Sunday, April 09, 2006
Irreducible Complexity: What it is and Popular Misconceptions
Many people seem confused about what Irreducible Complexity is. I've had to explain it to several people, and have tired of it, so I'm writing this post so that I can just refer people here :)
The basic definition is not much in dispute. It is this:
So, basically you have (a) well-matched parts, and (b) a core system.
Many people think that irreducible complexity is in and of itself an argument from ignorance. But actually it is an argument from what we know about how designers design, so it is an inference. Designers design systems holistically. Therefore, if we see something that is holistically design, we can infer that there was a designer somewhere behind it. The problem comes in defining "holistically designed" so that it can be measured. Irreducible Complexity is simply an attempt at an empirical definition of holistic design. It may or may not wind up being true (I have a hunch that it will be true, though like any concept in science the definition will likely have to be modified as it gets more discussion), but that is what it is in a nutshell.
Some simple misconceptions:
Behe's main (and controversial) claim regarding such systems is that Irreducibly Complex systems cannot be evolved by Darwinian processes. Many people mistakenly think that this means that Irreducibly Complex systems cannot have evolved at all. This is not the case. What it means is that in order for an IC system to evolve, it had to have done so more-or-less all-at-once. The reason that we often conflate this with being unable to evolve is that we often mistakenly consider Darwinian evolution to be the only kind. However, there are other kinds of informationally-driven evolution which are able to do just this sort of thing, which are often covered on this blog.
Here is a short blurb which very much sums up how the evolution of irreducible complexity works (though the term Irreducible Complexity is not used in the paper):
So, the existance of non-Darwinian mutational mechanisms which drive change into specific or semi-specific, beneficial directions is fully inline with Irreducible Complexity. However, one must then consider the origin of such non-Darwinian processes. My next post will cover that more. Until then, I leave you with these two links: Searching Large Spaces and Evolutionary Computation: A Perpetual Motion Machine for Design Information?. When reading them, think about how generating multiple sequence changes in a single step which bypass neutral or bad modifications is related to concepts such as a "structured search space".
Two things we can learn from Irreducible Complexity:
Next time I'll go into "Chance Favors the Prepared Genome" further, along with a few other things.
The basic definition is not much in dispute. It is this:
A single system which is composed of several interacting parts that contribute to the basic function, and where the removal of any one of the parts causes the system to effectively cease functioning.
So, basically you have (a) well-matched parts, and (b) a core system.
Many people think that irreducible complexity is in and of itself an argument from ignorance. But actually it is an argument from what we know about how designers design, so it is an inference. Designers design systems holistically. Therefore, if we see something that is holistically design, we can infer that there was a designer somewhere behind it. The problem comes in defining "holistically designed" so that it can be measured. Irreducible Complexity is simply an attempt at an empirical definition of holistic design. It may or may not wind up being true (I have a hunch that it will be true, though like any concept in science the definition will likely have to be modified as it gets more discussion), but that is what it is in a nutshell.
Some simple misconceptions:
- IC does not mean that the parts can't have redundancy -- it just means that a core system is essential. If there are two of them for redundancy or efficiency, the system itself is still just as essential as it would be otherwise.
- IC does not mean that there aren't individual components that might not be IC. If a system is IC, it really means that it has an IC _core_ to it.
- IC does not mean that the parts can't be used for something else. My radio circuit board consists of transistors, resistors, capacitors, and a speaker. The fact that speakers are used in other systems does not mean that a radio does not have an Irreducibly Complex core.
Behe's main (and controversial) claim regarding such systems is that Irreducibly Complex systems cannot be evolved by Darwinian processes. Many people mistakenly think that this means that Irreducibly Complex systems cannot have evolved at all. This is not the case. What it means is that in order for an IC system to evolve, it had to have done so more-or-less all-at-once. The reason that we often conflate this with being unable to evolve is that we often mistakenly consider Darwinian evolution to be the only kind. However, there are other kinds of informationally-driven evolution which are able to do just this sort of thing, which are often covered on this blog.
