42 ideas
| 8092 | Logic was merely a branch of rhetoric until the scientific 17th century [Devlin] |
| Full Idea: Until the rise of what we call the scientific method in the seventeenth century, logic was regarded largely as one aspect of rhetoric - a study of how one person't argument could convince another. | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch.11) | |
| A reaction: This may well give the main reason why the Greeks invented logic in the first place. Aristotle wrote a book on rhetoric, and that was where the money was. Leibniz is clearly a key figure in the change of attitude. |
| 15477 | Ontology is highly abstract physics, containing placeholders and exclusions [Martin,CB] |
| Full Idea: Ontology sets out an even more abstract model of how the world is than theoretical physics, a model that has placeholders for scientific results and excluders for tempting confusions. | |
| From: C.B. Martin (The Mind in Nature [2008], 04.6) | |
| A reaction: Most modern metaphysicians accept this account. The interesting (mildly!) question is whether physicists will accept it. If the metaphysics is really rooted in physics, a metaphysical physicist is better placed than a metaphysician knowing some physics. |
| 15471 | Truth is a relation between a representation ('bearer') and part of the world ('truthmaker') [Martin,CB] |
| Full Idea: Truth is a relation between two things - a representation (the truth 'bearer') and the world or some part of it (the 'truthmaker'). | |
| From: C.B. Martin (The Mind in Nature [2008], 03.1) | |
| A reaction: That truth is about representations seems to me to be exactly right. That it is about truthmakers is more controversial. There are well known problems with negative truths, general truths, future truths etc. I'm happy with 'facts'. |
| 8081 | 'No councillors are bankers' and 'All bankers are athletes' implies 'Some athletes are not councillors' [Devlin] |
| Full Idea: Most people find it hard to find any conclusion that fits the following premises: 'No councillors are bankers', and 'All bankers are athletes'. There is a valid conclusion ('Some athletes are not councillors') but it takes quite an effort to find it. | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch. 2) | |
| A reaction: A nice illustration of the fact that syllogistic logic is by no means automatic and straightforward. There is a mechanical procedure, but a lot of intuition and common sense is also needed. |
| 8085 | Modern propositional inference replaces Aristotle's 19 syllogisms with modus ponens [Devlin] |
| Full Idea: Where Aristotle had 19 different inference rules (his valid syllogisms), modern propositional logic carries out deductions using just one rule of inference: modus ponens. | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch. 4) | |
| A reaction: At first glance it sounds as if Aristotle's guidelines might be more useful than the modern one, since he tells you something definite and what implies what, where modus ponens just seems to define the word 'implies'. |
| 8086 | Predicate logic retains the axioms of propositional logic [Devlin] |
| Full Idea: Since predicate logic merely extends propositional logic, all the axioms of propositional logic are axioms of predicate logic. | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch. 4) | |
| A reaction: See Idea 7798 for the axioms. |
| 8091 | Situation theory is logic that takes account of context [Devlin] |
| Full Idea: In many respects, situation theory is an extension of classical logic that takes account of context. | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch. 8) | |
| A reaction: John Barwise is cited as the parent of this movement. Many examples show that logical form is very hard to pin down, because word-meaning depends on context (e.g. 'several crumbs' differs from 'several mountains'). |
| 8087 | Golden ages: 1900-1960 for pure logic, and 1950-1985 for applied logic [Devlin] |
| Full Idea: The period from 1900 to about 1960 could be described as the golden age of 'pure' logic, and 1950 to 1985 the golden age of 'applied' logic (e.g. applied to everyday reasoning, and to theories of language). | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch. 4) | |
| A reaction: Why do we always find that we have just missed the Golden Age? However this supports the uneasy feeling that the golden age for all advances in human knowledge is just coming to an end. Biology, including the brain, is the last frontier. |
| 8089 | Montague's intensional logic incorporated the notion of meaning [Devlin] |
| Full Idea: Montague's intensional logic was the first really successful attempt to develop a mathematical framework that incorporates the notion of meaning. | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch. 8) | |
| A reaction: Previous logics, led by Tarski, had flourished by sharply dividing meaning from syntax, and concentrating on the latter. |
