Reliability of Sense Perception

What were senses of taste and touch and smell tells about each other and about God.

I cannot have any thoughts about you or about the world or anything outside of my mind except through my senses.

So, as imperfect as my senses may be.

That's the only avenue.

I have two reality outside of myself is true that our senses connect this to the world around us, but it's also true that our senses aren't always trustworthy to give us false information at time we have to conclude that our senses can't be the ultimate source of truth, but can they give us some truth there is Dr. RC's broad continue. Once again, now with our study in Christian apologetics and were in the middle now of looking at those elements of knowledge of the science of epistemology that are essential to coming to a sound defense of the truth of theism, and we've looked first of all, at the law of non-contradiction in our last session we looked at the issue of the law of cause and effect or the law of causality and we were careful to show that the proper definition is important to this whole discussion that the law causality is defined in this way that for every fact there must be an antecedent costs now today I said that we would look more carefully at the critical analysis of causality that was offered by the 18th century Scots philosopher David Hume, David Hume, in his inquiry into these matters of causality made some observations about cause and effect that are very important.

Under his analysis.

He said this, that what we observe. When we see things happening around us are what he calls relationships that are customary customary relationships or another term that he uses was relationships of contiguity.

You know that if you have a house and you have a property line that the house next door may be said to be contiguous to your property because it abuts a right up next to it so that which is next to something else would be contiguous to it. So what David Hume is saying here is that we see events transpire or take place in the external world that one thing follows another and we assume that the one thing causes that which follows it, because they follow in sequence on a regular basis.

We see for example on a regular basis that it rains and when it rains, the grass gets wet so that there is a customary relationship between raining and wet grass. And this happens in such regular sequences or intervals that we come to the conclusion that the cause of the grasses becoming wet is the reigning receipt now you look at me and you say somebody really raising a question of whether the routine is causing the wet grass. Everybody knows that the rain is that which causes the effect of wet grass well in ordinary experience. That's the way we think, because that's the way it certainly seems to us under the naked vision that we have in our observations and because we are accustomed to thinking in this way, but how do we know that in between the falling of the rain and the dampening of the grass some invisible cause other than the rain is interceding and is the real cause for the grasses becoming wet now.

Again, that may seem like utter stupid assumptions us like speculating about men made of green cheese on the backside of the moon and so but from a philosophical perspective, particularly in light of the 17th and 18th century, when philosophers were doing a penetrating analysis of understanding external reality and the forces that are in effect making happen what makes happen with the school of Descartes with his theory of interactionism and with other philosophers such as Spinoza and Leibniz in the rational school who postulated invisible causes that were not seen for that which you can observe empirically and so there was a big controversy in science and in philosophy about actual because it see if I can make something of an illustration right now what is it that makes us sick from time to time. Keep in view that now when we are ill or something.

We might go in and get blood test done were throat cultures and these cultures are placed under microscopes and we begin to discover that organisms are antibodies are at work infecting our well-being that are invisible to the naked and without the discovery of microscopes and that sort of thing we never would've imagined that the causes for our diseases are what they are presumed to be now and it wasn't that long ago where people talked about animal spirits invading our bodies and going up and down our arms and so before the use of the micro scope so again with the microscope is done as opened up a whole new world of realities that are truly there and are making an impact on our lives and their flying around in his room right now that we can even see we say well we picked up a bug or germ or someone I had the flu last week and somebody told me the second day of the flu that it was a 24 hour bug and I serve with my 24 hour bug needs a new wristwatch that cuts the still here but we talk about bugs and we talk about these things that infect us, but what Hume was doing from a scientific analysis was there's all kinds of things going on that we don't perceive we don't ever really see and we make assumptions that because one thing follows another.

It is therefore the cause no causal thinking.