Here is a short blurb which very much sums up how the evolution of irreducible complexity works (though the term Irreducible Complexity is not used in the paper):
“A genome’s ability to grow and to explore new organizational structures would be severely constrained, if its options were limited to simple point mutation…most organisms tolerate only relatively low levels of point mutation in a gneeration. Instead they have evolved mechanisms that generate multiple sequence changes in a single step, allowing them to bypass unselected neutral, and negatively selected, sequences that may lie on point mutation pathways between the current sequence and a more optimal sequence. Indeed, where genomic sequences have been available to provide a window into the evolution of a new gene, the series of steps revealed has been complex.” [from Chance Favors the Prepared Genome, emphasis mine]
So, the existance of non-Darwinian mutational mechanisms which drive change into specific or semi-specific, beneficial directions is fully inline with Irreducible Complexity. However, one must then consider the origin of such non-Darwinian processes. My next post will cover that more. Until then, I leave you with these two links: Searching Large Spaces and Evolutionary Computation: A Perpetual Motion Machine for Design Information?. When reading them, think about how generating multiple sequence changes in a single step which bypass neutral or bad modifications is related to concepts such as a "structured search space".
Two things we can learn from Irreducible Complexity:
- Look for holism in nature. This is the impetus of Jonathan Well's foray into centriole mechanics. I'm sure there's numerous other research projects down this path.
- Try to find empirical definitions for intuitive concepts. Creationists often rely on intuitive concepts that we have trouble expressing to the empirical crowd. IC as an empirical definition of holism might be an example to follow on how to formulate such concepts.
Next time I'll go into "Chance Favors the Prepared Genome" further, along with a few other things.
Permanent Link posted by crevo @ 6:17 AM 
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"The basic definition is not much in dispute. It is this:
A single system which is composed of several interacting parts that contribute to the basic function, and where the removal of any one of the parts causes the system to effectively cease functioning."
Ok - what is a "single system"? How do we determine system boundaries? How do determine the basic function? Is it necessarily the one that appears most obvious?
"So, basically you have (a) well-matched parts, and (b) a core system."
This paragraph is unclear. What is a "core system"? How does it differ from a "single system"?
"IC does not mean that the parts can't have redundancy -- it just means that a core system is essential. If there are two of them for redundancy or efficiency, the system itself is still just as essential as it would be otherwise."
Ok, the parts can have redundancy - there can be more than one of each. Compare that to the definition:
"the removal of any one of the parts causes the system to effectively cease functioning"
The definition does not allow for redundancy. But the core system is IC. This would indicate that the "core system" is the "single system" stripped for redundancies.
But this still means that we cannot count both a system with redundancies and a system without redundancies as equally necessarily designed; because then anything is designed.
Compare with this little snippet from William Dembski's article Is Intelligent Design Testable?:
"one can determine whether a system is irreducibly complex without knowing the precise role that each part in the system plays (one need only knock out individual parts and see if function is preserved; knowing what exactly the individual parts do is not necessary)."
According to this snippet, we do not know what an individual part does to determine IC; therefore redundancy cannot be part of IC., since to determine if there is redundancy we need to know, what a part does.
Of course, we can knock out part A and see that the system keeps functioning, but that it ceases functioning, if we additionally knock out part B. If we then start with another copy of the system and knock out part B, and the system keeps functioning, but it ceases to do so, if we additionally knock out part A, we may say that A and B are mutually redundant. But this still means that the system is not IC - it might have been, if either A or B were missing, but they aren't (until we come knocking things out).
"IC does not mean that the parts can't be used for something else. My radio circuit board consists of transistors, resistors, capacitors, and a speaker. The fact that speakers are used in other systems does not mean that a radio does not have an Irreducibly Complex core."
Umm, if a part can be used elsewhere, it might as well have come from elsewhere, right?
"Behe's main (and controversial) claim regarding such systems is that Irreducibly Complex systems cannot be evolved by Darwinian processes. Many people mistakenly think that this means that Irreducibly Complex systems cannot have evolved at all. This is not the case. What it means is that in order for an IC system to evolve, it had to have done so more-or-less all-at-once."
Why? According to the above, parts could have come from elsewhere, some parts might have been redundant and possibly later changed to work differently. Also consider the possibility that the "basic function" of the system might have changed.
"The reason that we often conflate this with being unable to evolve is that we often mistakenly consider Darwinian evolution to be the only kind. However, there are other kinds of informationally-driven evolution which are able to do just this sort of thing, which are often covered on this blog."