| 8082 | Where a conditional is purely formal, an implication implies a link between premise and conclusion [Devlin] |
| Full Idea: Implication involves some form of link or causality between the antecedent and the consequent of an if-then; normally it says that the conclusion is a consequence of the premise (where conditionals are just defined by 'true' and 'false'). | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch. 2) | |
| A reaction: This distinction is a key one when discussing 'If-then' sentences. Some are merely formal conditionals, but others make real claims about where you can get to from where you are. |
| 8072 | Sentences of apparent identical form can have different contextual meanings [Devlin] |
| Full Idea: "Safety goggles must be worn in the building" is clear enough, but "dogs must always be carried on the escalator" doesn't require us to head off in search of a dog. | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch. 1) | |
| A reaction: A nice illustration of how the requirements of logical form will often take us beyond the strict and literal meaning of a sentence, into context, tone, allusion and subjective aspects. |
| 8075 | Space and time are atomic in the arrow, and divisible in the tortoise [Devlin] |
| Full Idea: The arrow paradox starts with the assumption that space and time are atomic; the tortoise starts with the opposite assumption that space and time are infinitely divisible. | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch. 2) | |
| A reaction: Aquinas similarly covers all options (the cosmos has a beginning, or no beginning). The nature of movement in a space which involves quantum leaps remains metaphysically puzzling. Where is a particle at half of the Planck time? |
| 15484 | A property is a combination of a disposition and a quality [Martin,CB] |
| Full Idea: I take properties to have a dual nature; in virtue of possessing a property, an object possesses both a particular dispositionality and a particular qualitative character. | |
| From: C.B. Martin (The Mind in Nature [2008], 04.6) | |
| A reaction: That leaves you with the question of the relationship between the disposition and the quality. I say you must choose, and I choose the disposition. Qualities (which are partly subjective, obviously) arise from fundamental dispositions. |
| 15478 | Properties are the respects in which objects resemble, which places them in classes [Martin,CB] |
| Full Idea: If objects belong to classes in virtue of resemblances they bear to one another, they resemble one another in virtue of their properties. Objects resemble in some way or respect, and you could think of these ways or respects as 'properties'. | |
| From: C.B. Martin (The Mind in Nature [2008], 04.6) | |
| A reaction: If you pare the universe down to one object with five distinct properties, they resemble nothing, and fail this definition. Resemblance seems like the epistemology, not the ontology. |
| 15483 | Properties are ways particular things are, and so they are tied to the identity of their possessor [Martin,CB] |
| Full Idea: The redness or sphericity of this tomato cannot migrate to another tomato. This is a consequence of the idea that properties are particular ways things are. The identity of a property is bound up with the identity of its possessor. | |
| From: C.B. Martin (The Mind in Nature [2008], 04.6) | |
| A reaction: This is part of his declaration that he believes in tropes. At the very least, properties can be thought of separately, and have second-order properties that don't seem tied to the particulars. |
| 15480 | Objects are not bundles of tropes (which are ways things are, not parts of things) [Martin,CB] |
| Full Idea: The bundle theory for tropes treats properties inappositely as parts of objects. Objects can have parts, but an object's properties are not its parts, they are particular ways the object is. | |
| From: C.B. Martin (The Mind in Nature [2008], 04.6) | |
| A reaction: The 'way an object is' seems a very vague concept. Most things that get labelled as tropes are actually highly complex. Without mention of causal powers I think these discussions drift in a muddle. |
| 15489 | A property that cannot interact is worse than inert - it isn't there at all [Martin,CB] |
| Full Idea: A property that is intrinsically incapable of affecting or being affected by anything else, actual or possible, is not merely a case of inertness - it amounts to a no-thing. | |
| From: C.B. Martin (The Mind in Nature [2008], 06.6) | |
| A reaction: In the end Martin rejects Shoemaker's purely causal account of properties, but he clearly understands Shoemaker's point well. |
| 15487 | If unmanifested partnerless dispositions are still real, and are not just qualities, they can explain properties [Martin,CB] |
