| 3425 | Reduction has been defined as deriving one theory from another by logic and maths [Nagel,E, by Kim] |
| Full Idea: Ernest Nagel defines reduction as the possibility of deriving all laws of one theory by logic and mathematics to another theory, with appropriate 'bridging principles' (either definitions, or empirical laws) connecting the expressions of the two theories. | |
| From: report of Ernest Nagel (The Structure of Science [1961]) by Jaegwon Kim - Philosophy of Mind p.213 | |
| A reaction: This has been labelled as 'weak' reduction, where 'strong' reduction would be identity, as when lightning is reduced to electrical discharge. You reduce x by showing that it is y in disguise. |
| 6550 | Reduction requires that an object's properties consist of its constituents' properties and relations [Sellars] |
| Full Idea: The 'Principle of Reducibility' says if an object is a system of objects, then every property of the object must consist in the fact that its constituents have such and such qualities and such and such relations | |
| From: Wilfrid Sellars (Philosophy and Scientific Image of Man [1962], p.27), quoted by William Lycan - Consciousness | |
| A reaction: This sounds to me a more promising attitude to reduction than all this talk of Ernest Nagel's 'Bridge Laws'. If we ask HOW a higher level property arises because of a lower level property, we can describe a mechanism rather than a law. |
| 5791 | Reduction is either by elimination, or by explanation [Searle] |
| Full Idea: One sense of 'reduction' is eliminative, in getting rid of a phenomenon by showing that it is really something else (as the earth's rotation eliminates 'sunsets'), but another sense does not get rid of it (as in the explanation of solidity by molecules). | |
| From: John Searle (The Mystery of Consciousness [1997], Ch.2) | |
| A reaction: These are bad analogies. You can't 'eliminate' a sunset - you just accept that the event is relative to a viewpoint. If we are discussing ontology, we will not admit the existence of sunsets, but we won't have an ontological category of 'solidity' either. |
| 5799 | Eliminative reduction needs a gap between appearance and reality, as in sunsets [Searle] |
| Full Idea: Eliminative reductions require a distinction between reality and appearance; for example, the sun appears to set but the reality is that the earth rotates. | |
| From: John Searle (The Mystery of Consciousness [1997], Concl 2.10) | |
| A reaction: A bad analogy. You don't 'eliminate' sunsets. It is just 'Galilean' relativity - you thought it was your train moving, then you discover it was the other one. You don't eliminate hallucinations when you show that they don't correspond to reality. |
| 3473 | Reduction can be of things, properties, ideas or causes [Searle] |
| Full Idea: I find at least five different senses of "reduction" in the literature - ontological (genes/DNA), property ontological (heat/mean molecular energy), theoretical (gas laws/statistics), logical/definitional (average plumber), and causal (solids/molecules). | |
| From: John Searle (The Rediscovery of the Mind [1992], Ch. 5.II) | |
| A reaction: A useful pointer towards some much needed clearer thought about reduction. It is necessary to cross reference this list against reductions which are either ontological or epistemological or linguistic. |
| 6984 | Smooth reductions preserve high-level laws in the lower level [Jackson] |
| Full Idea: In a 'smooth' reduction the laws of the reduced theory (thermodynamics of gases) are pretty much preserved in (and isomorphic with) the corresponding laws in the reducing theory (molecular or kinetic theory of gases). | |
| From: Frank Jackson (From Metaphysics to Ethics [1998], Ch.3) | |
| A reaction: Are the 'laws' of weather (e.g. linking humidity, temperature and pressure to rainfall) preserved at the level of physics? One might say that they are not preserved, but they are not lost either (they just fade away). Contradictions would be worrying. |
| 2317 | Reductionism is good on light, genes, temperature and transparency [Kim, by PG] |
| Full Idea: Examples where reductionism seems to give a good account of things are light, genes, temperature and transparency. | |
| From: report of Jaegwon Kim (Mind in a Physical World [1998], §1 p.025) by PG - Db (ideas) | |
| A reaction: This a fairly simple examples, thoroughly confirmed by science a long time ago. Life is a nicer example, because it is more complex and less obvious, but pretty much beyond dispute these days. |
| 3990 | The whole truth supervenes on the physical truth [Lewis] |
| Full Idea: The whole truth supervenes on the physical truth. | |
| From: David Lewis (Lewis: reduction of mind (on himself) [1994], p.412) | |
| A reaction: This seems to me the central truth about brains, and we should not be lured into abandoning it. We should not, however, exclude the possibility that there is a non-physical reality. |
| 8607 | Supervenience is reduction without existence denials, ontological priorities, or translatability [Lewis] |
