least three distinct temporal groupings. Paul also claims in this letter that many of the five hundred to whom Jesus appeared were still alive, and thus, could have potentially been questioned on the matter. One may not believe that these appearances took place, but we still need to explain why Paul claimed they did. So there are claims that Jesus’ disciples, Paul himself, and many others saw Jesus after his death. What might explain these claims? First, maybe they did see him, or, second, maybe they thought they saw him but in fact didn’t, or, third, maybe they fabricated these claims. Are these different explanations reasonable? We’ll return to this question.

The other set of testimonies that needs explaining are those of the empty tomb. Scholars generally think that the gospel of Mark, written maybe twenty or thirty years after Jesus’ death, is the earliest written account of the empty tomb, building on earlier oral accounts. The empty tomb stories appear in the other gospel accounts of Jesus’ life as well, and are also presupposed, to a certain extent, in Paul’s writing. In addition, the earliest arguments against Christianity do not deny that Jesus’ tomb was empty but rather claim that Jesus’ disciples stole the body. Accordingly, we have these empty tomb testimonies that need explaining. And, once again, we are left with three options. Either Jesus’ tomb was empty, or the disciples thought it was empty but it really wasn’t, or the testimony is based on a fabrication.

Let’s take a closer look at these possibilities. With the empty tomb testimonies, maybe the disciples were just a little deluded or plain wrong. Maybe the disciples went to the wrong tomb, or maybe Jesus was in fact never buried; so they thought there was an empty tomb when in fact there wasn’t. While such possibilities cannot be definitively ruled out, there would have been considerable motivation for the Jewish authorities to find the right tomb or to produce the body. If the tomb had not been empty, the disciples’ claims of resurrection would then have been quickly refuted. Moreover, we find instead that the early arguments against Christianity were not that it was the wrong tomb, but rather that the disciples stole the body. So maybe fabrication instead of delusion; we’ll return to this. What about the appearances? Might the disciples have been deluded and thought they saw Jesus raised but hadn’t? Might these have been visions or hallucinations? Well, the appearances supposedly happened to many different people, and even at several different times. Mass hallucinations seem unlikely; those occurring over many different periods of time seem even more unlikely. Mass hallucination and delusion may be a stretch.

So again, maybe the claims were fabricated. On the face of it, this might seem like a reasonable explanation but several things make it difficult to completely dismiss the claims as fabrication. First, Paul claims five hundred people saw Jesus at a single appearance after his resurrection, and he claims further that many of these five hundred were still alive when he was writing. This would be a strange claim to make if this were entirely a fabrication—much better to keep the supposed appearances restricted to a much smaller group as it is easier to cover up the fabrication. Paul seems to assume that if the readers of his letter were to question this large number, they would indeed all testify to having seen Jesus. Second, Jesus’ disciples appear to have been disappointed, dejected, and fearful following Jesus’ death. They certainly did not expect their leader to die by the hands of their opponents. But somehow, after their disappointment, within a short period of time, their fear had seemingly been transformed into a message of Jesus’ resurrection. Did a fabrication do this? Well, eleven of the twelve disciples apparently died for their belief that Jesus had raised. If the appearances were fabricated, then not one was willing to give up this fabrication to preserve his life.  Finally, it is difficult to explain Paul’s conversion without a resurrection appearance. Paul had been persecuting Christians and suddenly, he became an evangelist for the Christian message. Further, he himself claims that it was an appearance of Jesus that led to his conversion. Maybe this, too, was fabricated, but why did Paul then convert in the first place? He, too, was severely persecuted for this beliefs. What exactly motivated the disciples to begin with when they were so fearful and when they were so severely persecuted for such a fabrication? What was it exactly that had transformed them? The explanations that the appearance and empty tomb testimonies were fabrications, or hallucinations, although certainly not out of the question, do have at least some compelling evidence against them. If the appearance and empty tomb testimonies were not based on hallucinations, or on fabrications, then what did occur? Might the testimony have been true?

 What one concludes depends in part on one’s preconceptions, and it can be difficult to give up preconceptions. But there is evidence. And it is worth thinking about. It is worth taking seriously.

Questioning our preconceptions

The arguments are not water-tight. What exactly occurred cannot be definitively established. But these are not questions of the natural sciences. These are questions of history; these are important questions, but ones for which we cannot have certainty. What one concludes depends in part on one’s preconceptions, and it can be difficult to give up preconceptions. But there is evidence. And it is worth thinking about. It is worth taking seriously. Wolfhart Pannenberg, whose form of these arguments deeply engages with historical scholarship and critical research, concludes that all naturalist accounts of the appearances and of the emergence of early Christianity seem to fail. He argues that if the historian does not pre-judge the matter by assuming “the dead cannot rise,” then there is, in fact, strong evidence for the resurrection. As long as the historical method does not rule out, from the beginning, that dead people do not rise, then the resurrection, he argues, can be seen as the best explanation for the facts that are established. I do not dispute that there are other potential interpretations of the evidence at hand, and that some of where one comes down depends in part on how strongly one’s prior beliefs are that “such a thing as the resurrection simply could not happen.” All I want to suggest here is that there is serious historical evidence, and the evidence is worth examining seriously.

Are we willing to explore?

And taking a careful look may lead to surprising places. C.S. Lewis, a scholar of Medieval and Renaissance literature, a novelist, and an eloquent expositor of Christianity, began as something between an agnostic and an atheist. He continued as such until he considered seriously the possibility of the truth claims of Christianity. Examining the evidence critically led to his conversion. Lee Strobel and Josh McDowell, both popular Christian apologists, who have written on arguments for the historicity of the resurrection in accessible formats, likewise both began as atheists—atheists until they looked at the evidence. This is not the story of everyone, but it is the story of many. We must ask ourselves, then, are we committed to truth wherever it may lead us? Are we open to forms of inquiry beyond science? Are the Christian truth claims, if they hold up, important for life? Are they worth examining? And am I willing to examine them?

Tyler VanderWeele is a professor of epidemiology at Harvard School of Public Health.