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14. Science / D. Explanation / 2. Types of Explanation / i. Explanations by mechanism

[explanation by revealing underlying mechanisms]

32 ideas
Galileo introduced geometrico-mechanical explanation, based on Archimedes [Galileo, by Machamer/Darden/Craver]
     Full Idea: The modern idea of explaining with mechanisms became current in the 17th century when Galileo articulated a geometrico-mechanical form of explanation based on Archimedes' simple machines. This became the 'mechanical philosophy'.
     From: report of Galileo Galilei (Il Saggiatore ('The Assayer') [1623]) by Machamer,P/Darden,L/Craver,C - Thinking About Mechanisms 5.2
     A reaction: So is Archimedes the source? I would say that mechanical explanation is just commonsense, and is predominant in all human thinking, even in tiny infants.
Explanation is deducing a phenomenon from some nature better known to us [Boyle]
     Full Idea: Explicating a phenomenon is to deduce it from something else in nature more known to us than the thing to be explained by it.
     From: Robert Boyle (The Origin of Forms and Qualities [1666], p.46?), quoted by Peter Alexander - Ideas, Qualities and Corpuscles
     A reaction: Interesting that the word 'deduce' is here, beloved of the 'covering law' view. But this may be deduced from the behaviour of other substances, as the iron filing behaviour may be explained by the magnet itself (or perhaps 'laws' of magnetism).
A machine strikes us as being a rule of movement [Wittgenstein]
     Full Idea: We are accustomed to look on a machine as the expression of a rule of movement.
     From: Ludwig Wittgenstein (Lectures 1930-32 (student notes) [1931], B VII.2)
     A reaction: What a beautiful definition of a machine! I like this because it connects the two halves of my view of the 'essence' of a thing, as derived from Aristotle, as both a causal mechanism and an underlying principle. Cf Turing machines.
Salmon's mechanisms are processes and interactions, involving marks, or conserved quantities [Salmon, by Machamer/Darden/Craver]
     Full Idea: For Salmon mechanisms are composed of processes and interactions. The interactions are identified in terms of transmitted marks and statistical relations, or (more recently) exchanges of conserved quantities.
     From: report of Wesley Salmon (Causality and Explanation [1998], 3.1) by Machamer,P/Darden,L/Craver,C - Thinking About Mechanisms 3.1
     A reaction: They say that Salmon has too little to say about the activities that constitute a mechanism. A 'mark' doesn't sound too promising, but I quite like the exchange of conserved quantities, which gets into the guts of what is going on.
Explanation at the quantum level will probably be by entirely new mechanisms [Salmon]
     Full Idea: My basic feeling about explanation in the quantum realm is that it will involve mechanisms, but mechanisms that are quite different from those that seem to work in the macrocosm.
     From: Wesley Salmon (Four Decades of Scientific Explanation [1989], Pref)
     A reaction: Since I take most explanation to be by mechanisms (or some abstraction analogous to mechanisms), then I think this is probably right (rather than being by new 'laws').
Does an item have a function the first time it occurs? [Salmon]
     Full Idea: In functional explanation, there is a disagreement over whether an item has a function the first time it occurs.
     From: Wesley Salmon (Four Decades of Scientific Explanation [1989], 3.8)
     A reaction: This question arises particularly in evolutionary contexts, and would obviously not generally arise in the case of human artefacts.
Explanations reveal the mechanisms which produce the facts [Salmon]
     Full Idea: I favour an ontic conception of explanation, that explanations reveal the mechanisms, causal or other, that produce the facts we are trying to explain.
     From: Wesley Salmon (Four Decades of Scientific Explanation [1989], 4.1)
     A reaction: [He also cites Coffa and Peter Railton] A structure may explain, and only be supported by causal powers, but it doesn't seem to be the causal powers that do the explaining. Is a peg fitting a hole explained causally?
Causation produces productive mechanisms; to understand the world, understand these mechanisms [Salmon]
     Full Idea: Causal processes, causal interactions, and causal laws provide the mechanisms by which the world works; to understand why certain things happen, we need to see how they are produced by these mechanisms.