Ladies and gentlemen is at the heart of the scientific inquiry. It's at the heart of medicine when were ill and we go to the doctor and we asked the doctor for a diagnosis were asking him to determine and isolate the cause for our illness and we want him to be able to determine the cause so that he can come up with a treatment that will cure the disease. But if we can't determine what's wrong and don't have a proper diagnosis is very difficult to find the proper remedy and not only that, but in biology and chemistry in physics and astronomy.

The principle of causality is assumed constantly. Said another way, causal thinking is that the heart of natural science. Now you can imagine, the crisis that came about in the 18 century when this very learned scholar in Scotland raised questions about scientific ability to determine and isolate causes. Now in his analysis of this David Hume used a famous illustration and the illustration was what we call the pool ball illustration. If you can imagine a pool table and is a pocket at the end of the table and in the middle of the table you have the two ball and then you have the object ball will call the eight ball and the object here is the pool player wants to sink the eightball in the corner pocket and so he picks up the cue stick with some chalk on the end of the stick and he aims the cue stick at the cue ball gun and then using the motion of his arm. He swings the cue stick and it moves the cue stick. The CUSIP strikes the cue ball imparting force, presumably to the cue ball setting the cue ball in motion and the cue ball moves across the table until it hits or collides with the object ball. In this case the eightball and then immediately following that the eightball begins to move an FRA name and striking or correct improper. Ultimately the object ball is deposited in the corner pocket. But you see all kinds of physical actions involved in that. I pick up the cue stick. I aim the cue stick. I swing my alarm and since my arm is connected to the cue stick the cue stick moves when I move the cue stick. I hit the cue ball with the cue stick and then the cue ball hits the object ball and so we make the assumption that there is a causal relationship in sequence all along here but there's anybody actually perceive invisible force transferred from the end of the cue stick to the cue ball. Does anybody see the transfer of force from the cue ball to the object, but no what you see is one thing following another and that is what's called a customary relationship or a continuous relationship and what Hume is saying is you don't see causality, you see several actions taking place in sequence and your assuming a causal next Zeus or a causal relationship from those distinct act in the old story of the farmer who is awakened every morning before he wanted to wake up because at the crack of dawn, the rooster crow and he said no every time that rooster mind crows.

The sun comes up and it gets in my eyes coming in this window and it wakes me up and so if I want to stop the sun from coming up.

I'm just going to strangle at roost because he's but like Joel rooster I can stop the sun because every day the rooster crowed.

Then the sun And he assumed that it was the rooster causing the sun to come up and that's an example of a fallacy that we learn an informal fallacy in the science of logic called the post hoc ergo proctor of fallacy, which being translated means the fallacy of after this, therefore because of this that just because something happens after something else does not mean that the previous thing had any thing to do with that which came afterwards and you can't just assume because one thing follows another that they are connected causal. Now that's a brief overview of David Hume's analysis of the problems of causality. Now what happened was, you have all kinds of people who have assumed that there is a kind of a causal leap with their minds who have assumed that what Hume did with this analysis was demolish the law of causality, which he did not do, and he actually himself came to the conclusion since we can't know what is causing a particular fact we might come to the conclusion that anything can produce anything else that's fine if he wants to talk like that.

However, what he doesn't show is that nothing is causing the movement of the pool ball. It's one thing to say, there are forces engaged here that I don't perceive that I can't see it's one thing to say. I don't know what's causing the motion and it's a huge movement from that to say nothing is causing the most. Again, when we apply the law causality to the external world. We have to face the limitations of sense perception that David Hume sets forth, but we don't have to. Therefore, jettison the principal of the law of cause and effect because it still remains a fact that if something is in effect, it was indeed caused by something other than itself. That has to be true no matter how many experiments you take, because again I remind you that is a formal argument. Now remember that the third principle that I talked about was the principle of the basic reliability of sense perception and I labored the point that we admit that our senses do not have perfect perception of reality. That's why we have machines to heighten our ability to perceive things like telescopes and microscopes.

