September 02, 2005

Misuse of scientific arguments

When I was in my first or second year of college, a friend of mine who belonged to a fundamentalist Christian church in Sri Lanka said that he had heard of a convincing scientific proof against the theory of evolution. He said the proof centered on the concept of entropy. I had already heard of the term entropy at that time, but I definitely did not understand the concept, since I had not as yet studied thermodynamics in any detail.

Anyway, my friend told me that there was this law of physics that said that the total entropy of a system had to always increase. He also said that the entropy of a system was inversely related to the amount of the order and complexity in the system, so that the greater the order, the lower the entropy. Since I did not have any reason (or desire) to challenge my friend, I accepted those premises.

Then came the killer conclusion. Since it was manifestly clear that the theory of evolution implied increasing order (under the theory, biological systems were becoming more diversified, complex, and organized from their highly disordered primeval soup beginnings) this implied that the entropy of the Earth must be decreasing. This violated the law of increasing entropy. Hence evolution must be false.

It was a pretty good argument, I thought at that time. But in a year or two, as I learned more about entropy, that argument fell apart. The catch is that the law of increasing entropy (also known as the second law of thermodynamics) applies to closed, isolated systems only, i.e., systems that have no interaction with any other system. The only really isolated system we have is the entire universe and the law is believed to apply strictly to it.

For any other system, we have to make sure that it is isolated (at least to a good approximation) before we apply the law to it, and this is where my friend's argument breaks down. The Earth is definitely not a closed system. It continuously absorbs and radiates energy. It especially gains energy from the Sun and radiates energy into empty space and it is this exchange of energy that is the engine of biological growth.

So nothing can be inferred from the entropy of the Earth alone. You have to consider the entire system of the Sun, the Earth, and the rest of the universe, and you find that this leads to a net increase of the entire closed system. So the second law of thermodynamics is not violated.

You can have decreased entropy in a part of a system provided the entropy increases by more than that amount in another part. As an analogy, consider a sock drawer in which you have black and brown socks randomly mixed together. This is a state of low order and hence high entropy. If I now sort the socks so that all the black socks are on one side of the drawer and all the brown on the other side, then the sock drawer has gone from a lower to a higher state of order, and hence from higher to a lower state of entropy. Is this a violation of the second law? No, because it ignores the fact that I was part of the system. I had to use up energy to sort the socks, and in that process my entropy increased more than the decrease in entropy of the sock drawer, so that there was a net increase in entropy of the combined system (sock drawer + me). Strictly speaking, I was also in contact with the rest of the room since I was absorbing and radiating energy, breathing, etc., so if you wanted to get to an even better approximation to a closed system to be even more accurate, you had to take the entropy of the room into account as well.

This is why physicists believe that after the Sun eventually burns up all its nuclear fuel and ceases to exist, the Earth will inevitably fall into disorder, assuming that we haven't destroyed the planet ourselves by then. (As an aside, Robert T Pennock in his book Tower of Babel says that some creationists believe that God created the second law, with its increasing disorder, as part of his punishment for Adam and Eve's fall from grace.)

Once I understood better what entropy was all about, that was the end of the entropy argument against evolution, at least as far as I was concerned. Non-physicist scientists generally caught on to the fact that people were using the entropy argument fraudulently against evolution and were able to debunk it whenever it came up, so that nowadays one rarely hears that argument. One still occasionally comes across the entropy argument used in this fallacious manner, however, and it may still have power over the scientifically naive.

But even if the entropy argument itself has largely disappeared, other 'scientific proofs' against evolution and for the existence of god have arisen in the wake of so-called intelligent design (ID) and I will look at those arguments in future postings.


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Tracked: September 8, 2005 08:06 AM


Hear hear!


Posted by Ben on September 2, 2005 05:03 PM

this reminds me of an argument i once heared about I.D. The individual said that certain biological systems were so complex that the only way they could have come into existance was by a desighner. The example that this individual used was the mammilian eye.

I thought about this for a long time, and, after studying biology and physiology at case, have come to the conclusion that if there is a desighner, then he certainly isn't intelligent. The mammilian eye, to use the mans argument, is completely ackwards. The photoreceptors that detect light are all the way in the back of the eye, and light has to go through multiple cell layers in order to be detected. Why would a god have created such a backwards system? he would have never passed his case BME classes with a design like that! The argument just doesn't hold.

