Punctuated equilibrium. An idea that arose from testing evolution. The original idea of constant but very slow change didn’t fit the fossil record and other observations, so the theory was altered in the face of evidence. Creationists love to use that as proof that scientists don’t know what they’re doing. To them, the answer is finite and known. In reality, we barely even know what the question is.
Of course ID is testable. It would predict, for example, that we have no appendix. That our optic nerves come out behind the retina as they do in octopuses. That the tube that delivers the semen would not pass twice through the abdominal muscle, thus opening us up for hernias. That our backs would stand up better to upright posture. That we would get replacement teeth. Not to mention fingers, arm, and legs. There are dozens, hundreds, maybe thousands of ways our design could be improved. But evolution works by continuous modification and we have our entire evolutionary history acting as a counterweight to such improvements.
As Doper said recently, it is foolish to argue with a fool; they have more practice.
You needn’t go drawing conclusions from their assertions to find something testable. You can simply take what they say at face value. You can test, for example, the age of the earth. You can test whether human ancestors exist. You can test whether there were ever any “waters” above “the firmament.”
Creationists love to make a lot of claims and then pretend like they haven’t. But they have. No need to bring retinas into it. Just test what they say. That’s enough.
Tangent, I suppose, but this is already a zombie and whatever. I get so frustrated when people claim that there’s a “theory of evolution” as distinct from the theory of evolution by natural selection. Evolution isn’t a theory, it’s an observation, or a fact. We observe it all the time, in drug-resistant bacteria and the like, as well as in the fossil record and myriad other places. Proposing that evolution does not occur is akin to proposing that gravity does not occur. It’s a denial of observations, and should be dismissed as such.
I think this matters, and that it’s not just splitting hairs. When anti-science folk attack evolution as an unproven theory, they are wrong about the very nature of the debate itself, and by failing to acknowledge this fact we continue to empower them. They’re not denying the arguments, they’re denying the facts. It’s not acceptable shorthand to write “the theory of evolution” in any context in which creationists are presently attempting to distort reality.
Like many scientific “facts” the occurrence of evolution was not a fact that many people noticed until after Darwin had provided them with an appropriate theoretical framework within which to understand the natural world. Even the handful of thinkers who argued in favor of some sort of evolutionary process before Darwin’s time were not aware of the truth of the “fact” that you are talking about.
Likewise with gravity. No-one knew of any “force of gravity” before Newton’s time. The word “gravity” just meant heaviness. The fact to be explained was not “gravity” but just that heavy things fall down (plus some facts about the movements of the planets, or, rather, theories about those motions derived by complex mathematical analyses of very precise measurements of their actual observable motions across the sky).
Likewise, the facts that Darwin and his contemporaries sought to explain were simply that there are lots and lots of different types of living animals and plants, apparently many more types that are no longer living, but can be found as fossils, and that these types are distributed around the globe in a particular (and sometimes rather puzzling) way. It took a remarkable degree of theoretical insight on Darwin’s (and, later, Wallace’s) part to recognize that these fact could best be explained in terms of a process of evolutionary differentiation. This was a much more revolutionary advance than the notion of natural selection as the main driver of evolution (which took him another couple of years to come up with).
In short, your distinction between facts and theories is naïve, and if there is a distinction to be drawn at all (which is questionable), you are drawing it in the wrong place. Evolution (even apart from natural selection) is a theory. It just happens to be one that is extremely well supported by the evidence, and whose truth can scarcely be doubted by any person who is not either deeply ignorant or intellectually dishonest (or both).
(And after he had that key insight, it took him a coouple mor years to come up with
This is basic scientific method stuff here. We have observations, which are alternatively called facts, or depending upon context, evidence. We use our knowledge of facts to create hypotheses, hypotheses to create predictions, predictions to create tests, and tests to create theories. Theories cannot really be true, but they can be ‘not yet known to be false.’ I assume that we’re all agreed on this. No naivete, just basic definitions.