| Full Idea: Supervenience is a stripped down form of reductionism, unencumbered by dubious denials of existence, claims of ontological priority, or claims of translatability. | |
| From: David Lewis (New work for a theory of universals [1983], 'Dup,Sup,Div') | |
| A reaction: Interesting. It implies that the honest reductionist (i.e. me) should begin by asserting supervience, and only at a second stage go on to deny a bit of existence, loudly affirm priorities, and offer translations. Honest toil. |
| 5516 | Reduction can be by identity, or constitution, or elimination [Parfit, by PG] |
| Full Idea: We can distinguish Identifying Reductionism (as in 'persons are bodies'), or Constitutive Reductionism (as in 'persons are distinct, but consist of thoughts etc.'), or Eliminative Reductionism (as in 'there are no persons, only thoughts etc.'). | |
| From: report of Derek Parfit (The Unimportance of Identity [1995], p.295) by PG - Db (ideas) | |
| A reaction: Constitutive Reductionism seems the most common one, as in 'chemistry just consists of lots of complicated physics'. He doesn't mention bridge laws, which are presumably only required in more complicated cases of constitutive reduction. |
| 4986 | A weaker kind of reductionism than direct translation is the use of 'bridge laws' [Kirk,R] |
| Full Idea: If multiple realisability means that psychological terms cannot be translated into physics, one weaker kind of reductionism resorts to 'bridge laws' which link the theory to be reduced to the reducing theory. | |
| From: Robert Kirk (Mind and Body [2003], §3.8) | |
| A reaction: It seems to me that reduction is all-or-nothing, so there can't be a 'weaker' kind. If they are totally separate but linked by naturally necessary laws (e.g. low temperature and ice), they are supervenient, but not reducible to one another. |
| 6531 | Institutions are not reducible as types, but they are as tokens [Lycan] |
| Full Idea: Institutional types are irreducible, though I assume that institutional tokens are reducible in the sense of strict identity, all the way down to the subatomic level. | |
| From: William Lycan (Consciousness [1987], 4.3) | |
| A reaction: This seems a promising distinction, as the boundaries of 'institutions' disappear when you begin to reduce them to lower levels (cf. Idea 4601), and yet plenty of institutions are self-evidently no more than physics. Plants are invisible as physics. |
| 6532 | Types cannot be reduced, but levels of reduction are varied groupings of the same tokens [Lycan] |
| Full Idea: If types cannot be reduced to more physical levels, this is not an embarrassment, as long as our institutional categories, our physiological categories, and our physical categories are just alternative groupings of the same tokens. | |
| From: William Lycan (Consciousness [1987], 4.3) | |
| A reaction: This is a self-evident truth about a car engine, so I don't see why it wouldn't apply equally to a brain. Lycan's identification of the type as the thing which cannot be reduced seems a promising explanation of much confusion among philosophers. |
| 21110 | An understanding of the most basic physics should explain all of the subject's mysteries [Krauss] |
| Full Idea: Once we understood the fundamental laws that govern forces of nature at its smallest scales, all of these current mysteries would be revealed as natural consequences of these laws. | |
| From: Lawrence M. Krauss (A Universe from Nothing [2012], 08) | |
| A reaction: This expresses the reductionist view within physics itself. Krauss says the discovery that empty space itself contains energy has led to a revision of this view (because that is not part of the forces and particles studied in basic physics). |
| 7017 | The reductionist programme dispenses with levels of reality [Heil] |
| Full Idea: The reductionist programme dispenses with levels of reality. | |
| From: John Heil (From an Ontological Point of View [2003], 04.3) | |
| A reaction: Fodor, for example, claims that certain causal laws only operate at high levels of reality. I agree with Heil's idea - the notion that there are different realities around here that don't connect properly to one another is philosopher's madness. |
| 15050 | Reduction might be producing a sentence which gets closer to the logical form [Fine,K] |
| Full Idea: One line of reduction is logical analysis. To say one sentence reduces to another is to say that they express the same proposition (or fact), but the grammatical form of the second is closer to the logical form than the grammatical form of the first. | |
| From: Kit Fine (The Question of Realism [2001], 3) | |
| A reaction: Fine objects that S-and-T reduces to S and T, which is two propositions. He also objects that this approach misses the de re ingredient in reduction (that it is about the things themselves, not the sentences). It also overemphasises logical form. |
| 15051 | Reduction might be semantic, where a reduced sentence is understood through its reduction [Fine,K] |
| Full Idea: A second line of reduction is semantic, and holds in virtue of the meaning of the sentences. It should then be possible to acquire an understanding of the reduced sentence on the basis of understanding the sentences to which it reduces. | |
