How Do You Know?

Throughout history, people have come to different conclusions on this question, how do we know what we know? Now, not everybody has the same approach. Some people are skeptical, saying you can't know anything. Or somebody in our day and age would say the truth is relative and that truth is subjective, and you wonder how you can even have a conversation with people like that, because they're ruling out of bounds any appeal to rationality.

This week on Renewing Your Mind, we're featuring Dr. R.C. Sproul's series, The Psychology of Atheism. He's taking a critical look at the atheist's claim that religion is merely an attempt to meet psychological needs. But many in the academic world take that skepticism even deeper.

They point their guns at the concept of knowledge itself. As we continue now with our study of the psychology of atheism, you will recall that in our last session, I mentioned that the whole question about the existence of God is loaded with all kinds of prejudicial and emotional baggage. Those of us who believe in God have to admit that we want the existence of God to be true. And yet at the same time, we know that in the history of theoretical thought, some of the most brilliant philosophers and scientists have borne strong testimony to their own personal conviction that God exists. You think of St. Thomas Aquinas or Augustine or Warner Von Braun or Albert Einstein, all kinds of people that we could parade as witnesses who carry the credentials of enormous intellectual strength who do not hesitate to affirm their conviction of the existence of God. And yet at the same time, who would deny the intellectual brilliance of a man like David Hume or Jean-Paul Sartre or Ludwig Feuerbach?

We could give a host of names of brilliant thinkers and brilliant scientists down through the ages who have emphatically denied the existence of God. So what does the poor person in the street do when they see these intellectual titans disagreeing over an issue so foundational as the question of the existence of God? Well, it's sometimes the dilemma that people face when they go to their doctor in whom they have great confidence and trust, and the doctor suggests that they have surgery for their malady, and they go and get a second opinion, and another doctor in whom they have great confidence as well cautions against it. And then the person has to try and weigh and balance the credentials of the experts, and you've all seen that in televised criminal trials where you have experts testifying on both sides of the question. So what do you do?

Do you just flip a coin or do you fall back and punt? Well, in the final analysis, we have to test the reasons and examine the evidence and see who is making the more cogent case. But before we embark on that sort of discovery, the first question I think we need to address is even more basic, and that is the question, why is it that people of such great credentials disagree on the question of the existence of God?

Now, we could ask the same question about any issue. Why is it that we find very intelligent people lining up on both sides of a debated point or debated question? Now, we know that there is the fallacy in logic that is called the either-or fallacy, which is the fallacy of reductionism whereby you argue that an issue has to be either this or that when there's another alternative, a tertium quid, as it were. And so the fallacy that is called the fallacy of the false dilemma is when you reduce the options to two when there could be three or four or five options. Well, when we get to the question of the existence of God, there only are two options. Either God exists or He does not. And to reduce it to those two alternatives is not to engage the fallacy of the false dilemma.

He cannot be and not be at the same time in the same relationship. There either must be a God or no God. Now, why, as I say, do people disagree on this question? Well, there are lots of reasons why people disagree about certain things, and we don't have time to explore every conceivable reason why people come to disparate conclusions about issues. But what I want to do is look briefly at the four major reasons why brilliant and capable people end in disagreement on significant issues. What causes these disagreements to take place?

And I'll list them first of all and then give an exposition of each of them. The first reason why people may come to differing conclusions about vitally important questions is that they are operating with different epistemologies. And we'll talk about what that means, different epistemologies. The second reason why people come to differing conclusions about debatable points is the presence of formal errors. The third reason why people come to differing conclusions on important issues is because of factual errors. And the fourth reason, which is the reason we're going to explore most heavily in this brief series, is prejudice or bias.

Now, let's take a look at each one of these individually. The first one I've noted is epistemological differences. Now, before you choke on that word, epistemological, which I know is a somewhat technical term, let me take the time to explain it. In the discipline of philosophy, one of the most important subheadings under the broader heading of the discipline of philosophy is the science or the study of epistemology. And what epistemology is all about is the study of the question, how do we know what we know?

So, an epistemology is a particular theory of knowledge or a theory of how we learn what we learn. Now, we may not use this technical language, but we're aware of the question. How many times have you said something to somebody and they responded to you by saying, how do you know? They're asking the epistemological question, how do you know that? And you say, well, I saw it. I'm an eyewitness, and you are relying now heavily upon a sensory experience. You're appealing to what you saw with your eyes or felt with your hands or heard with your ears. That's part of epistemology. Or you may say, well, the reason I know it is that I figured it out logically or mathematically.

I established my premise and built a syllogism and came to an irresistible conclusion, and so I came to this knowledge rationally. Or you may say, oh, I don't know how I know that. It's intuition, I guess.

I just sort of sensed it in my bones. I don't have time to process the myriad particles of data bits of information, but I'm absorbing them all, and it's going through the mixture of my brain and my own experience, and I'm making a response, an intuitive response. Maybe that's how you answer the question, how do I know? Or you might just appeal to authority and say, I don't know how I know.