     From: Wesley Salmon (Scientific Explanation and the Causal Structure of the World [1984]), quoted by David-Hillel Ruben - Explaining Explanation Ch 7
     A reaction: I don't think I've ever found a better quotation on explanation. That strikes me as correct, and (basically) there is nothing more to be said. I'm not sure about the 'laws'. This is later Wesley Salmon.
Salmon's interaction mechanisms needn't be regular, or involving any systems [Glennan on Salmon]
     Full Idea: While Salmon's mechanisms are processes involving interactions, the interactions are not necessarily regular, and they do not involve the operation of systems.
     From: comment on Wesley Salmon (Scientific Explanation and the Causal Structure of the World [1984]) by Stuart Glennan - Mechanisms 'hierarchical'
     A reaction: This is why modern mechanistic philosophy only began in 2000, despite Wesley Salmon's championing of the roughly mechanistic approach.
Explanations of particular events are not essentialist, as they don't reveal essential structures [Ellis]
     Full Idea: Explanations of particular events in history, geology, or evolution, are causal explanations, requiring belief in some causal mechanisms. But they are not essentialist explanations because they do not seek to lay bare the essential structure of anything.
     From: Brian Ellis (Scientific Essentialism [2001], 4.05)
     A reaction: The explanation might be two-stage, as when we explain an earthquake by a plate boundary rupture, which is in turn explained by a theory of plate techtonics. The relationship between mechanistic and essentialist explanation needs study.
The necessity of Newton's First Law derives from the nature of material things, not from a mechanism [Harré]
     Full Idea: The 'must' of Newton's First Law is different. There is no deeper level relative to the processes described to give a mechanism which generates uniform motion. There is no such mechanism. ..It specifies what it is for something to be a material thing.
     From: Rom Harré (Laws of Nature [1993], 4)
     A reaction: Harré says the law can only exist as part of a network of other ideas.
If the nature of particulars explains their powers, it also explains their relations and behaviour [Harré/Madden]
     Full Idea: If we see that certain powers and capacities are explained by the nature of certain particulars and are necessarily attendant upon them, then we have an explanation of why certain things must go together and happen as they do.
     From: Harré,R./Madden,E.H. (Causal Powers [1975], 4.I)
     A reaction: They are offering this as an account of induction, as well as of explanation, and it is a nice summary of the account which I take to be correct.
Powers and natures lead us to hypothesise underlying mechanisms, which may be real [Harré/Madden]
     Full Idea: Usually in science the powers/natures formula does lead to the imagining of hypothetical mechanisms which might be discovered to be real.
     From: Harré,R./Madden,E.H. (Causal Powers [1975], 9.III)
     A reaction: The underlying mechanism is what I take Aristotle to have proposed, and it is the instinctive explanation by children (charted by Susan Gelman).
We want to know not just the cause, but how the cause operated [Lipton]
     Full Idea: We understand a phenomenon better when we know not just what caused it, but how the cause operated.
     From: Peter Lipton (Inference to the Best Explanation (2nd) [2004], 08 'the guiding')
     A reaction: This is the key point behind the desire for 'mechanism' in explanation. It strikes me as undeniable.
Mechanisms are not just push-pull systems [Machamer/Darden/Craver]
     Full Idea: One should not think of mechanisms as exclusively mechanical (push-pull) systems.
     From: Machamer,P/Darden,L/Craver,C (Thinking About Mechanisms [2000], 1)
     A reaction: The difficulty seems to be that you could broaden the concept of 'mechanism' indefinitely, so that it covered history, mathematics, populations, cultural change, and even mathematics. Where to stop?
Mechanisms are systems organised to produce regular change [Machamer/Darden/Craver]
     Full Idea: Mechanisms are entities and activities organized such that they are productive of regular change from start or set-up to finish or termination conditions.
     From: Machamer,P/Darden,L/Craver,C (Thinking About Mechanisms [2000], 1)
     A reaction: This is their initial formal definition of a mechanism. Note that a mere 'activity' can be included. Presumably the mechanism might have an outcome that was not the intended outcome. Does a random element disqualify it? Are hands mechanisms?
