| 5047 | The world is physically necessary, as its contrary would imply imperfection or moral absurdity [Leibniz] |
| Full Idea: Although the world is not metaphysically necessary, such that its contrary would imply a contradiction or logical absurdity, it is necessary physically, that is, determined in such a way that its contrary would imply imperfection or moral absurdity. | |
| From: Gottfried Leibniz (On the Ultimate Origination of Things [1697], p.139) | |
| A reaction: How does Leibniz know things like this? The distinction between 'metaphysical' necessity and 'natural' (what he calls 'physical') necessity is a key idea. But natural necessity is controversial. See 'Essentialism'. |
| 5594 | Natural necessity is the unconditioned necessity of appearances [Kant] |
| Full Idea: The unconditioned necessity of appearances can be called natural necessity. | |
| From: Immanuel Kant (Critique of Pure Reason [1781], B447/A419) | |
| A reaction: Kant can call it what he likes, but this isn't what we mean by 'natural necessity'. We mean a feature of reality, even if we can only use appearances to infer that feature. As usual, they can't tell their ontology from their epistemology. |
| 15884 | Laws of nature remain the same through any conditions, if the underlying mechanisms are unchanged [Harré] |
| Full Idea: A statement is a law of nature if it is true in all those worlds which differ only as to their initial conditions, that is in which the underlying mechanisms of nature are the same. | |
| From: Rom Harré (Laws of Nature [1993], 4) | |
| A reaction: Harré takes it that laws of nature have to be necessary, by definition. I like this way of expressing natural necessity, in terms of 'mechanisms' rather than of 'laws'. Where do the mechanisms get their necessity? |
| 4797 | Instead of being regularities, maybe natural laws are the weak a posteriori necessities of Kripke [Kripke, by Psillos] |
| Full Idea: By defending a posteriori necessary statements, Kripke introduced the concept of a necessity in nature that was weaker than logical necessity; ..as a result, the dominant view of laws as mere regularities started to be seriously challenged. | |
| From: report of Saul A. Kripke (Naming and Necessity lectures [1970]) by Stathis Psillos - Causation and Explanation §6.1 | |
| A reaction: Most of Kripke's examples of discovered necessities seem to be identities, which seem to be as strong as any logical necessity. I'm not sure I can make sense of a 'less strong necessity'. Necessity sounds all-or-nothing to me. |
| 17037 | Physical necessity may be necessity in the highest degree [Kripke] |
| Full Idea: Physical necessity might turn out to be necessity in the highest degree. But that's a question which I don't wish to prejudge. | |
| From: Saul A. Kripke (Naming and Necessity lectures [1970], Lecture 2) | |
| A reaction: Presumably necessity 'in the highest degree' is 'metaphysical' necessity, but Kripke is a bit coy about that. This is the germ of modern scientific essentialism. |
| 17058 | What many people consider merely physically necessary I consider completely necessary [Kripke] |
| Full Idea: My third lecture suggests that a good deal of what contemporary philosophy regards as mere physical necessity is actually necessary tout court. | |
| From: Saul A. Kripke (Naming and Necessity notes and addenda [1972], Add (g)) | |
| A reaction: He avoids the term 'metaphysically necessary', which most people would not use for this point. |
| 4970 | What is often held to be mere physical necessity is actually metaphysical necessity [Kripke] |
| Full Idea: My third lecture suggests that a good deal of what contemporary philosophy regards as mere physical necessity is actually necessary 'tout court'. | |
| From: Saul A. Kripke (Naming and Necessity notes and addenda [1972], Add (g)) | |
| A reaction: This huge claim rides in on the back of Kripke's very useful clarifications. It is the 'new essentialism', and seems to me untenable in this form. There is no answer to Hume's request for evidence of necessity. Why can't essences (and laws) change? |
| 15214 | Natural necessity is not logical necessity or empirical contingency in disguise [Harré/Madden] |
| Full Idea: Natural necessity is neither a mere reflection of logical necessity nor a roundabout way of referring to empirical contingency. | |
| From: Harré,R./Madden,E.H. (Causal Powers [1975], 1.I.B) | |
| A reaction: They offer a strong defence of natural necessity, which is basic to their scientific essentialism. The key point is that they, unlike some others, are not defending metaphysical necessity about nature, but finding a different type of necessity. Good. |
| 15221 | The relation between what a thing is and what it can do or undergo relate by natural necessity [Harré/Madden] |
| Full Idea: The relation between what a thing is and what it is capable of doing and undergoing is naturally necessary. | |
| From: Harré,R./Madden,E.H. (Causal Powers [1975], 1.II.C) | |
| A reaction: Note that this was written in 1975, and in no way rests of Kripkean notions of rigid designation and necessary identities. Needs thought, but I take it to be an appealing proposal. |
