Evidence for the Soul

Author Greg Koukl Published on 04/24/2013

An apocryphal story of Greg’s backyard deck serves to illustrate an important lesson about the nature of human identity.

I’m having a dispute with my neighbor and I want you to help me settle it. I need your advice, because I want to keep good relations with my neighbor, but at the same time, I think he stole something from me, but I’m not sure.

My neighbor and I both have decks in our back yards. In fact, our decks are exactly alike, almost. He built his long before I built mine. I liked what I saw, so I made one just like it, according to the exact same plan. I put it together with screws, just the way he did. But there was one, big difference. I used this new wood-polymer product called Trex which doesn’t splinter, rot, warp or split. It looked great.

So, our decks looked identical, except that my was beautiful Trex and his was splintered and weather-beaten.

Well, I got back from being out of town one week and I noticed that a bunch of the planks of my deck had been removed and replaced with planks that were all worn out. When I looked over my fence, I noticed that my neighbor had beautiful Trex planking in the exact same spots that my deck had the old planks. Does this look suspicious or what?

A few days had passed before I had a chance to talk to him. I noticed that a lot more planks had been transferred. Then when I got back from Chicago two weeks ago I looked out in my back yard and, low and behold, my entire deck looked like his used to look, and his looked brand new with that beautiful Trex material that doesn’t splinter, rot, warp or split.

I think my neighbor stole my deck. But he says he didn’t. Now, he admitted that he exchanged the boards. Here was his explanation. Can you believe this?

He said,

“No, that deck in your back yard is still the same deck. It still has the same shape. It’s located in the same place. It underwent some change, but the change was piece by piece. Therefore, it’s still the same deck—your deck—even though it now looks a lot older.”

I said,

“Listen, if I have a lawn chair in my possession that is constructed of all the exact same physical parts that yesterday made up your lawn chair, even if I disassembled it on your property and reassembled it piece by piece on my property, it’s still your chair, right?”

“Just because this deck was reassembled piece by piece in the same place—my backyard—it’s not the same deck because it’s made out of completely different stuff—your junky wood. And you want to say that just because that beautiful thing you now call ‘your deck’ is still in the same place in your yard and underwent its transformation piece by piece, that even though it looks different it’s still the very same deck, and therefore you own it?”

“You’re nuts. Anyone can see that if you change all of the parts on my deck, it’s no longer the same deck. It’s a different deck. Period. I’m studying philosophy. I know how that works. I know about personal identity. You can’t pull the wool over my eyes.”

Here’s my question to you. Do I have a case? Whose deck is in his back yard? Did he steal my deck?

Now, I have a confession to make. This didn’t really happen. It’s a story. But there’s a very important lesson here about the nature of things, especially the nature of identity regarding physical things. If I smashed a chair to pieces, the physical stuff would still remain, but the chair would be gone. Purely physical things can be destroyed simply by disassembling them in some way.

A physical thing’s identity is determined by its precise physical makeup, the assembly of particular physical parts. If you change any of the physical parts of a thing, it’s not really the same thing, as a whole, that it was before. And if you change all of its physical parts, there can be no question in your mind that you don’t have the same physical thing anymore. That’s why it was no longer my deck in my back yard. He stole it from me.

If you’re clear on this, then I want to ask you the question I asked a young man at Cypress College last week. I was giving a lecture on the relationship between faith and science and whether there was a necessary conflict between the two. During the Q&A afterwards one young man got very hot under the collar and loudly challenged just about everything I’d said.

Now, he didn’t argue with me—I’m choosing my words carefully here—he yelled at me. It wasn’t an argument because he gave no reasons why my view was not accurate. He just kept telling me I was wrong, wrong, wrong, that science gave us facts about the world and religion was just silly opinion that no one could ever properly claim was true.

His point was, only science can give us true information about the world. Theology can’t, not even in principle.

I asked him why he believed that, what were some good reasons I should believe his view that religious claims could never be shown to be true, even in principle. There was an embarrassing silence, because he had no reasons to give. I asked him again. He accused me of twisting the issue and then loudly recited his opinion, without support, without reasons, without defense (which is a common tactic).

So I asked him this question, in true Columbo form: “When were you born?” More silence. He didn’t trust the question because he didn’t know where I was going with it, so I asked again.

“Come on, when were you born?”


“What day?”

“May 1.”

“So you were born on May 1, 1975?”

“That’s right.”

Then I asked my follow-up question. “Is the body you possess today the same body you had on May 1, 1975?”

Again he balked. He tried to say it was, but then I pointed out that his physical body was quite a bit larger now, it has a different appearance, and it has different qualities. More to the point, it’s made up of completely different physical stuff. In fact the molecules in our bodies are almost completely exchanged every seven years. So at 21 years of age he’s had at least three completely different physical bodies. Just like the deck, it’s not the same thing any more.

I then pointed out the conclusion that was beginning to dawn on everyone, including him.

“If you were born on May 1, 1975, and your physical body in front of me right now did not even exist as a physical body in 1975, then you are not your physical body, are you?”

“That’s totally irrelevant!”

Why? Because it’s not a scientific argument.

This man characterizes the tendency of some to simply ignore good arguments they don’t want to deal with or aren’t capable of answering (or maybe never even thought about). You’ll never hear, “Boy, that’s an interesting point and I don’t know how to answer it. It seems to make your case, but there might be something wrong with it. Let me think about it for a while to see if it’s flawed.”

No, they won’t do that. Instead, they resort to the steamroller. They overpower you with noise, aggressiveness and simple, unthinking denial.

Listen, if there are good arguments for something, and no arguments against it, then you have a rational obligation to believe it, at least until other evidence surfaces. That’s the way clear thinking works.

But in this case any argument was going to be irrelevant. Why? Because he was convinced of his own point of view regardless of evidence and regardless of reason. Nothing I said would ever make a difference. Some people are like that. Don’t let it be you.

Here’s the question. What is it about human beings that allows us to maintain our identity over time—such that we can say we’re still ourselves—even when we go through such radical physical changes that we can have entirely different bodies?

I’ll give you a clue, the same clue I gave to the young man at Cypress College: it’s not anything physical. Why? Because all the physical parts are replaced piece by piece every seven years. If you’re 42 years old you’ve had 6 completely different bodies. Can you ever possess a different body? Sure. You do it all the time.

What is it that makes the difference? If it’s not something physical, it must be something non-physical. That’s simple. You are not physical. You are a non-physical something that sustains its identity through time even though the physical body you possess and use makes radical changes.

What are you? Now we know. What are you called? I think the term rational soul does just fine. Don’t you?