Posted by Brooke on September 2, 2005 05:13 PM

After their stinging losses in the courts during the 70s and 80s the paleo-creationists or the YECs have put up a list of arguments that should not be used against evolution! and the law of entropy is one of them! The neo-creos or the ID proponents have polished up their arguments and now instead of entropy use the terms "information", "design", "comlexity", "specification" and "intelligence". All these have popular meanings vastly out of proportion to their scientific usage. This helps to mislead and confuse even well-informed people. And this serves the ID'rs very well in public "debates". On one side is the scientist marshalling tomes evidence and interpretation, on the other is the pseudoscientist who casually tosses out statements such as "increase in complexity cannot be achieved without intelligent input". Unless the terms concerned are defined such a statement is meaningless. But the audience is easily mislead as it immediately connects these statements with its commonsensical understanding. Result - the IDr wins the "debate".

Posted by shiva on September 2, 2005 08:36 PM


You might be interested in Richard Dawkins' book Climbing Mount Improbable where he tackles this question of how seemingly complex systems can arise from natural selection.

Posted by Mano Singham on September 3, 2005 11:02 AM


Could you please give me the link to the site where they creationists list the arguments that they recommend not being used? Thanks!

Also, I will be having a series of postings talking about the differing arguments posed by creationists and suggestions for how they might be combated.

Posted by Mano Singham on September 3, 2005 11:05 AM


I am mistaken about the retraction of the 2nd Law argument. But there are a whole lot of other arguments that creos are advised not to use that can be found here

Creos continue to spin the 2nd Law argument as here

The paleo creo arguments have all but been blown out of the water. The debate these days is around neo-creo or ID. The ID'rs are more subtle and are slick and extremely devious. (a weblog) is an excellent source of information on ID, as is

Posted by shiva on September 3, 2005 11:27 AM

Hi Mano,

Just had a quick look at your blog. Will go through some of your postings at leisure.

Your blog seems to be quite popular as I got 735 hits when I searched Google with the key words' blog+ mano singham'. In fact I thought I may not even reach your blog with these key words.

Finally for now, I prefer 'Agnostic' to 'Atheist' and not because it may cause any serious ripples in the listener, but because I feel I do not really know. I must admit though that I have not referred to the Oxford dictionary defnitions to decide which word is closer.

Someone once said an agnostic is one who desperately wants proof of a god. I think I fall into that category.

Posted by manik on September 5, 2005 02:24 AM

Mano, I've never thought of myself of super smart by any means. I realize I probably posses an intellect above that of an average American, but when I read the entropy argument I laughed out loud.

Understandably, if you don't know what entropy is, the argument seemingly makes sense. I guess I just took for granted something that I learned in high school and reinforced with a degree in physics.

I can only imagine how any professional scientist would feel hearing that in a debate. "Deer in headlights" comes to mind, not because they shouldn't know what entropy is, but because of the shock that a premise so laughably ridiculous was just brought up to refute evolution.

Posted by Barry on September 23, 2005 09:37 AM

I think we have sufficient questions which can't be answered by searching only scientific reasons. the first in my mind is , how can be an ATOM produced?. then how can be different ATOMS and then the whole universe?. Also How can one regularize the whole substance produed. The same questions are on the biological side as well. If we can't do these, then why not we admit that there is someone who produced it. INTELEGENT DESIGNER may be his one name.

Posted by Tayyab on October 26, 2005 01:00 AM

But Tayyab, why stop there? After all, we do not know the causes of cancer, MS, Lou Gehrig's Disease, Alzheimer's etc. Why not assume that the intelligent designer created all those diseases and stop research on finding causes and cures for them?

Posted by Mano Singham on October 26, 2005 09:30 AM

what would you say to the arguement that
entropy increases with the addition of heat, therefore either the entropy of the earth is increasing or it is getting colder. Since we have no reason to believe it is actually getting colder, the entropy must be increasing. And surely the life we now observe is more ordered than hot volcanic mud or whatever we think exsisted before life?

Posted by Paul on March 27, 2006 03:18 PM


The thing about the Earth is that it gains heat from the Sun and loses heat by radiating it away into the cold universe. So the Earth is a system that has heat flowing through it all the time, making simple entropy arguments hard to construct.

The realtionship of entropy to evolution has been looked at pretty exhaustively. A fairly short response can be found here and more comprehensive ones here.

Posted by Mano Singham on March 27, 2006 05:06 PM

If there is work or transfer of energy there is increase in entropy and entropy disorder to learn more visit

Posted by Saha on June 2, 2009 03:02 AM

Interesting discourse. Never heard of the concept of entropy.

Posted by Eujenio de la Garcia on July 10, 2009 07:38 AM


Destroying the plant is a very touchy subject. Many factors play into. Health, economics, religion, etc.
Entropy is concept that I never heard of.

Posted by Joseph on November 13, 2011 09:02 PM