Repost: Intelligent Statistics
An accessible, and admittedly basic, introduction to the concept of natural selection can be read at Wikipedia:
The essential difference between natural selection and design detection as explanatory tools is one akin to the difference between scientific and mathematical truth.
Mathematics defines a triangle more or less as a closed figure with three straight sides (line segments). Nothing that anyone has ever held in her hand or viewed from afar (or closely) conforms to this definition in the real world. Nothing. A triangle's sides are perfectly straight and are one-dimensional. The usefulness of the strict definitions of mathematics are derived by the benefits they provide in further deduction, not at all by any one-to-one clarity they provide in regard to the real world.
Science is different. The twin rovers Spirit and Opportunity, which were so successful on Mars, each carried a thermal emission spectrometer (TES [or, rather, mini-TES]). These devices (tests, really) operate on the empirical reality that rocks of different material composition reflect thermal infrared light differently, making it possible to identify different materials in matter by looking at the thermal infrared signatures. This was the way scientists hoped to identify the mineral hematite on the surface (or below the surface) of Mars, which would, in turn, lend credibility to the existence—past or present—of water on the planet. The constructed test was based on real-world observations, and the hopefulness behind its potential was, in part, based on the idea that Mars and Earth are both subject to the same physical laws.
Design detection is a construct that has no empirical inputs that would give us confidence that what was tested for was indeed what we were looking for. If by some impossibility we actually detected something in the real world that conformed perfectly to a strict definition of a triangle, we would have no reason to claim that our test works at finding "real" triangles. The only evidence we would have that we found a triangle would be the test itself. Intelligent design may well indeed find design 100% of the time. But we would have no objective reason to believe this is true, because the only evidence for the findings would be the test itself.
Design detection proposes an unreality--and I don't think intelligent design theorists would object to this description--that specified events of extremely small probability must have a designed causality. It is not an "unreality" because it is not objectively true; it is such because it is not derived from any reality.
As scientific truth, well, it simply isn't. As a kind of philosophical/mathematical truth, intelligent design has yet to show its usefulness.
It doesn't take a great deal of gumption to admit that natural selection is, as envisioned by those who work with the theory, an "undirected process." But "undirected process" cannot reasonably be read as equivalent to "total randomness," so the oft-implied claim that intelligent design proposes a kind of common-sense alternative to the wacky idea of speciation and adaptation as being slapped together by an unbelievable coincidence of cosmic chance is, at the very least, disingenuous. Indeed, there is a fair amount of assumed regularity in what has been proposed as the mechanism of natural selection—this, in part, leads some to question, with good reason, whether regularity, chance, and design really are mutually exclusive explanations for events.The basic concept of natural selection is that the physical and biological environment ("nature") selects those variant traits of individual organisms that contribute better to the survival and reproduction of their carriers: Individuals carrying unfavorable variants might die before reproducing and/or produce fewer or lower-quality progeny, while individuals carrying favorable variants are more likely to survive until reproduction and/or to produce more and/or higher-quality progeny.
The essential difference between natural selection and design detection as explanatory tools is one akin to the difference between scientific and mathematical truth.
Mathematics defines a triangle more or less as a closed figure with three straight sides (line segments). Nothing that anyone has ever held in her hand or viewed from afar (or closely) conforms to this definition in the real world. Nothing. A triangle's sides are perfectly straight and are one-dimensional. The usefulness of the strict definitions of mathematics are derived by the benefits they provide in further deduction, not at all by any one-to-one clarity they provide in regard to the real world.
Science is different. The twin rovers Spirit and Opportunity, which were so successful on Mars, each carried a thermal emission spectrometer (TES [or, rather, mini-TES]). These devices (tests, really) operate on the empirical reality that rocks of different material composition reflect thermal infrared light differently, making it possible to identify different materials in matter by looking at the thermal infrared signatures. This was the way scientists hoped to identify the mineral hematite on the surface (or below the surface) of Mars, which would, in turn, lend credibility to the existence—past or present—of water on the planet. The constructed test was based on real-world observations, and the hopefulness behind its potential was, in part, based on the idea that Mars and Earth are both subject to the same physical laws.
Design detection is a construct that has no empirical inputs that would give us confidence that what was tested for was indeed what we were looking for. If by some impossibility we actually detected something in the real world that conformed perfectly to a strict definition of a triangle, we would have no reason to claim that our test works at finding "real" triangles. The only evidence we would have that we found a triangle would be the test itself. Intelligent design may well indeed find design 100% of the time. But we would have no objective reason to believe this is true, because the only evidence for the findings would be the test itself.
Design detection proposes an unreality--and I don't think intelligent design theorists would object to this description--that specified events of extremely small probability must have a designed causality. It is not an "unreality" because it is not objectively true; it is such because it is not derived from any reality.
As scientific truth, well, it simply isn't. As a kind of philosophical/mathematical truth, intelligent design has yet to show its usefulness.