Isn't Darwinian evolution "informationally-driven"? Natural selection informs a population about the rules around town, and the population had better adapt to those rules.
But ok, please do specify those alternative kinds of evolution.
A single system which is composed of several interacting parts that contribute to the basic function, and where the removal of any one of the parts causes the system to effectively cease functioning."
Ok - what is a "single system"? How do we determine system boundaries? How do determine the basic function? Is it necessarily the one that appears most obvious?
"So, basically you have (a) well-matched parts, and (b) a core system."
This paragraph is unclear. What is a "core system"? How does it differ from a "single system"?
"IC does not mean that the parts can't have redundancy -- it just means that a core system is essential. If there are two of them for redundancy or efficiency, the system itself is still just as essential as it would be otherwise."
Ok, the parts can have redundancy - there can be more than one of each. Compare that to the definition:
"the removal of any one of the parts causes the system to effectively cease functioning"
The definition does not allow for redundancy. But the core system is IC. This would indicate that the "core system" is the "single system" stripped for redundancies.
But this still means that we cannot count both a system with redundancies and a system without redundancies as equally necessarily designed; because then anything is designed.
Compare with this little snippet from William Dembski's article Is Intelligent Design Testable?:
"one can determine whether a system is irreducibly complex without knowing the precise role that each part in the system plays (one need only knock out individual parts and see if function is preserved; knowing what exactly the individual parts do is not necessary)."
According to this snippet, we do not know what an individual part does to determine IC; therefore redundancy cannot be part of IC., since to determine if there is redundancy we need to know, what a part does.
Of course, we can knock out part A and see that the system keeps functioning, but that it ceases functioning, if we additionally knock out part B. If we then start with another copy of the system and knock out part B, and the system keeps functioning, but it ceases to do so, if we additionally knock out part A, we may say that A and B are mutually redundant. But this still means that the system is not IC - it might have been, if either A or B were missing, but they aren't (until we come knocking things out).
"IC does not mean that the parts can't be used for something else. My radio circuit board consists of transistors, resistors, capacitors, and a speaker. The fact that speakers are used in other systems does not mean that a radio does not have an Irreducibly Complex core."
Umm, if a part can be used elsewhere, it might as well have come from elsewhere, right?
"Behe's main (and controversial) claim regarding such systems is that Irreducibly Complex systems cannot be evolved by Darwinian processes. Many people mistakenly think that this means that Irreducibly Complex systems cannot have evolved at all. This is not the case. What it means is that in order for an IC system to evolve, it had to have done so more-or-less all-at-once."
Why? According to the above, parts could have come from elsewhere, some parts might have been redundant and possibly later changed to work differently. Also consider the possibility that the "basic function" of the system might have changed.
"The reason that we often conflate this with being unable to evolve is that we often mistakenly consider Darwinian evolution to be the only kind. However, there are other kinds of informationally-driven evolution which are able to do just this sort of thing, which are often covered on this blog."
Isn't Darwinian evolution "informationally-driven"? Natural selection informs a population about the rules around town, and the population had better adapt to those rules.
But ok, please do specify those alternative kinds of evolution.
I agree more-or-less with your nitpicks, but think that they are only that -- nitpicks. What is failed to be addressed is the presence of holistic design, where many parts are engineered together for a single function.
One can argue that such a thing does or does not exist, and that Behe is or is not correct in either his definition or in the existence of IC. But what you and most others fail to address is what I consider to be the core issue -- the holistic appearance of these systems. While many evolutionists have argued for the origin of one thing or another, no evolutionist I am aware of is able to account for the holistic nature of numerous biological systems. I actually currently think that IC is a useful definition (though it may need to be modified slightly) but I think more importantly is that the main phenomena has yet to be explained.
"Isn't Darwinian evolution "informationally-driven"? Natural selection informs a population about the rules around town, and the population had better adapt to those rules."
Not really. Natural selection can inform what the laws are, but what causes the organisms to _change_ to keep the laws? Random mutation is not a sufficient answer because the search space is much too large. Information about _how_ to change in response to environmental stresses is needed.
I'll try to respond more later. Gotta get to work.
One can argue that such a thing does or does not exist, and that Behe is or is not correct in either his definition or in the existence of IC. But what you and most others fail to address is what I consider to be the core issue -- the holistic appearance of these systems. While many evolutionists have argued for the origin of one thing or another, no evolutionist I am aware of is able to account for the holistic nature of numerous biological systems. I actually currently think that IC is a useful definition (though it may need to be modified slightly) but I think more importantly is that the main phenomena has yet to be explained.
