What is the power of prediction?

Obviously 'prediction' can mean many different things to different people.
On the most fundamental level, a scientific hypothesis is a testable prediction. It does not hinge on correctly specifying FUTURE conditions. It hinges on being falsifiable.
There must be some way to collect data that will either support or refute it or it isn't a scientific hypothesis.Science advances by eventually refuting established hypotheses. Thus hypotheses are not *confirmed* by evidence, they are *supported* by evidence. They can still be refuted later by new evidence. I know it seems a lot less satisfying than your prediction of exact location of an object in space, but most science doesn't make such black and white predictions.
Science makes predictions for purposes of testing theories, not fortune-telling. The accuracy of prediction tends to be far greater in some sciences (physics) than in others (biology) because some sciences deal with more determinisitic phenomena than others. Even in physics, QM is kind of a cop-out from 'exact prediction' in that it sets limits on our level of certainty regarding the actual physical location of an electron in space. We have to accept that accuracy sometimes has intrinsic limitations beyond our control, so we accept (and be happy) that we can define a space around an atom within which the electron has a 99.99% probability of occurring at any given point in time.Many scientists will argue that *accuracy* (exact correspondence to the real world, or absolute predicatability, if you will) is not a reasonable goal for most empirical science. What we really strive for is *precision* - the ability to make precise measurements that are consistently repeatable. We can gain confidence in our hypotheses through precise and repeated observations that support them, but we can never be sure of accuracy since we may not be testing everything that might affect certain outcomes.So the 'power of prediction' is highly variable across scientific disciplines and is quite dependent on the specifics of the case in question. Since evolution is such a complicated, contingent process with the really large changes buried deep in the past and not directly observable, it may seem to the lay person as if it hasn't very good predictive power. In actually, it does, but it takes a lot more comprehension to understand this predictability than it does to understand that an apple will hit you on the head if you are standing under it when it falls off a tree. The correspondence of molecular and morphological phylogenies alluded to in the OP is such an example. Unless you can grasp just how different these appoaches are for generating a phylogeny, you can't appreciate the tremendous implications of their convergence.

That, of course, is where the religious concept of a 'prediction' and the scientific concept of a 'prediction' differs.The 'scientific' prediction is that a piece of unknown evidence matches certain characteristics. For example, when Einstein came out with his theory of relativity, he predicted that the gravity of the sun would bend light at a certain percentage. Light always was bent at this, but we did not have the ability to measure it at that time.When a solar eclipse came a few years later, we were able to measure the
bending of the light, and sure enough, the light rays were bent almost exactly to the degree Einstein said it would.It is more like forensics than religious prophecy. A better analogy would be that if a certain person had commited a murder, it is predicted that the DNA of the skin sample found underneath the victims nails would match that of a specific person that would be considered the suspect. If the DNA did not match the suspect, the hypthesis that
the he was the murder who the victim scratched would be falsified. If it matched, the hypothesis would become much much stronger.

robinrohan, I ask again, & I'll put it a different way this time because you ignored points I was making.A theory has 10 pieces of evidence in its support, 1-10, & all are equal in their evidential value. Two of them are known before the theories formulation. What about two of the evidences contributes less to the theories veracity than the other eight, given they are all of equal evidential weight? Put another way, someone who knows nothing about the theory comes along & looks at all ten evidences, would he see two evidences contributing less to the theories power if he never knew in advance that they pre-existed the theory?No, of course not. All that evidence should exist if the theory is true, if something should exist it is predictive by nature, & therefore a prediction of that theory. It is irrelevant whether it was known in advance.I understand what you are saying, it seems a bit like predicting that the racehorse Blue Brandy should win the race after it has been run, right? Not a particularly impressive after-the-event prediction. But if we theorise that Blue Brandy was the fastest horse in the race, then a prediction of that theory is that Blue Brandy should win. This prediction is true regardless of whether the race has taken place, or not.Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't

This ungraspability is perhaps the problem. Sounds like something for Percy to ponder.

I did? What on earth are you doing adding an "s" to "evidence"? I do see your point, but I don't think we should call the process you are describing a "prediction." It's very misleading.And I still don't see how such "evidences" add up to a certainty comparable to our knowledge that the earth revolves around the sun. Everytime we send a rocket up we prove that. We can't send a rocket back in time.

robin, It's not misleading, it falls within the definition of the word. It only appears misleading if you have a personal & inflexible definition in the first place. Irrelevant. Nothing in science adds up to a certainty regardless of whether you are looking at past events or atoms consisting mainly of space. You have stopped arguing about "prediction" & moved to the nature & quality of evidence.Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't

My point is not irrelevant. The op asks if some predictions are better than others. Answer: yes. This notion aobut science always being uncertain is a mere pedantry. We are talking about relative certainties. It is MORE certain that the earth revolves around the sun than that TOE with all its ramifications is true.Why is it more certain? Because of the nature of the evidence, that's why. Everybody keeps throwing out the term "congruence," as if all they have to do is mention that and the whole problem's solved. They are going to have to be a little more specific than that.This message has been edited by robinrohan, 03-10-2006 07:05 AM

It's hard for me to comment on this without more a notion of what you mean by a "pattern." For example, what?