| Full Idea: Given a realist view of dispositions as fully actual, even without manifestations or partners, a purely dispositional account of properties has a degree of plausibility, which is enhanced because properties lack purely qualitative characterisations. | |
| From: C.B. Martin (The Mind in Nature [2008], 06.4) | |
| A reaction: In the end Martin opts for a mixed account, as in Idea 15484, but he gives reasons here for the view which I favour. If he concedes that dispositions may exist without manifestation, they must surely lack qualities. Are they not properties, then? |
| 15479 | Properties endow a ball with qualities, and with powers or dispositions [Martin,CB] |
| Full Idea: Each property endows a ball with a distinctive qualitative character and a distinctive range of powers or dispositionalities. | |
| From: C.B. Martin (The Mind in Nature [2008], 04.6) | |
| A reaction: I think this is the wrong way round. Do properties support powers, or powers support properties? I favour the latter. Properties are much vaguer than powers. Powers generate the required causation and activity. |
| 15488 | Qualities and dispositions are aspects of properties - what it exhibits, and what it does [Martin,CB] |
| Full Idea: For any intrinsic and irreducible property, what is qualitative and what is dispositional are one and the same property considered as what that property exhibits of its nature and what that property is directive and selective for in its manifestation. | |
| From: C.B. Martin (The Mind in Nature [2008], 06.6) | |
| A reaction: This is supposed to support qualities and dispositions as equal partners, but I don't see how 'what a property exhibits' can have any role in fundamental ontology. What it exhibits may be very misleading about its nature. |
| 15469 | Dispositions in action can be destroyed, be recovered, or remain unchanged [Martin,CB] |
| Full Idea: Three forms of dispositionality are illustrated by explosives (which are destroyed by manifestation), being soluble (where the dispositions is lost but recoverable), and being stable (where the disposition is unchanged). | |
| From: C.B. Martin (The Mind in Nature [2008], 02.7) | |
| A reaction: [compressed] Presumably the explosives could be recovered after the explosion, since the original elements are still there, but it would take a while. The retina remains stable by continually changing. There are no simple distinctions! |
| 15467 | Powers depend on circumstances, so can't be given a conditional analysis [Martin,CB] |
| Full Idea: Nobody believes, or ought to believe, that manifestations of powers follow upon the single event mentioned in the antecedent of the conditional independently of the circumstances. | |
| From: C.B. Martin (The Mind in Nature [2008], 02.4) | |
| A reaction: Another way of putting it would be that the behaviour of powers is more ceteris paribus than law. |
| 15466 | 'The wire is live' can't be analysed as a conditional, because a wire can change its powers [Martin,CB] |
| Full Idea: According to the conditional analysis of 'the wire is live', if the wire is touched then it gives off electricity. What ultimately defeats this analysis is the acknowledged possibility of objects gaining or losing powers. | |
| From: C.B. Martin (The Mind in Nature [2008], 02.3) | |
| A reaction: He offers his 'electro-fink' as a counterexample, where touching the wire changes its disposition. The conditional analysis is simple and clearcut, but dispositions in reality are complex and unstable. |
| 15476 | Structural properties involve dispositionality, so cannot be used to explain it [Martin,CB] |
| Full Idea: I take it as obvious that any structural property involves dispositionality and, therefore, cannot be used to 'explain' dispositionality. | |
| From: C.B. Martin (The Mind in Nature [2008], 04.3) | |
| A reaction: I think this is the right way round. The so-called 'categorical' properties seem to be close in nature to the 'structural' properties. |
| 15465 | Structures don't explain dispositions, because they consist of dispositions [Martin,CB] |
| Full Idea: It is self-defeating to try to explain dispositionality in terms of structural states because structural states are themselves dispositional. | |
| From: C.B. Martin (The Mind in Nature [2008], 01.2) | |
| A reaction: No doubt structures have dispositions, but are they entirely dispositional? Might there be 'emergent' dispositions which can only be explained by the structure itself, rather than by the dispositions that make up the structure? |
| 15481 | I favour the idea of a substratum for properties; spacetime seems to be just a bearer of properties [Martin,CB] |
| Full Idea: I favour the old idea of substratum: the haver of properties not itself had as a property. Space-time might itself be the bearer of properties, not itself borne as a property. | |
| From: C.B. Martin (The Mind in Nature [2008], 04.6) | |
