The Failures of Mathematical Anti-Evolutionism
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The Failures of Mathematical Anti-Evolutionism (Jason Rosenhouse) (z-lib.org)
(Meyer 2013, 173)
This is a remarkable paragraph. One would have thought it obvious that mutation and selection both play a crucial role in the process of evolutionary innovation. According to evolutionary theory, complex, functional structures arise through the interplay of mutation and selection. It does not make sense to say that one or the other is the ultimate source of the adaptation. It is fine to say that mutation provides the ultimate source of variation, but it is flatly wrong to say it is the source of innovation. Continuing with the analogy of writers and editors, mutation is like a sloppy, self-indulgent writer who buries a few pages of insightful writing within hundreds of pages of unpublishable nonsense. The editor then plays a crucial role in the process by separating the few worthy pages from the mountains of chaff. Consider an analogy. Imagine a child learning to play chess. He plays many practice games with his coach, who dutifully critiques his moves and shows him better ways of playing. Years later the child becomes a master-strength player. Meyer’s argument is tantamount to saying that the coach played no role in the process of the student becoming a master. After all, the coach had nothing to critique until the child actually made some moves at the board. In the analogy, 5.5 the basic argument from improbability 131 mutation is like the child making moves and natural selection is like the coach passing judgment on them. And just as the child’s moves and the coach’s commentary were both essential to turning the child into a master, so too are mutation and selection both essential to the process of biological innovation. Summarizing, we have here another instance of evolution’s crit- ics failing to take into consideration the probabilistic and geometric structure of protein space. Specifically, the probability distribution appropriate to protein space is highly nonuniform, meaning that some proteins are far more likely to be found in organisms than others. And our movement through protein space is highly constrained by its geometric structure since each generation almost exclusively investigates points that are near to the generation before. The BAI ignores both of these points and can be dismissed for these reasons. There is also a third serious problem with the BAI: It treats low probability, all by itself, as a refutation of evolution and confirmation of design. The problem with this approach is that extremely improba- ble events happen all the time. We have previously mentioned the old saying that million to one odds happen eight times a day in New York City. The biological analog is this: The course of evolution is affected by so many chance events that any specific modern outcome of the process could be extremely low, but this does not make us suspect design, because something had to happen. Therefore, some additional argument is needed to go from low probability to a conclusion of design. We need to argue not simply that, starting from the origin of life, a given protein was unlikely to have evolved, but also that this is the sort of improbability that needs a special explanation. Proponents of the BAI do not supply that additional argument. The BAI has the great virtue of computational tractability. By reducing probability to combinatorics, its proponents are able to carry out actual calculations to produce the desired small numbers. However, we have seen that the mathematical model on which the BAI relies is far too unrealistic to produce meaningful results. Evolution does not proceed by randomly selecting complex structures 132 5 probability theory from spaces of equiprobable possibilities, but instead builds them gradually by accumulating many small changes, a process we can refer to as “cumulative selection.” Including a role for cumulative selection in the model would make it all but impossible to carry out meaningful calculations. The number of variables influencing the probabilistic structure of protein space is enormous. It is effectively impossible to identify them all, much less to assign appropriate numbers to them. Thus, anyone seeking to use probability theory to refute evolu- tion must deal seriously with these two questions: • How do we preserve the computational tractability of the BAI while working within a biologically reasonable model? • How do we justify the conclusion that evolution has been refuted simply because a particular mathematical model tells us that an event of low probability has occurred? The remainder of this chapter will discuss the main attempts from ID proponents to circumvent these issues. As we shall see, they are not successful in doing so. 5.6 complex specified information If you spend much time reading ID literature, you will encounter the concept of “complex specified information (CSI).” In the form used by ID proponents, the concept is the brainchild of mathematician William Dembski. In his telling, CSI is an attribute that an event may or may not exhibit. We are using the term “event” very broadly to refer to any particular occurrence or object. He claims that when CSI is present, you can be certain that intelligent design is in some way involved in the causal history of the event. He writes: When trying to explain something, we employ three broad modes of explanation: necessity, chance and design. As a criterion for detecting design, specified complexity enables us to decide which of these modes of explanation apply. It does that by answering three questions about the thing we are trying to explain: Is it 5.6 complex specified information 133 contingent? Is it complex? Is it specified? By arranging these questions sequentially as decision nodes in a flowchart, we can represent specified complexity as a criterion for detecting design. Download 0.99 Mb. Do'stlaringiz bilan baham: |
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