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14. Science / A. Basis of Science / 4. Prediction

[predicting events as support for a theory]

18 ideas
Successful prediction shows proficiency in nature [Leibniz]
     Full Idea: He who can finally make predictions with success must be said to have become sufficiently proficient in nature.
     From: Gottfried Leibniz (On Perceptions [1680], A6.4.1398), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 7
     A reaction: Is prediction achieved by knowledge of laws, or knowledge of essences and powers? The trouble with most laws is that they permit exceptions. 'Things fall, unless prevented' etc.
Explanatory facts also predict, and predictive facts also explain [Hempel, by Okasha]
     Full Idea: Hempel said every scientific explanation is potentially a prediction - it would have predicted the phenomenon in question, had it not already been known. But also the information used to make a prediction is potentially an explanation.
     From: report of Carl Hempel (Aspects of Scientific Explanation [1965]) by Samir Okasha - Philosophy of Science: Very Short Intro (2nd ed) 3
     A reaction: Sounds too neatly glib to be quite true. If you explain a single event there is nothing to predict. You might predict accurately from a repetitive pattern, with no understanding at all of the pattern.
Correlations can provide predictions, but only causes can give explanations [Salmon]
     Full Idea: Various kinds of correlations exist that provide excellent bases for prediction, but because no suitable causal relations exist (or are known), these correlations do not furnish explanation.
     From: Wesley Salmon (Four Decades of Scientific Explanation [1989], 2.3)
     A reaction: There may be problem cases for the claim that all explanations are causal, but I certainly think that this idea is essentially right. Prediction can come from induction, but inductions may be true and yet baffling.
Most predictions are uninteresting, and are only sought in order to confirm a theory [Putnam]
     Full Idea: Scientists want successful predictions in order to confirm their theories; they do not want theories in order to obtain the predictions, which are in some cases of not the slightest interest in themselves.
     From: Hilary Putnam (Philosophy of Logic [1971], Ch.8)
     A reaction: Equally, we might only care about the prediction, and have no interest at all in the theory. Farmers want weather predictions, not a PhD in meteorology.
Unpredictability doesn't entail inexplicability, and predictability doesn't entail explicability [MacIntyre]
     Full Idea: Just as unpredictability does not entail inexplicability, so predictability does not entail explicability.
     From: Alasdair MacIntyre (After Virtue: a Study in Moral Theory [1981], Ch. 8)
     A reaction: The second half is not quite as obvious as the first. The location of lightning strikes is an example of the first. He gives examples of the second, but they all seem to be very complex cases which might be explained, if only we knew enough.
The 'symmetry thesis' says explanation and prediction only differ pragmatically [Ruben]
     Full Idea: The 'symmetry thesis' holds that there is only a pragmatic, or epistemic, but no logical, difference between explaining and predicting. …The only difference is in what the producer of the deduction knows just before the deduction is produced.
     From: David-Hillel Ruben (Explaining Explanation [1990], Ch 4)
     A reaction: He cites Mill has holding this view. It seems elementary to me that I can explain something but not predict it, or predict it but not explain it. The latter case is just Humean habitual induction.
It is more impressive that relativity predicted Mercury's orbit than if it had accommodated it [Lipton]
     Full Idea: We are more impressed by the fact that the special theory of relativity was used to predict the shift in the perihelion of Mercury than we would have been if we knew that the theory was constructed in order to account for that effect.
     From: Peter Lipton (Inference to the Best Explanation (2nd) [2004], 10 'The fudging')
     A reaction: Lipton has a nice discussion of the relative merits of predicting data and accommodating it. He invites astrologers to predict events, rather than accommodate past ones.
Predictions are best for finding explanations, because mere accommodations can be fudged [Lipton]
     Full Idea: Accommodations are often worth less than predictions, because only they have to face the possibility that the best explanation of the fit between the theory and data is that the theoretical system was fudged.
     From: Peter Lipton (Inference to the Best Explanation (2nd) [2004], 11 'Circularity')
     A reaction: Lipton illuminatingly explores the discovery by Semmelweiss of the cause of childbed fever. He predicted various explanations, and tested them out in a hospital. It clicks when the prediction occurs.
