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26. Natural Theory / D. Laws of Nature / 3. Laws and Generalities

[differences between general truths and real laws]

8 ideas
We don't use laws to make predictions, we call things laws if we make predictions with them [Goodman]
     Full Idea: Rather than a sentence being used for prediction because it is a law, it is called a law because it is used for prediction.
     From: Nelson Goodman (Fact, Fiction and Forecast (4th ed) [1954], p.21), quoted by Stathis Psillos - Causation and Explanation §5.4
     A reaction: This smacks of dodgy pragmatism, and sounds deeply wrong. The perception of a law has to be prior to making the prediction. Why do we make the prediction, if we haven't spotted a law. Goodman is mesmerised by language instead of reality.
Newton's First Law refers to bodies not acted upon by a force, but there may be no such body [Armstrong]
     Full Idea: Newton's First Law of Motion tells us what happens to a body which is not acted upon by a force. Yet it may be that the antecedent of the law is never instantiated. It may be that every body that there is, is acted upon by some force.
     From: David M. Armstrong (What is a Law of Nature? [1983], 02.7)
Laws of nature are just descriptions of how things are disposed to behave [Ellis]
     Full Idea: The laws of nature must be supposed to be just descriptions of the ways in which things are intrinsically disposed to behave: of how they would behave if they existed as closed and isolated systems.
     From: Brian Ellis (The Metaphysics of Scientific Realism [2009], 3)
     A reaction: I agree with this, and therefore take 'laws of nature' to be eliminable from any plausible ontology (which just contains the things and their behaviour). Ellis tends to defend laws, when he doesn't need to.
Lawlike sentences are general attributions of disposition to all members of some class [Fetzer]
     Full Idea: Lawlike sentences are conceived as logically general dispositional statements attributing permanent dispositional properties to every member of a reference class. ...Their basic form is that of subjunctive generalizations.
     From: J.H. Fetzer (A World of Dispositions [1977], 3)
     A reaction: I much prefer talk of 'lawlike sentences' to talk of 'laws'. At least they imply that the true generalisations about nature are fairly fine-grained. Why not talk of 'generalisations' instead of 'laws'? Fetzer wants dispositions to explain everything.
Natural laws result from eliminative induction, where enumerative induction gives generalisations [Cohen,LJ, by Psillos]
     Full Idea: Cohen contends that statements that express laws of nature are the products of eliminative induction, where accidentally true generalisations are the products of enumerative induction.
     From: report of L. Jonathan Cohen (The Problem of Natural Laws [1980], p.222) by Stathis Psillos - Causation and Explanation §7.1
     A reaction: The idea is that enumerative induction only offers the support of positive instances, where eliminative induction involves attempts to falsify a range of hypotheses. This still bases laws on observed regularities, rather than essences or mechanisms.
Without laws, how can a dispositionalist explain general behaviour within kinds? [Mumford]
     Full Idea: The problem is how, without general laws, can the dispositionalist explain why generalities in behaviour are true of kinds.
     From: Stephen Mumford (Dispositions [1998], 10.3)
     A reaction: And the answer is to make kinds depend on individuals, and not vice versa, and then point to the necessary patterns that arise from conjunctions of individual dispositions, given their identity in many individuals.
"All gold cubes are smaller than one cubic mile" is a true universal generalisation, but not a law [Psillos]
     Full Idea: The statement "all gold cubes are smaller than one cubic mile" seems to have all the features demanded of a lawlike statement, yet it can hardly be said to express a law. It is a merely true universal generalisation.
     From: Stathis Psillos (Causation and Explanation [2002], §5.3)
     A reaction: Nice example. A trickier case is "all cubes of uranium are smaller than one cubic mile", which sounds like part of a law. It suggests a blurred borderline between the two. How much gold is there in the universe? Is that fact a natural necessity?
Pragmatic laws allow prediction and explanation, to the extent that reality is stable [Leuridan]
     Full Idea: A generalization is a 'pragmatic law' if it allows of prediction, explanation and manipulation, even if it fails to satisfy the traditional criteria. To this end, it should describe a stable regularity, but not necessarily a universal and necessary one.
     From: Bert Leuridan (Can Mechanisms Replace Laws of Nature? [2010], §1)
     A reaction: I am tempted to say of this that all laws are pragmatic, given that it is rather hard to know whether reality is stable. The universal laws consist of saying that IF reality stays stable in certain ways, certain outcomes will ensue necessarily.