I know it, and that's good enough for me. Now, what I say is that people operate on the basis of differing epistemologies. One of the ongoing debates in the history of philosophy has focused on the question of how does anyone know what they know. You've maybe heard terms like rationalism or empiricism or Platonism and Aristotelianism, which have hugely complex structures of thought built in them.

But at the same time, Aristotle and Plato differed fundamentally on the question, how do we know? The 17th century rationalists were called rationalists because they said that the primary way in which people know what they know is through the mind. And they said that the mind has certain innate ideas born with knowledge, a priori knowledge, and that these categories are used to arrange and sort out all of the data bits of our experience into a rational system. Mathematics is heavily rational and abstract in its approach.

The 18th century saw a reaction against 17th century rationalism. Rene Descartes, the father of rationalism, once made the observation that once, through pure logic, he could get to the fundamental ideas of existence, what he called clear and distinct ideas, that he wouldn't have to use telescopes or microscopes to create a worldview. He said he could crawl into his Dutch oven and deduce logically a whole life and worldview. And you remember all of the trouble Descartes went to, to convince himself of his own existence. You've all heard the phrase, cogito ergo sum, I think, therefore I am.

Why would he do something like that? Why would he labor over something that is so self-evident to every other human being? You all believe that you exist. Why would you want to try to prove it?

Well, Descartes was from Missouri. He didn't want to take anything for granted. He said, I want to have a basic principle that is indubitable, something that is incapable of being doubted, something absolutely sure and certain. And he, therefore, went through a rigorous doubting process in a cynical way, doubting every thesis that he could ever conceive of. He even doubted that he could see his hand in front of his face. He said, maybe that's an illusion.

Maybe some demon's making me think I'm seeing my hand in front of my face. It sounds ridiculous to us, but not ridiculous in terms of his own rigorous pursuit. He was trying to say, I want to come to a truth that simply cannot be doubted, that presents the impossibility of the contrary, a truth so plain, so clear and distinct that to doubt it is to prove it. And so he asked himself, while he was doubting, he said, the one thing I cannot doubt is that I'm doubting, because if I doubt that I'm doubting, what am I doing? I'm doubting. And in order to doubt, I have to be thinking, because doubt is impossible apart from thought. And if I'm thinking, there must be a thinker. So, he comes to this rudimentary conclusion, I think, therefore I am.

He says, oh, okay, now I've got a premise to work on. And he's worked all this out logically, because he didn't want to rest his case on what he observed with his eyes or heard with his ears, because he had long ago learned that the senses can deceive us. We can be fooled, we can think that we see something and not really see it. It could be an illusion, or it could be an error in perception. I'm standing in front of a live audience right now, and there's somebody sitting in the third row who used to be a policeman for the city of Chicago, and I'm looking at him and I notice that his head is very small. It's smaller than the nail on my thumb, because if I put my thumbnail in front of my eye and close the other eye, I can obscure his head from my view.

So, from this perspective, it must be that I'm looking at Tom's thumbnail, because his head is smaller than my thumbnail. Now, what's wrong with my thinking there? I failed to take into consideration questions of depth perception, distance, and all of that, but that's the way in which senses can deceive us. And so, Descartes wanted an epistemology that sidestepped all of the problems associated with sensory perceptions. In the eighteenth century, they said, wait a minute, the problem with rationalism is that you can conceive of something's being true logically, and just because it's a logical possibility doesn't mean it's so.

There's nothing illogical about the existence of unicorns, but so far, no one's been able to verify the existence of unicorns by hard data. And so, the eighteenth century empiricists say, unless I can see it, taste it, touch it, or smell it, I'm not going to affirm its existence, because if I want to get outside of my own mind and deal with the world around me, to deal with you, the only avenue that I have from my own mind to you is the avenue of my five senses. My body is the threshold from my mind to the world around me.

The only way I can interact with that world around me is either through seeing it, or hearing it, or tasting it, or smelling it, or touching it. And that's what the empiricists of the eighteenth century were getting at. And so, they said, no, the primacy for knowledge is on the basis of observation and sense perception, not on the primacy of the mind. So, you had two schools of thought that were competing over how we know. Now, take the question of the existence of God. The rationalists would say that the naked reasoning of the mind requires the idea of a first cause and an ultimate being. It's a logical necessity. And Pyrrhus comes at that question and says, it may be logically necessary, but show me Him. Can't see Him, taste Him, touch Him, smell it, He can't be a part of scientific inquiry. I'm oversimplifying at this point in order for us to be able to move along.

But that's basically what the response is. And so, you have differing epistemologies used by different philosophers and how they approach the first question, how I know what I know, will have an enormous bearing on the content they include ultimately in their knowledge. Because if they rule out things that come through the senses or things that are learned through deduction, they have a reduced capacity to grasp the whole of reality.