Obscuring the difference between fact and theory is a major tool of the Creationists. They latch onto our admission that theories are incapable of being true and recolor the debate as one in which our basic observations are to be regarded skeptically. This is utter nonsense, and needs to be called out. We observe evolution in progress every day, and that is a true thing which needs to be stated in clear terms. We shouldn’t allow our definition of theory to be used as a weapon against facts.
It was well-enough observed for Lamarck to try to explain it, with a theory of his own – which was replaced by Darwin’s far superior theory.
I have to agree with twhitt: in formal scientific language, theories are never “proven.” They succeed by withstanding being demolished. The observed fact is that animals change form over time, including splitting into new species. Darwinian evolution explains how it happens, but it is an observed fact that it happens.
Creationists try to play up this distinction. twhitt is just noting that we shouldn’t give them that latitude.
Unfortunately “basic scientific method” (or what most people who think there is such a thing take it to be) is a very poor characterization of how science is actually done, especially conceptually innovative science, such as Darwin’s discovery of evolution by differentiation, and Newton’s discovery of gravity.
Unfortunately the difference between fact and theory is very obscure, as anyone who had spent more than half an hour or so seriously investigating the matter would know. A dumbed-down-to-the-point-of-being-false account of the nature of science and knowledge may make it easier to score points off creationists, but it will not persuade them (not that anything else will, I fear), and, ultimately, to insist on it is to renege on rationality in just the same sort of way that they do. Let’s fight lies with truths, not more lies (or even half-truths).
I am sorry but you are ignorant of the history of evolutionary theory. Lamark was not at all trying to explain the same the same “facts” as Darwin was, and although he believed (for reasons as much religious as observational) that organisms change over time, he most certainly did not believe that a species could split into different species. He believed that each species originated separately, from non-living matter, in a primitive form, and evolved over time to become steadily more complex. The main “facts” that he was trying to explain were the fact that some fossil forms of organisms seem to be quite different from any species around today, coupled with the “fact”, as he saw it, that a good and competent God would never create a species only to allow it to go extinct. His solution was that apparently extinct species were not extinct at all, but has simply evolved over time into a form that looks very different. He came up with the theory of inheritance of acquired characteristics in order to explain how this could happen, but that was secondary to his very unDarwinian conception of what evolution itself is.
The “fact” that new species arise by differentiation from older species was discovered, for the first time, by Darwin when he realized that this provided the only rational explanation for the otherwise incomprehensible way that different taxa were distributed in geographically isolated environments, such as remote ocean islands (many of which he had visited during his voyage on the Beagle). This distribution was not previously either a well known fact, and if any naturalists were aware of it they had not recognized it as being significant. In my opinion the concept of evolution by differentiation was Darwin’s most important and most brilliant discovery, considerably more so than the theory of natural selection that he later came up with to explain how the differentiation comes about. Certainly the discovery of natural selection depends upon the prior discovery of evolution by differentiation, and when, over 20 years later, Wallace independently came up with the idea of evolution by differentiation (after, like Darwin, having had much experience of exploring the biota of isolated islands) it did not take him long at all to come up with the natural selection mechanism to explain how it would work.
The history of science is full of instances like this of “facts” that seem obvious in hindsight, but that were actually very difficult to discover, because they require not new experiments and the proposing and testing of hypotheses, but a thoroughgoing reconceptualization of what is already “known”. One could almost say that the more obvious a new scientific concept comes to seem to subsequent generation, then the more difficult it must have been to discover in the first place. The reconceptualizations that constitute major scientific advances often highlight “facts” that had had previously seemed insignificant (like the fact that the Galapagos island have many species of finches, but no other land birds), and reveals others, previously thought highly significant, to be of little relevance, even if still widely accepted as true (such as God’s supposed goodness and competence). All, or almost all, of the people who are considered to be the great scientists of history (and many of the lesser ones too) were people who achieved such reconceptualizations, and then persuaded other people to see things their way. The method of hypothesize and test may often be valuable for filling out the details, once a conceptual framework is in place, but it is not how major advances in science happen. It can’t be, because what counts as a fact, and certainly what count as a significant fact, depends upon the conceptual framework of your thinking.