A mechanism explains a phenomenon by showing how it was produced [Machamer/Darden/Craver]
     Full Idea: To give a description of a mechanism for a phenomenon is to explain that phenomenon, i.e. to explain how it was produced.
     From: Machamer,P/Darden,L/Craver,C (Thinking About Mechanisms [2000], 1)
     A reaction: To 'show how' something happens needs a bit of precisification. It is probably analytic that 'showing how' means 'revealing the mechanism', though 'mechanism' then becomes the tricky concept.
Our account of mechanism combines both entities and activities [Machamer/Darden/Craver]
     Full Idea: We emphasise the activities in mechanisms. This is explicitly dualist. Substantivalists speak of entities with dispositions to act. Process ontologists reify activities and try to reduce entities to processes. We try to capture both intuitions.
     From: Machamer,P/Darden,L/Craver,C (Thinking About Mechanisms [2000], 3)
     A reaction: [A quotation of selected fragments] The problem here seems to be the raising of an 'activity' to a central role in ontology, when it doesn't seem to be primitive, and will typically be analysed in a variety of ways.
Descriptions of explanatory mechanisms have a bottom level, where going further is irrelevant [Machamer/Darden/Craver]
     Full Idea: Nested hierachical descriptions of mechanisms typically bottom out in lowest level mechanisms. …Bottoming out is relative …the explanation comes to an end, and description of lower-level mechanisms would be irrelevant.
     From: Machamer,P/Darden,L/Craver,C (Thinking About Mechanisms [2000], 5.1)
     A reaction: This seems to me exactly the right story about mechanism, and it is a story I am associating with essentialism. The relevance is ties to understanding. The lower level is either fully understood, or totally baffling.
Modern mechanism need parts with spatial, temporal and function facts, and diagrams [Glennan]
     Full Idea: Modern champions of mechanisms say models should identify both the parts and their spatial, temporal and functional organisation, ...and the practical importance of diagrams in addition to or in place of linguistic representations of mechanisms.
     From: Stuart Glennan (Mechanisms [2008], 'Discover')
     A reaction: Apparently chemists obtain much more refined models by using mathematics than they did by diagrams or 3D models (let alone verbal descriptions). For that reason, I'm thinking that 'model' might be a better term than 'mechanism'.
Mechanistic philosophy of science is an alternative to the empiricist law-based tradition [Glennan]
     Full Idea: To a significant degree, a mechanistic philosophy of science can be seen as an alternative to an earlier logical empiricist tradition in philosophy of science that gave pride of place to laws of nature.
     From: Stuart Glennan (Mechanisms [2008], 'Intro')
     A reaction: Lovely! Someone who actually spells out what's going on here. Most philosophers are far too coy about explaining what their real game is. Mechanism is fine in chemistry and biology. How about in 'mathematical' physics, or sociology?
Mechanisms are either systems of parts or sequences of activities [Glennan]
     Full Idea: There are two sorts of mechanisms: systems consist of collections of parts that interact to produce some behaviour, and processes are sequences of activities which produce some outcome.
     From: Stuart Glennan (Mechanisms [2008], 'Intro')
     A reaction: [compressed] The second one is important because it is more generic, and under that account all kinds the features of the world that need to be explained can be subsumed. E.g. hyperinflation in an economy is a 'mechanism'.
17th century mechanists explained everything by the kinetic physical fundamentals [Glennan]
     Full Idea: 17th century mechanists said that interactions governed by chemical, electrical or gravitational forces would have to be explicable in terms of the operation of some atomistic (or corpuscular) kinetic mechanism.
     From: Stuart Glennan (Mechanisms [2008], 'Intro')
     A reaction: Glennan says science has rejected this, so modern mechanists do not reduce mechanisms to anything in particular.
Unlike the lawlike approach, mechanistic explanation can allow for exceptions [Glennan]
     Full Idea: One of the advantages of the move from nomological to mechanistic modes of explanation is that the latter allows for explanations involving exception-ridden generalizations.