"Isn't Darwinian evolution "informationally-driven"? Natural selection informs a population about the rules around town, and the population had better adapt to those rules."
Not really. Natural selection can inform what the laws are, but what causes the organisms to _change_ to keep the laws? Random mutation is not a sufficient answer because the search space is much too large. Information about _how_ to change in response to environmental stresses is needed.
I'll try to respond more later. Gotta get to work.
Thanks for your response.
"I agree more-or-less with your nitpicks, but think that they are only that -- nitpicks. What is failed to be addressed is the presence of holistic design, where many parts are engineered together for a single function."
One might say that irreducible complexity is nitpicking as well, but I'll digress on that :-)
As for "the presence of holistic design", how whole is the holism? Behe and Dembski focus on the bacterial flagellum. In E. coli, iirc, the flagellum is made up of around 30 proteins with an additional 20 to assist in the assembly. A total of around 50 proteins out of 4,289; that is, slightly more than 1% of the proteins. How holistic is an argument that focuses on only 1%?
"While many evolutionists have argued for the origin of one thing or another, no evolutionist I am aware of is able to account for the holistic nature of numerous biological systems. I actually currently think that IC is a useful definition (though it may need to be modified slightly) but I think more importantly is that the main phenomena has yet to be explained."
I agree that you have a point here, and for some time I have been considered asking some evolutionists about, if there isn't really a problem here. Darwinian evolution strictly speaking only covers continous character traits - those that fit a gradualistic evolution model. Some characteristics don't really fit into that model. In particular when we move down to the molecular level. Here gradualism hardly makes sense.
So, yes, I agree that there is a problem, but I am not sure about, where to search for the solution.
"Not really. Natural selection can inform what the laws are, but what causes the organisms to _change_ to keep the laws? Random mutation is not a sufficient answer because the search space is much too large. Information about _how_ to change in response to environmental stresses is needed."
Goos point! One thing is to know that you have to change, another thing is to lnow how to change. But then again, species do become extinct, don't they? It's claimed that more than 99% of the species that have ever lived are extinct - although I'm not sure how reliable such a number is.
How does a species - or more precisely, a population - adapt? Well, that's the question.
"I'll try to respond more later. Gotta get to work."
I'll be looking forward :-)
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"I agree more-or-less with your nitpicks, but think that they are only that -- nitpicks. What is failed to be addressed is the presence of holistic design, where many parts are engineered together for a single function."
One might say that irreducible complexity is nitpicking as well, but I'll digress on that :-)
As for "the presence of holistic design", how whole is the holism? Behe and Dembski focus on the bacterial flagellum. In E. coli, iirc, the flagellum is made up of around 30 proteins with an additional 20 to assist in the assembly. A total of around 50 proteins out of 4,289; that is, slightly more than 1% of the proteins. How holistic is an argument that focuses on only 1%?
"While many evolutionists have argued for the origin of one thing or another, no evolutionist I am aware of is able to account for the holistic nature of numerous biological systems. I actually currently think that IC is a useful definition (though it may need to be modified slightly) but I think more importantly is that the main phenomena has yet to be explained."
I agree that you have a point here, and for some time I have been considered asking some evolutionists about, if there isn't really a problem here. Darwinian evolution strictly speaking only covers continous character traits - those that fit a gradualistic evolution model. Some characteristics don't really fit into that model. In particular when we move down to the molecular level. Here gradualism hardly makes sense.
So, yes, I agree that there is a problem, but I am not sure about, where to search for the solution.
"Not really. Natural selection can inform what the laws are, but what causes the organisms to _change_ to keep the laws? Random mutation is not a sufficient answer because the search space is much too large. Information about _how_ to change in response to environmental stresses is needed."
Goos point! One thing is to know that you have to change, another thing is to lnow how to change. But then again, species do become extinct, don't they? It's claimed that more than 99% of the species that have ever lived are extinct - although I'm not sure how reliable such a number is.
How does a species - or more precisely, a population - adapt? Well, that's the question.
"I'll try to respond more later. Gotta get to work."
I'll be looking forward :-)
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