As I mentioned before and remember I mentioned illustration of Augustine's bent or in the water and somebody's head being the size of my thumbnail because I can cover their head from a distance with my thumb and understanding principles of depth perception and that we understand there are limits to our powers of perception. Now what David Hume does here is shows those limits that we never can penetrate to the invisible realm where perhaps all kinds of unseen forces are at work, not the least of which is the power of God. Again the New Testament tells us that in God we live and move and have our being, not just take that second part of that in God we move and one of the principal assumptions of Christian truth is that nothing can move in this world apart from the power of God and I can say I have the power to drop this piece of chalk and make it move but it best on the secondary cause because I can't even open my finger apart from the power of God and the power of God is invisible. So the other side of the coin is.

This is an argument that is compatible with Christian theism that says there can be no power without God and that God is the power supply of all motion and because he's invisible. No amount of empirical research will get to the heart of the matter to get to the heart of matter, to get to the heart of the motion of Matt and so in that regard, I have no complaint with David Hume's analysis where he shows the limits of human sense perception.

Unfortunately, he took it to this place where he tried to reduce all science that depends upon sense perception to skepticism.

In fact, it is said of Hume that he represents the graveyard of British empiricist Immanuel Kant, who came after Hume said it was Hume's skeptical analysis of being able to perceive causal forces that awaken Kant from what he called his dogmatic slumbers and can't set about his whole rest of his career to rescue science from pure skepticism because if you demolish causal thinking. It's not just Christian theism that goes it science that goes and so Kant sought to resurrect the validity of causality in the basic reliability sense perception again. My senses cannot give me a comprehensive view of reality. But the only link I have from the interior chamber of my mind I think to the external world. The only transition I have from the mind to you through my senses. My body is the bridge from my mind to the world.

What is mind Dr. Gerstner used to answer the question what is mind, no matter what is matter than never mind what he was getting at with his cute little game was that there is a fundamental distinction between materiality corporeality and that which is non-physical and an idea a thought in the mind may be linked to a physical cause of chemical stimulations and synapses and so on.

In the physical surface of the brain, but it's one thing to say. The physical brain gives rise to thinking it's another thing to say that thinking itself is physical and we don't want to do that. Okay so I'm saying is that my syncing my conscious awareness of things is nonphysical, but I cannot have any thoughts about you or about the world or anything outside of my mind except through my senses. So, as imperfect as my senses may be. That's the only Avenue I have two reality physical reality outside of myself, I can retreat into my own mind and make all kinds of deductions about what may or may not be out there, but I have no actual contact with the world out there, except through my senses. That's why it's axiomatic in modern science and in biblical studies to operate with the assumption that our basic equipment that we have the faculties of knowing that God is given us such as seeing, hearing, tasting, smelling, touching, and so on are at least reliable enough for us to act upon again when I see the light turned red. I can speculate that maybe a demon because that works a malfunction in that's possibility, but I trusted enough to put my foot on the brink and this is the way the Bible speaks when it talks about.

As I mentioned earlier Peter saying we don't believe in cleverly devised myths or fable, but we believe in what we have seen with our eyes and heard with our the basic reliability of sense perception and even the assumption that we can see causal relationships in this world is assumed. Throughout Scripture, and so these three principles are nonnegotiable to Christian apologetics again the law of non-contradiction law. Causality three. Basic reliability since seeing and hearing used God's design is ordained or senses as means of knowing who he is.

Our study this week on Renewing Your Mind is from Dr. RC Sproul series defending your faith in 32 messages RC surveys the truth claims of the Bible and makes a solid case that logic is a helpful ally in defending them. We like to send you the series of 11 DVDs simply requested today with your donation of any amount to litigator ministries. You can reach us by phone at 800-435-4343 or online at Renewing Your Mind.Ward were also including a 12 bonus disc that contains the MP3 audio files of the series, and a PDF of the study guide that contains additional reading suggestions study questions and an outline of each message. We hope to hear from you soon again.

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