The commentary that follows was written by Darrel Falk.
I am asked all the time to explain, in a nutshell, why irreducible complexity is not a valid argument in favor of intelligent design. Indeed I have addressed this issue in Part I and Part II of this series. However, I have never heard anyone put it in a more cogent form than Oxford biophysicist Ard Louis in this video. If you are like me though, you’re going to have to listen extremely closely and probably play it two or three times in order to fully grasp the depth of the point he is making. Here is what I think he’s saying. Tell me if I’m right.
Dr. Louis begins by pointing out the complexity of the bacterial flagellum—it consists of many different protein components that must assemble in a specific configuration, a process which takes about twenty minutes. As the components assemble, they might try out many different arrangements until at long last the correct one is identified, producing a fully mature bacterial flagellum.
The problem is that there are a “zillion” different possible combinations and configurations of the components and only one works. Trying them all out and arriving at the single correct one in just twenty minutes would be impossible. Yet, the flagellum assembles. It works. And it works in twenty minutes. Dr. Louis goes on: If you were to come across a fully assembled flagellum with all of its protein components attached in the one and only way which works, what might you conclude? Remember there are zillions of ways in which those proteins could assemble, but in the search process, only one works. Given the state of our knowledge until recently, you might well conclude that there was a “guiding hand” or a “vital force” that had facilitated the assembly process enabling it to find the correct combination in only minutes.
Yet none of us, I assume, believe that there is a guiding hand acting on the cell, causing the proteins inside it to follow the correct search process to make the flagellum. The basic elements of the process are understood, Louis says. They can be explained both mathematically and biologically. We do not need to invoke a guiding hand inside each of the trillions of bacterial cells that are in our body. Their parts, including their flagella, are assembled by processes that we have come to understand over the past half century. No vital force. No guiding hand.
Louis then goes on to explore another aspect of the assembly of the bacterial flagellum: the evolutionary history by which it arose to become the complex structure it is today. That search process took place not in twenty minutes, but over millions of years—probably hundreds of millions. We don’t have the intermediates for this evolutionary history. All we have is the final product. Today, there are people who look at that structure in all of its complexity and say, “There must have been a guiding hand, a vital force to design and build something so complex. Even with hundreds of millions of years of searching in design-space, no natural process could build something this complex.” So, just as some were incredulous that a flagellum could self-assemble in a cell before our current state of knowledge developed, leaders of the Intelligent Design movement are now incredulous in a new way. For what they consider to be scientific reasons, they believe it is nearly certain that the structure must have come fully formed through an intelligence and not have become increasingly more complex through gradual, natural processes.
Louis, a deeply committed Christian, says in essence, “Given our incomplete knowledge about these processes, how do they know that?” True, showing how the flagellum could have been produced by natural processes is a hard problem—we don’t, after all, have the intermediates. However, is it not too early to say that scientists are never going to discover a natural way in which this could come about? Surely we cannot calculate probabilities of this, when we know so little about the process. Is it not premature to come across a finished product and say there must have been a guiding hand when we know so little about the history of its development over hundreds of millions of years?
Again, I emphasize that Dr. Ard Louis is a deeply committed Christian, a person who sees the Bible as the Word of God. He is not arguing against the existence of a Creator. It is science he is discussing, not theology. There are no scientific reasons to say that a guiding hand was needed in evolutionary history to assemble what we now see as a marvelously complex structure. There are also no sound theological reasons to assert that God could not have used natural processes to carry out God’s creation command. God could have used natural processes! We believe that God is Creator of life, that God “spoke” life into existence, and that God’s Presence sustains the created world in its current state.
Think back to Louis’s initial premise about what happens in twenty minutes. There are no scientific or theological reasons to insist on the presence of a guiding hand which manipulates the process so that the proteins attach in all the right ways to build the flagellum of a bacterial cell. By the same token, there are no scientific or theological reasons for assuming that a manipulating hand is needed step by step to build better and better flagella in evolutionary time. Instead, we are simply left with this:
In the beginning was the Word, and the Word was with God, and the Word was God. He was with God in the beginning. Through him all things were made; without him nothing was made that has been made. (John 1:1-3)
That is enough for me.
Commentary written by the BioLogos editorial team.