That's why Immanuel Kant then, after the skepticism of 18th century empiricism, came along and tried to reconstruct epistemology and create a synthesis and show that if we're really going to have knowledge, both the mind and the senses have to be involved in the process. And he said that's the way, in fact, we learn what we learn, that's how children learn, by experiencing things through the senses and by thinking in some kind of logical manner. So that this is why in the scientific method, for example, and when you went to school and your teachers told you that there was a scientific method, what did they mean by method? What does science mean? The basic meaning of the word science is knowledge. So the scientific method is a method or a way of getting knowledge. And classically, the scientific method has two dimensions to it, the formal and the material, the rational or the empirical, the deductive and the inductive. That is, the scientific method rests both on the reasoning processes of the mind and on the gathering and analyzing, organizing and measuring of all kinds of sensory data.

We don't just take pictures of the stars, we also use mathematical calculations and draw inferences from that data using deduction. So both induction and deduction are integral to the scientific method. And that's what Kant was getting, as well as the Enlightenment philosophers who argued that the task of science is to find the logic of the facts.

Now that little expression, the logic of the facts, the so-called analytical method of knowing involves two aspects, the mind, which brings the logical aspect to it, and the compilation of data, which is what are called the facts. Now not everybody has the same approach. Some people are skeptical epistemologically saying you can't know anything. Or somebody in our day and age would say the truth is relative and that truth is subjective, and you wonder how you can even have a conversation with people like that.

Because they're ruling out of bounds any appeal to rationality, because they allow for the possibility of irrational reality. That's a contest that's going on even now in the scientific community, not to mention the theological and the philosophical. So what I've done today is to try to show you that one of the major reasons why great thinkers come to differing conclusions about important issues is that they're operating on different systems of thought. Everyone has a theory of knowledge. Everybody has a way of coming at problems and trying to solve those problems and come to conclusions about issues. Have you ever stopped to ask yourself, what is my epistemology?

I'm the kind of person that asks that question of himself all the time. I keep coming back to the questions of epistemology, how do I know what I know. I sometimes will write a list, ten things that I know I know for sure, because there's so much about which I'm not sure. And then I find I talk to my friends, tell me ten things that you know for sure, and they'll write down their little list of ten things they know for sure, and then I find out that some of them say I know for sure something that's the exact opposite of what I have on my list, and I say I know for sure. I know for sure that regeneration precedes faith, but all my Arminian friends are absolutely convinced that faith precedes regeneration.

But I mean, that's what I'm asking you to do. I'm asking you not simply to write down on a piece of paper the ten things you know for sure, but I want you to think about how you know what you know. Again, the simple question is, how do you know? That's Dr. R.C. Sproul, and I think we get a glimpse there of R.C. 's wonderful sense of humor and the very relatable way in which he taught, the importance of knowing why we know what we know.

R.C. is taking us through his series, The Psychology of Atheism, this week on Renewing Your Mind, and we're glad you could be with us. In Fifteen Lessons, R.C. explains that the issue is not intellectual, it's moral.

As the apostle Paul tells us in the first chapter of Romans, sinful man suppresses the truth about God and seeks to live in unbounded freedom. It's important for us as believers to be equipped to respond to the claims that atheists make, so I hope you'll request our resource offer today. When you give a donation of any amount to Ligonier Ministries, we will send you Dr. Sproul's book, If There's a God, Why Are There Atheists? We'll also provide you with a digital download of the full series that we're hearing this week.

There are 15 messages in all, and you can request them when you go online to renewingyourmind.org or when you call us at 800-435-4343. One of our teaching fellows, Dr. Stephen Lawson, weighed in on this issue at one of our Ligonier conferences, and let's listen to what he had to say. Now there are different kinds of atheists. There is the intellectual atheist who claims that there is no God, but in reality he knows that there is God. There is also the religious atheist who has said no to the one true living God as presented in the Scripture and chooses to go after gods of his own making or gods who have been invented by other men. And then there is also the practical atheist who actually believes that there is a God but chooses to live his life independent of God. That's helpful to know as we interact with skeptics and those who claim to be atheists. This really underlines our goal at Ligonier Ministries to help you know what you believe, why you believe it, how to live it, and how to share it. If you'd like to continue your study, I hope you'll contact us soon and request Dr. Sproul's book along with a digital download of the series we're featuring this week.

Our phone number again is 800-435-4343, but if you prefer to go online to make your request, our address is renewingyourmind.org. Well here's a preview of Dr. Sproul's next lesson. We as human beings, as well trained as we may be in the science of logic, are still capable of making incorrect inferences and errors in deduction. And that's one of the reasons why great minds will come to differing conclusions about significant issues because somewhere along the way, somebody's made a logical leap, and so they come to a different conclusion. I hope you'll join us tomorrow as we continue the series, The Psychology of Atheism, here on Renewing Your Mind. Thank you.