Inference and its role in NS (General)

by dhw, Sunday, January 23, 2011, 19:02 (4862 days ago) @ xeno6696

MATT: I don't see this is rewording evolution; natural selection is the process that culls organisms that were unable to respond to some change..."Natural selection is the process by which traits become more or less common in a population due to consistent effects upon the survival or reproduction of their bearers." (Wikipedia) Traits becoming more or less common. In other words, evolution is natural selection. Without natural selection, we have no theory of evolution.-You can't have fish and chips without fish, but that doesn't mean that fish is fish and chips! All the phases of evolution, of which NS is one, are interlinked. Why, then, did you look for a definition of natural selection (not a problem) and not for one of evolution? Here is the Encarta definition: "the theoretical process by which all species develop from earlier forms of life." Longman: "the scientific idea that plants and animals develop and change gradually over a long period of time." Chambers: "the cumulative changes in the characteristics of living organisms or populations of organisms from generation to generation, resulting in the development of new types of organisms over long periods of time." What is common to all these definitions is development and change, and these are not PRODUCED by natural selection but by adaptation and innovation. NS only preserves these changes and developments.-MATT: It's in the language of biologists; an event that begins the process is called "selective pressure." While the organism is under pressure, it must find a way to adapt, behaviourally or molecularly. -If an organism is already perfectly adapted, it doesn't need to change. What you call "adapt molecularly" is the point at issue, because without that mechanism (plus the mechanism that produces innovations such as sex), there can be no evolution. What you have is therefore three stages, two of which speak for themselves: 1) if organisms don't adapt to the conditions they will die (selective pressure); 2) some organisms adapt/change/innovate; 3) those that have changed appropriately survive (natural selection). Phase 2 is the one that causes us all the problems.
 
MATT: Therefore, since no change happens without selective pressure, natural selection explains the whole of why organisms change.
 
"Selective pressure" explains why organisms NEED to change, and NS explains why certain organisms survive and others don't. Neither explains HOW organisms change. If the theory of evolution as defined above is true (I think it is, though "gradually" is a controversial description), we need to understand its physical mechanisms, which you seem to regard as somehow irrelevant. Evolution could not take place without them, and crucially for our discussions, it is their complexity (not the automatic process of NS) that underlies the dispute between theists and atheists, as I tried to explain in my post of 22 January at 10.21.