| From: Kit Fine (The Question of Realism [2001], 3) | |
| A reaction: Fine says this avoids the first objection to the grammatical approach (see Reaction to Idea 15050), but still can't handle the de re aspect of reduction. Fine also doubts whether this understanding qualifies as 'reduction'. |
| 15052 | Reduction is modal, if the reductions necessarily entail the truth of the target sentence [Fine,K] |
| Full Idea: The third, more recent, approach to reduction is a modal matter. A class of propositions will reduce to - or supervene upon - another if, necessarily, any truth from the one is entailed by truths from the other. | |
| From: Kit Fine (The Question of Realism [2001], 3) | |
| A reaction: [He cites Armstrong, Chalmers and Jackson for this approach] Fine notes that some people reject supervenience as a sort of reduction. He objects that this reduction doesn't necessarily lead to something more basic. |
| 15056 | The notion of reduction (unlike that of 'ground') implies the unreality of what is reduced [Fine,K] |
| Full Idea: The notion of ground should be distinguished from the strict notion of reduction. A statement of reduction implies the unreality of what is reduced, but a statement of ground does not. | |
| From: Kit Fine (The Question of Realism [2001], 5) | |
| A reaction: That seems like a bit of a caricature of reduction. If you see a grey cloud and it reduces to a swarm of mosquitoes, you do not say that the cloud was 'unreal'. Fine is setting up a stall for 'ground' in the metaphysical market. We all seek structure. |
| 18539 | Our categories lack the neat arrangement needed for reduction [Heil] |
| Full Idea: Categories we use to describe and explain our universe do not line up in the neat way reductive schemes require. | |
| From: John Heil (The Universe as We Find It [2012], 13.2) | |
| A reaction: He takes reduction to be largely a relation between our categories, rather than between entities, so he is bound to get this result. He may be right. |
| 7508 | Good reductionism connects fields of knowledge, but doesn't replace one with another [Pinker] |
| Full Idea: Good reductionism (also called 'hierarchical reductionism') consists not of replacing one field of knowledge with another, but of connecting or unifying them. | |
| From: Steven Pinker (The Blank Slate [2002], Ch.4) | |
| A reaction: A nice simple clarification. In this sense I am definitely a reductionist about mind (indeed, about everything). There is nothing threatening to even 'spiritual' understanding by saying that it is connected to the brain. |
| 14599 | Three types of reduction: Theoretical (of terms), Definitional (of concepts), Ontological (of reality) [Schaffer,J] |
| Full Idea: Theoretical reduction concerns terms found in a theory; Definitional reduction concerns concepts found in the mind; Ontological reduction is independent of how we conceptualize entities, or theorize about them, and is about reality. | |
| From: Jonathan Schaffer (Causation and Laws of Nature [2008], 1) | |
| A reaction: An Aristotelian definition refers to reality, rather than to our words or concepts. |
| 7944 | Reduce by bridge laws (plus property identities?), by elimination, or by reducing talk [Macdonald,C] |
| Full Idea: There are four kinds of reduction: the identifying of entities of two theories by means of bridge or correlation laws; the elimination of entities in favour of the other theory; reducing by bridge laws and property identities; and merely reducing talk. | |
| From: Cynthia Macdonald (Varieties of Things [2005], Ch.3 n5) | |
| A reaction: [She gives references] The idea of 'bridge laws' I regard with caution. If bridge laws are ceteris paribus, they are not much help, and if they are strict, or necessary, then there must be an underlying reason for that, which is probably elimination. |
| 22180 | Multiple realisability is said to make reduction impossible [Okasha] |
| Full Idea: Philosophers have often invoked multiple realisability to explain why psychology cannot be reduced to physics or chemistry, but in principle the explanation works for any higher-level science. | |
| From: Samir Okasha (Philosophy of Science: Very Short Intro (2nd ed) [2016], 3) | |
| A reaction: He gives the example of a 'cell' in biology, which can be implemented in all sorts of ways. Presumably that can be reduced to many sorts of physics, but not just to one sort. The high level contains patterns that vanish at the low level. |
| 16345 | That Peano arithmetic is interpretable in ZF set theory is taken by philosophers as a reduction [Halbach] |
| Full Idea: The observation that Peano arithmetic is relatively interpretable in ZF set theory is taken by many philosophers to be a reduction of numbers to sets. | |
| From: Volker Halbach (Axiomatic Theories of Truth [2011], 23) | |
| A reaction: Nice! Being able to express something in a different language is not the same as a reduction. Back to the drawing board. What do you really mean by a reduction? If we model something, we don't 'reduce' it to the model. |