     From: Stuart Glennan (Mechanisms [2008], 'regular')
     A reaction: The lawlike approach has endless problems with 'ceteris paribus' ('all things being equal') laws, where specifying all the other 'things' seems a bit tricky.
General theories may be too abstract to actually explain the mechanisms [Portides]
     Full Idea: If theoretical models are highly abstract and idealised descriptions of phenomena, they may only represent general features, and fail to explain the specific mechanisms at work in physical systems.
     From: Demetris Portides (Models [2008], 'Current')
     A reaction: [compressed] While there may be an ideal theory that explains everything, it sounds right capturing the actual mechanism (such as the stirrup bone in the ear) is not at all theoretical.
Mechanisms can't explain on their own, as their models rest on pragmatic regularities [Leuridan]
     Full Idea: To model a mechanism one must incorporate pragmatic laws. ...As valuable as the concept of mechanism and mechanistic explanation are, they cannot replace regularities nor undermine their relevance for scientific explanation.
     From: Bert Leuridan (Can Mechanisms Replace Laws of Nature? [2010], §1)
     A reaction: [See Idea 12786 for 'pragmatic laws'] I just don't see how the observation of a regularity is any sort of explanation. I just take a regularity to be something interesting which needs to be explained.
We can show that regularities and pragmatic laws are more basic than mechanisms [Leuridan]
     Full Idea: Summary: mechanisms depend on regularities, there may be regularities without mechanisms, models of mechanisms must incorporate pragmatic laws, and pragmatic laws do not depend epistemologically on mechanistic models.
     From: Bert Leuridan (Can Mechanisms Replace Laws of Nature? [2010], §1)
     A reaction: See Idea 14382 for 'pragmatic' laws. I'm quite keen on mechanisms, so this is an arrow close to the heart, but at this point I say that my ultimate allegiance is to powers, not to mechanisms.
Mechanisms are ontologically dependent on regularities [Leuridan]
     Full Idea: Mechanisms are ontologically dependent on the existence of regularities.
     From: Bert Leuridan (Can Mechanisms Replace Laws of Nature? [2010], §3)
     A reaction: This seems to be the Humean rearguard action in favour of the regularity account of laws. Wrong, but a nice paper. This point shows why only powers (despite their vagueness!) are the only candidate for the bottom level of explanation.
Mechanisms must produce macro-level regularities, but that needs micro-level regularities [Leuridan]
     Full Idea: Nothing can count as a mechanism unless it produces some macro-level regular behaviour. To produce macro-level regular behaviour, it has to rely on micro-level regularities.
     From: Bert Leuridan (Can Mechanisms Replace Laws of Nature? [2010], §5)
     A reaction: This is the core of Leuridan's argument that regularities are more basic than mechanisms. It doesn't follow, though, that the more basic a thing is the more explanatory work it can do. I say mechanisms explain more than low-level regularities do.
A structure won't give a causal explanation unless we know the powers of the structure [Mumford/Anjum]
     Full Idea: Knowing the structure that something has does not in itself causally explain that thing's behaviour unless we also know what sorts of behaviour a thing of that structure can cause.
     From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 6.2)
     A reaction: I agree with this. If you focus on the lowest possible levels of causal explanation, I can see only powers. Whatever you come up with, it had better be something active. Geometry never started any bonfires.
Using mechanisms as explanatory schemes began in chemistry [Weisberg/Needham/Hendry]
     Full Idea: The production of mechanisms as explanatory schemes finds its original home in chemistry.
     From: Weisberg/Needham/Hendry (Philosophy of Chemistry [2011], 5.1)
     A reaction: This is as opposed to mechanisms in biology or neuroscience, which come later.
Thick mechanisms map whole reactions, and thin mechanism chart the steps [Weisberg/Needham/Hendry]
     Full Idea: In chemistry the 'thick' notion of a mechanism traces out positions of electrons and atomic cores, and correlates them with energies, showing the whole reaction. 'Thin' mechanisms focus on a discrete set of intermediate steps.
     From: Weisberg/Needham/Hendry (Philosophy of Chemistry [2011], 5.1)