Explanation does not entail prediction [Flanagan]
     Full Idea: Explanation does not entail prediction.
     From: Owen Flanagan (The Problem of the Soul [2002], p. 73n)
     A reaction: Presumably the inverse of this is also true, as we might be able to predict through pure induction, without knowing why something happened. We predict that smoking is likely to cause cancer. Complex things might be explicable but unpredictable.
The possibility of prediction rests on determinism [Dupré]
     Full Idea: Determinism is the metaphysical underlay of the possibility of prediction.
     From: John Dupré (The Disorder of Things [1993], Intro)
     A reaction: Not convinced. There might be micro-indeterminacies which iron out into macro-regularities.
A good barometer will predict a storm, but not explain it [Psillos]
     Full Idea: There can be predictions without explanations, as when a barometer successfully predicts storms, but on its own it does not explain them.
     From: Stathis Psillos (Causation and Explanation [2002], §8.8)
     A reaction: Actually, barometers contribute to explanations. A reasonable predictor might offer no explanation ('if he's out, she's probably out too'), but an infallible predictor is almost certain to involve causation, which helps a lot in explanation.
If we say where Mars was two months ago, we offer an explanation without a prediction [Psillos]
     Full Idea: There can be explanations without predictions, as when we explain a previous position of Mars from its present one, plus a law.
     From: Stathis Psillos (Causation and Explanation [2002], §8.9)
     A reaction: If we don't mind stretching the word, I think we can 'predict' the past, as where I predict the location of an Egyptian tomb from my study of papyruses.
Explanation predicts after the event; prediction explains before the event [Bird]
     Full Idea: Explanation is prediction after the event and prediction is explanation before the event.
     From: Alexander Bird (Philosophy of Science [1998], Ch.2)
     A reaction: A nice slogan, fitting Hempel's 'covering law' view of explanation. It doesn't seem quite right, because explanations and predictions are couched in very different language. Prediction implies an explanation; explanation implies a prediction.
Predictions give the 'content' of theories, which can then be 'equivalent' or 'adequate' [Button]
     Full Idea: The empirical 'content' of a theory is all its observable predictions. Two theories with the same predictions are empirically 'equivalent'. A theory which gets it all right at this level is empirically 'adequate'.
     From: Tim Button (The Limits of Reason [2013], 05.1)
The theory of evolution was accepted because it explained, not because of its predictions [Ladyman/Ross]
     Full Idea: Darwin's theory of evolution was accepted by the scientific community because of its systematizing and explanatory power, and in spite of its lack of novel predictive success.
     From: J Ladyman / D Ross (Every Thing Must Go [2007], 2.1.3)
     A reaction: I am keen on the centrality of explanation to all of our thinking, metaphysical as well as physical, so I like this one. In general I like accounts of science that pay more attention to biology, and less to physics.
What matters is whether a theory can predict - not whether it actually does so [Ladyman/Ross]
     Full Idea: We suggest a modal account of novel prediction. That a theory could predict some unknown phenomenon is what matters, not whether it actually did so predict.
     From: J Ladyman / D Ross (Every Thing Must Go [2007], 2.1.3)
     A reaction: They also emphasise predicting new types of thing, rather than particular items. Some theories are powerful on explanation, but not so concerned with prediction. See Idea 14915.
If a theory can be fudged, so can observations [Scerri]
     Full Idea: A theorist may have designed his theory to fit the facts, but is it not equally possible for observers to be influenced by a theory in their report of experimental facts?
     From: Eric R. Scerri (The Periodic Table [2007], 05 'Power')
     A reaction: This is in reply to Lipton's claim that prediction is better than accommodation because of the 'fudging' problem. The reply is that you might fudge to achieve a prediction. If it was correct, that wouldn't avoid the charge of fudging.
A system can infer the structure of the world by making predictions about it [New Sci.]
     Full Idea: If we can train a system for prediction, it can essentially infer the structure of the world it's looking at by doing this prediction.
     From: New Scientist writers (New Scientist articles [2013], 2015.12.12)
     A reaction: [AI expert] This seems to be powerful support for the centrality of mathematical laws of nature in achieving understanding of the world. We may downplay the 'mere' ability to predict, but this idea says that the rewards of prediction are very great.