You probably need to be a bit more specific in what you mean by “evolution.” There are a number of typical candidates:
(1) Speciation by natural selection, id est, pressure is placed, deliberately or naturally, on a species, and over the course of many generations, a new specie evolves. This can be reasonably tested with bacteria, but on almost nothing else, because the required number of generations is too large. It cannot be tested on large animal species, because it requires of order 100,000 years or so. Still, if speciation can occur in microbes, who use the same DNA and general method of living, it’s very difficult to see how it can not occur in larger animals that breed slower. It’d be like observing you can lose money in a single day of trading on Wall Street – and then doubting that if you traded only every decade or so, you could still lose money. Kind of…odd. Still, just because humans (for example) could have developed from some primitive hominid ancestor, or a slime mold, given enough time, is not by itself proof that they did. (For example, it could be that the time required for a human to evolve from bacteria must be measured in trillions of years, not billions, and then we’d have a problem. Which brings us to…
(2) Statements of evolutionary relationships, e.g. the “Tree of Life,” such as the statement that humans and chimps are close relatives, and both evolved from a common ancestor 2 million years or so ago. Again, our experience with microfauna says this is possible, but that does not mean it necessarily happened. Our belief that it did is based on the fossil record – on comparing the body structures of modern humans, modern chimps, and fossilized members of both family, and seeing how the two branches diverge over the millenia. Tracing the divergence back, we arrive at a time period when the two branches were one. But we are, certainly, extrapolating, and the fossil record has many gaps and peculiarities. Other evidence comes from analysis of DNA, both nuclear and mitochondrial, but this is even more fraught with rafts of assumptions (about mutation rates, for example, and how they depend on the functionality of the DNA) and models built on a fairly rickety basis (for example, models that measure how “related” two dissimilar strands of DNA are). We really know too little about genomes to be super confident in this – and there are some famous cases where the fossil record and the DNA record do not appear to agree. It can all be rationalized, but…one can be forgiven for being not 100% sure of the current Tree of Life. Maybe some of the relationships in it are bogus, and maybe some others aren’t recognized. But can that include something as fundamental as humans are primates, like apes? Could it be that the rest of the animal world is related – but we stand outside? Seems…iffy.
(3) Abiogenesis. So life can evolve from other life, let’s say. But where does life come from in the first place? Here, all our ideas about evolution become very shaky indeed. We wave our hands and say, well, we can imagine an evolution of nonliving systems, too – mineral clays or small little micelles of lipids can evolve, under pressure, to become more suitable, which…er…I suppose might mean becoming more complex – really, incredibly more complex, until they turn into living cells. But this is really quite a lot of hand-waving. We have never seen anything at all like this in the laboratory – nobody has ever subjected chemical reactants, no matter how complicated, to natural pressure and observed a more complicated and “adaptive” (in any nontrivial sense of the word) system naturally emerge. And note that nonliving chemical systems would “evolve” much much faster than even the simplest bacteria, since they are responding on the timescale of chemical reactions – microseconds to milliseconds, typically. How is that generally speaking, we can directly observe evolution more and more easily, and on shorter time scales, the simpler the species – until we come to the simplest possible “pre-species” of all, which is nonliving systems, and there we’re stuck dead?
Of course, the obvious answer is, we have no idea what we’re doing. We don’t even know how to recognize nonliving system that are closer to, or further away from, living systems. We have a hard time even defining exactly what separates the boundary of living from nonliving (cue discussion of viruses and prions). So while we can construct plausible models for how finch beaks change in response to environment changes, or how moths become mottle, or E. coli become drug resistant, we have no models – zero – that explain how nonliving organic molecules become a living cell. It is a leap, a chasm, over which no one’s imagination has ever produced anything that is both sufficiently detailed and passes the laugh test.
It’s also a little weird that we have never ever observed even the slightest step towards abiogenesis other than 3.5 billion years ago – there is no evidence that it occurred more than once, or might be happening now. In fact, it has also so far as we can tell never happened on any other planet within a reasonable distance. We know there are no intelligence beings who use radio within 100 light years. If life can readily evolve from nonlife, it seems odd that it hasn’t anywhere else nearby, or else stopped with nonintelligent life. Of all the problems evolutionary biology must explain, that of the original origin of life is the thorniest, and one most amenable to criticism as being an act of faith not a whole lot less credulous than believing in divine creation.