| 15224 | A necessity corresponds to the nature of the actual [Harré/Madden] |
| Full Idea: There is a necessity corresponding to the nature of the actual. | |
| From: Harré,R./Madden,E.H. (Causal Powers [1975], 1.III.C) | |
| A reaction: A nice slogan for the assertion of a genuine and distinct natural necessity. Hence every possible world will have its own distinctive natural necessity. If the actual contains the possible, then there are possible new natural necessities in the actual! |
| 15232 | Natural necessity is when powerful particulars must produce certain results in a situation [Harré/Madden] |
| Full Idea: When the natures of the operative powerful particulars, the constraining or stimulating effect of conditions and so on are offered as the grounds for the judgement that a certain effect cannot but happen (or fail), we have natural necessity. | |
| From: Harré,R./Madden,E.H. (Causal Powers [1975], 1.V.B) | |
| A reaction: This is the view I subscribe to, the really right bit of scientific essentialism. Can this view be proved? Hm. I take the opposite view to be the misguided Humean idea that if you can imagine it not happening, then it might not happen. Firey furnace. |
| 15288 | People doubt science because if it isn't logically necessary it seems to be absolutely contingent [Harré/Madden] |
| Full Idea: At the basis of all doubts about the rationality of science lies the idea that there is no rational resting place between logical necessity and absolute contingency. | |
| From: Harré,R./Madden,E.H. (Causal Powers [1975], 7.III) | |
| A reaction: I'm struck by the fact that when someone says "I have to go now", they express a necessity. Are there thousands of types of necessity, or one conditional necessity resting on thousands of different foundations? |
| 15289 | Property or event relations are naturally necessary if generated by essential mechanisms [Harré/Madden] |
| Full Idea: The relationship between co-existing properties or successive events or states is naturally necessary when understood by scientists to be related by generative mechanisms, whose structure and components constitute the essential natures of the world. | |
| From: Harré,R./Madden,E.H. (Causal Powers [1975], 7.III) | |
| A reaction: Does that mean that the relationship between an actual state and a possible state is metaphysically necessary, rather than naturally necessary? I think we need dispositions to be part of actuality, and hence replace 'co-existing' with 'possible'. |
| 11978 | Causal necessities hold in all worlds compatible with the laws of nature [Lewis] |
| Full Idea: Just as a sentence is necessary if it holds in all worlds, so it is causally necessary if it holds in all worlds compatible with the laws of nature. | |
| From: David Lewis (Counterpart theory and Quant. Modal Logic [1968], V) | |
| A reaction: I don't believe in the so-called 'laws of nature', so I'm not buying that. Is there no distinction in Lewis's view between those sentences which must hold, and those which happen to hold universally? |
| 2730 | Because 'gold is malleable' is necessary does not mean that it is analytic [Audi,R] |
| Full Idea: Taking the proposition that gold is malleable to be necessary does not commit one to considering it analytic. | |
| From: Robert Audi (Epistemology: contemporary introduction [1998], IV p.116) |
| 14676 | Nomological necessity is expressed with intransitive relations in modal semantics [Salmon,N] |
| Full Idea: Intransitive relations are introduced into modal semantics for the purposes of interpreting various 'real' or restricted types of modalities, such as nomological necessity. | |
| From: Nathan Salmon (The Logic of What Might Have Been [1989], II) | |
| A reaction: The point here is that the (so-called) 'laws of nature' are held to change from world to world, so necessity in one could peter out in some more remote world, rather than being carried over everywhere. A very Humean view of such things. |
| 11085 | Nomological necessity is truth in all logically possible worlds with our laws [Hanna] |
| Full Idea: Physical or nomological necessity is the truth of a sentence in all logically possible worlds governed by our actual laws of nature. | |
| From: Robert Hanna (Rationality and Logic [2006], 6.6) | |
| A reaction: Personally I think 'natural necessity' is the best label for this, as it avoids firm commitment to reductive physicalism, and it also avoids commitment to actual necessitating laws. |
| 14552 | Relations are naturally necessary when they are generated by the essential mechanisms of the world [Mumford/Anjum] |
| Full Idea: The relationship between co-existing properties or successive events or states is naturally necessary when they are understood by scientists to be related in fact by generative mechanisms, whose structures constitute the essential nature of things. | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 7.3) | |
| A reaction: This is the view I espouse. It doesn't follow that those mechanisms have necessary existence. Given those mechanisms, they can only behave in that way, because behaving in some way is precisely what they are. |