I think Message 13 is an important one with regards to prediction. You say that predicting where an object will be in space and time is a strong prediction. My question: Another important point is predictive power. A theory doesn't have to predict something that has yet to come about, it merely needs to have been able to have predicted it. Another way of looking at it is that if we give someone some science training and the details of the theory, yet keep them blind to certain data...will they be able to predict what that data should be?

It really doesn't matter. Consider them 'states' if you will. It could be just a single number. Being able to predict a specific number or even just a small range of numbers 1 out of 10⁷⁴ would suggest some underlying knowledge about how the number was generated, or incredible luck.

There are two ways how prediction could be possible:1. Through scientific/mathematical configuration where probabilities can be achieved through present/available data or information. This is more reliable than by merely guessing. Predicting possible natural occurances nowadays is becoming more and more reliable through present day instruments or gadgets, "plus" the application of mathematical probabilities.2. Through prophecy. This is not actually a method because it can not be done by just anybody else. It is an ability only those who received the "gift" of the power can do it.So, and therefore, we must denounce whatever or whoever claims that he or she can predict the future without the benefit of being gifted with the power of prophecies. Only the prophets (not the psychics) who can prophesize the future without consulting any scientific references.

robin, That's not what it is irrelevant too, now, is it?It is irrelevant because I am arguing against quotes like this: & not the value of evidence/predictions.I agree the answer is yes. But do you accept that they are predictions? Then we can move on.MarkThis message has been edited by mark24, 03-10-2006 08:50 AM

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There are 10 kinds of people in this world; those that understand binary, & those that don't

My favourite scientific prediction was Einstein's prediction that light would bend, and that this would be demonstrated at a solar eclipse. I offer this as a valid example of a prediction. http://archive.ncsa.uiuc.edu/...ria/NumRel/EinsteinTest.html

I do think it's important to draw a distinction between different kinds of predictions.In this thread, folks have talked about predictions that are made by a scientific theory, for example, the nested heirarchical pattern of species. This was a classification system that predated Darwinian evolution. Since it is "predicted" by the theory, so the argument goes, it is considered validation of the theory. (I think it's more accurate to describe this kind of a prediction as an explanation, but for present purposes will accept it arguendo.) The problem with this type of argument is that it's possible to construct a theory is such a way that it appears to make this kind of "prediction." And creos have gotten a fair amount of mileage out of doing just that.For example, creos will say that special creation predicts that most mutations will be harmful and then argue that, since most mutations are harmful, that validates their theory. We have to carefully evaluate any post hoc "prediction" of this sort.Another kind of prediction, called a "retrodiction" by some here, is a claim that certain evidence will be discovered that is, as of the time of the prediction, unknown. Einstein's prediction about the bending of light is a wonderful example. These are considerably more forceful, because they are predictions whose accuracy is not yet known. The more detailed such a prediction is, or the more unlikely it would appear that the prediction should be accurate, the more power it has toward validating the theory when the prediction is borne out.Here is a partial list of some of the hundred of predictions of this sort that evolution has made that have been fulfilled. Page Not Found | Department of Chemistry

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Those who would sacrifice an essential liberty for a temporary security will lose both, and deserve neither. -- Benjamin Franklin

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The problem with this type of argument is that it's possible to construct a theory is such a way that it appears to make this kind of "prediction."

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That is a good point. It is possible that a given theory may be constructed specifically to explain a certain set of facts that are already known.However, I don't think that is the case for the theory of evolution and the nested heirarchical classification of species. I might be wrong, but I don't think the nested hierarchy was foremost in Darwin's thoughts when he developed his theory. I think he was thinking mainly on Malthusian lines. In that case, the nested heirarchical classification would be a bona fide prediction of the theory.Another point that must be made is even if a theory is concocted to explain currently known phenomena (and, of course, that is exactly how theories come to be), it is still an impressive feat; there isn't usually any a priori reason to suppose that any set of phenomena can be explained by a common theory. In the case of evolution, there was no reason to suppose that there could be a idea that explained, say, the biogeographic distribution of species, the laws of heredity, and the nested heirarchy all at once. So, even if the theory of evolution was consciously constructed to explain all these things, it is still quite an impressive achievement (although not as impressive as a true prediction) and should count for something.

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"Intellectually, scientifically, even artistically, fundamentalism -- biblical literalism -- is a road to nowhere, because it insists on fidelity to revealed truths that are not true." -- Katha Pollitt