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Talk:Falsifiability of evolution (view source)
Revision as of 12:56, June 7, 2008
, 12:56, June 7, 2008→Edit summary
: I've heard various proposals on how evolution could be falsified, but none so far seem convincing to me. I therefore think that the only proposed falsifications that should be included in the article are those made by professional or widely-accepted evolutionists. The first three are from TalkOrigins, so they can stand (pointing out their flaws), but the fourth, unsourced, I will remove.
: I've heard various proposals on how evolution could be falsified, but none so far seem convincing to me. I therefore think that the only proposed falsifications that should be included in the article are those made by professional or widely-accepted evolutionists. The first three are from TalkOrigins, so they can stand (pointing out their flaws), but the fourth, unsourced, I will remove.
: [[User:Philip J. Rayment|Philip J. Rayment]] 23:33, 5 June 2008 (EDT)
: [[User:Philip J. Rayment|Philip J. Rayment]] 23:33, 5 June 2008 (EDT)
Hi Philip, I'll try to address your concerns as best I can here:
I think a great deal of the problem is a lack of distinction between three concepts: evolution, natural selection and common origin. While all three support each other, they're separate concepts that are all being lumped together and referred to as evolution.
The Merriam Webster's applicable definition of evolution is as follows (the other definitions are unrelated to biology):
4 a: the historical development of a biological group (as a race or species) : phylogeny b: a theory that the various types of animals and plants have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations; also : the process described by this theory
Essentially, this is in line with the first definition of evolution, and essentially regarded as fact by most scientists.
Natural selection is a proposed mechanism by which evolution may occur. I'm pretty sure you're more than familiar with it, so I won't bother detailing it, but the important distinction is that disproving natural selection does not mean disproving evolution. The other important point on natural selection is that modern evolutionary theory has itself evolved and only considers natural selection one of many forces driving evolution. For instance, the discovery of horizontal gene transfer revealed that DNA can actually be exchanged between different organisms coming into contact with each other. There are a host of factors at play beyond natural selection and variation by mutation, so this aspect of the definition is somewhat misleading.
The theory of common descent of course is the theory that all living organisms descend from a common ancestor, which is the point the second definition speaks to. It's important to realize that this is not the same thing as the most primitive form of life or the first living organism. In fact, research supports the theory that our common ancestor was not a "protocell" or even a single celled being, but a primitive multicellular organism: [http://www.pnas.org/cgi/content/full/95/12/6854]
However, common descent is not necessary for evolution to hold, and the opposite is true as well; it's hypothetically possible for the descendants of a single ancestor to be wildly different for reasons unrelated to evolution. After all, if you're a creationist, you must believe in the possibility of divine intervention. Transformationism is the idea that organisms can evolve, but have evolved from multiple ancestors instead of a common one.
* The test of falsifiability is simply whether a theory could POTENTIALLY be falsified based on a test of its predictions. If it IS falsified, the next step is to adjust the theory to account for the discrepancies. Theories are not static, unchanging things, but working models that are adjusted to account for observation. That being said, the argument about wheels and magnets is essentially an older version of the doctrine of intelligent design; namely that the discovery of biological structures with no possible evolutionary path would invalidate evolution. The discovery of wheels and magnets in nature has nothing to do with evolution unless we're talking about wheels and magnets in biological structures, and even then, only if no reason could be found that a less evolved structure could be advantageous. The existence of wheels and magnets alone, even in a biological structure would NOT be a test of evolution. Unfortunately the current treatment of Haldane's quote lacks the context to make this distinction.
* All the proposed tests are logically possible, but not necessarily logistically. This isn't a strike against the theory though because falsifiability only requires that the theory be CAPABLE of being tested, not necessarily testable with our current technology. Testing the theory of relativity requires either the technology to accelerate matter to fantastic speeds and incredibly accurate clocks. Had we not invented particle accelerators or atomic clocks, it's likely we still would not have tested Einstein's theories. That being said, the lack of this technology would not have affected the falsifiability of relativity. Testable predictions do NOT need to distinguish between the hypothesis and competing ideas. The example of gravity in this article is a perfect example of this. The theory of gravitation predicts the rate at which an apple will fall from a tree (possibly injuring any physicists sitting beneath it) and because this can be tested the theory is falsifiable. However, it does not rule out the possibility that said apple falls to the ground for reason other than gravity. The discovery that mutations can't accumulate is actually would falsify evolution wholesale, and so it's a legitimate test, just as testing whether apples don't fall. The fact that the results of the test do not falsify the theory is irrelevant. If the question is whether the overarching theory of evolution can potentially be falsified, testing whether mutations can accumulate within a species is a valid test, not just hand waving.
* The platypus is a monotreme like the echidnas (which also lay eggs.) While its bill superficially resembles that of a bird, it's actually an elongated pliable snout with covered in sensitive skin. Its spines are poisonous, but the venom is chemically unlike that of snakes and reptiles, or any other animal for that matter. A true chimera would incorporate elements that were structurally, not just superficially, identical. Similarity is not enough to qualify as a chimera, and not all chimeras would falsify evolution. The lineage of monotremes diverges from that of other mammals from a point far in prehistory when mammals first began to evolve from reptiles, explaining why they share characteristics with them (i.e. laying eggs.) The discovery of a chimera composed of elements from organisms whose phylogeny is widely divergent would thereby disprove evolution.
* Direct observation: If we observed new organisms being created that did not inherit characteristics of their progenitors, clearly evolution would be disproven.
* Dissimilar DNA: if an organism was shown to be less similar to a phylogenetically close organism than a phylogenetically distant one, evolution would be disproved. Example: if humans were found to be more similar genetically to chickens than apes.
If you read Whitten's quote carefully, you'll not he speaks about challenging "the robustness of a prevailing worldview like evolution" and not about evolution per se. The article is about the institutional bias against challenging established viewpoints. In his original quote, you note that he states "they may happen to stumble across facts which would seem to conflict with its predictions." If it's even possible to test these predictions, clearly evolution is falsifiable! [[User:Xyrophile|Xyrophile]] 08:56, 7 June 2008 (EDT)