Carl Pham, I would agree that abiogenesis is the flakiest part of evolutionary theory, if indeed it was a part of this theory. But it is not. We don’t need to make a claim about how the first species arose for the theory of natural selection to be validated, and to be useful.
It’s rather like how we can say that there is overwhelming support for the theory that the universe has/is expanding from a hotter, denser state, even as we shrug our shoulders about the first 10^-bajillion seconds, or indeed how/why its initial state was there in the first place.
There’s the problem right there: you’re confusing a legal definition of science, used for school funding decisions and school entry decisions, with a ‘scientific’* definition, which includes ideas like ‘testable’.
So you get questions which really mean “if it’s untestable, should it be in the same legal classification as ID”, which is not a scientific or philosophical question at all: it’s a legal question.
The difference is important, because there is no generally acceptable meaning of terms like “testable”. You can’t use one particular meaning in a different scientific or philosophical context, let alone a legal context.
Of course there is a historical/philosophical/anthropological/ question “to what extent are human systems of belief like science and Xtianity comparable? Are there any differences?”, but it’s important to realize that if you start that question from the Scopes trial, you’re starting from a position of irreconcilable confusion
*I put ‘scientific’ in quotes because few scientists do any study or research on philosophy, and their beliefs about science tend to be unscientific in the extreme.
Great Debates.
My understanding of the clay hypothesis that it says that clays could be places where organic molecules gather, increasing the chance that a molecule that can self-replicate would form. We know that self-replicating molecules are possible. The cell is not the first step in life, it is an advanced step in which the basic self-replicating molecules find themselves in a protective coating.
Bacteria have evolved to evolve. If self replicating molecules are subject to errors when replicating, which they are, that is all you need. I don’t know what the error rate is, and of course most errors would be disadvantageous, so who knows what the rate was. We can already build viruses, of course. Even if a mix of chemicals would produce a self-replicating molecules, blindingly quickly, say a million years, it would be hard to get a grant to let you wait for it.
Requiring non-living molecules to become cells directly is waving away many, many likely intermediate steps.
First, conditions today are a lot different than they were a billion years ago - our air is full of that highly reactive poison oxygen, for one thing. Second, how do you abiogenesis never happens. But if it did, the new molecules would not find a nice empty niche to expand into, but instead they’d find lots of hungry creatures. So, poof, no new life.
As for other planets, one per solar system seems like enough to me. Nothing has turned up on Mars, yet, but we have no clue about other places. If there was thriving intelligent life 100 million years ago on a planet 50 light years away, they might have said the same thing you do. Why do you think it likely there would be two civilizations using radio in such a small part of the galaxy?
And has already been mentioned, abiogenesis has nothing to do with evolution. Still, expecting us to know exactly how life began in the remote past only 60 years or so after the discovery of DNA is a bit much.
Well, it does have something to do with evolution. If there was no plausible mechanism for complex life to arise from simple life, then all the hypotheses about abiogenesis would have to have modern, complex organisms arising spontaneously, which would be very hard to swallow in a naturalistic scenario.
Evolution makes naturalistic abiogenesis a lot more plausible since only very simple mutating replicators need to arise, and then evolution can take it from there. If there was not evolution, viable hypotheses about life’s origins would look very different.
Would not the ‘testing’ of evolution (if successful) only serve to prove intelligent design (by man)?
No, it would not.
How would you set up a repeatable/confirm-able test then that would not involve man(kind) influencing evolution through his/her intelligence and in doing so proving intelligent design as fact?
And there’s evidence of enough exchange of material between Earth and Mars - and even Earth-Europa - to suspect that if life is found in those places, it may have a common origin with life here.
ID does not hold that intelligent humans have guided evolution, and examples of human use of intelligence to design things are not evidence that supports ID.