| A reaction: A very nice idea. The choice is between saying either that fundamentals like space-time and physical fields are the propertyless bearers of properties, or that they purely consist of properties (so properties are fundamental, not substrata). |
| 15474 | Properly understood, wholes do no more causal work than their parts [Martin,CB] |
| Full Idea: There is no causal work for the whole that is not done by the parts, provided the complex role of the parts is fully appreciated. | |
| From: C.B. Martin (The Mind in Nature [2008], 04.1) | |
| A reaction: It seems like a truth that because some parts are doing particular causal work (e.g. glue), the whole can acquire causal powers that the mereological sum of parts lacks. |
| 15486 | Only abstract things can have specific and full identity specifications [Martin,CB] |
| Full Idea: Abstract entities (as nonspatiotemporal) seem to be the only candidates for specific and full identity specifications. | |
| From: C.B. Martin (The Mind in Nature [2008], 05.2 n1) | |
| A reaction: Martin says that only the 'mad logician' seeks such specifications elsewhere. Some people like persons to have perfect identity. God is a popular candidate too. Can objects have perfect 'macroscopic' identity? |
| 15475 | The concept of 'identity' must allow for some changes in properties or parts [Martin,CB] |
| Full Idea: We must avoid a use of 'identity' that implies that any entity over time must be said to lack continuing identity simply because it has changed properties or has lost, added, or had substituted some parts. | |
| From: C.B. Martin (The Mind in Nature [2008], 04.3) | |
| A reaction: This may the key area where the logical-mathematical type of philosophy comes into contact with the natural-metaphysical type. Imagine Martin's concept of 'identity' in mathematics. π changes to 3.1387... during the calculation! |
| 15472 | It is pointless to say possible worlds are truthmakers, and then deny that possible worlds exist [Martin,CB] |
| Full Idea: To claim that the truthmaker for a counterfactual, for example, is a set of possible worlds, but to deny that these worlds really exist, seems pointless. | |
| From: C.B. Martin (The Mind in Nature [2008], 03.3) | |
| A reaction: Lewis therefore argues that they do exist. Martin argues that possible worlds are not truthmakers. He rests his account of modality on dispositions. I prefer Martin. |
| 8088 | People still say the Hopi have no time concepts, despite Whorf's later denial [Devlin] |
| Full Idea: The Hopi time myth does not appear to have been stopped for a moment by the fact that Whorf himself subsequently wrote that the Hopi language does indeed have words for past, present, and future | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch. 5) | |
| A reaction: Arguments for relativism based on the Hopi seem now to be thoroughly discredited. Sensible people never believed them in the first place. |
| 15492 | Explanations are mind-dependent, theory-laden, and interest-relative [Martin,CB] |
| Full Idea: Explanations are mind-dependent, theory-laden, and interest-relative. | |
| From: C.B. Martin (The Mind in Nature [2008], 10.2) | |
| A reaction: I don't think you can rule out the 'real' explanation, as the one dominant causal predecessor, such as the earthquake producing a tsunami. |
| 15495 | Analogy works, as when we eat food which others seem to be relishing [Martin,CB] |
| Full Idea: The long-derided way of analogy works! Otherwise why, when someone else is relishing a food we have not tried, is it reasonable for us to try it ourselves? | |
| From: C.B. Martin (The Mind in Nature [2008], 12.2) | |
| A reaction: Why wouldn't we rush to eat something an animal was relishing? Nice idea. |
| 15493 | Memory requires abstraction, as reminders of what cannot be fully remembered [Martin,CB] |
| Full Idea: Selectivity and abstraction are required for the development of memory, because reminders and promptings are rarely replicas of what is being remembered. | |
| From: C.B. Martin (The Mind in Nature [2008], 10.3) | |
| A reaction: I take the key idea of mental life to be that of a 'label'. This need not be verbal, so 'conceptual label'. It could be an image, as on a road sign. Labelling is the most indispensable aspect of thought. We label objects, parts, properties and groups. |
| 8073 | How do we parse 'time flies like an arrow' and 'fruit flies like an apple'? [Devlin] |
| Full Idea: How do people identify subject and verb in the sentences "time flies like an arrow" and "fruit flies like an apple"? | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch. 1) | |
| A reaction: A nice illustration of the fact that even if we have an innate syntax mechanism, it won't work without some semantics, and some experience of the environmental context of utterances. |
| 8076 | The distinction between sentences and abstract propositions is crucial in logic [Devlin] |
| Full Idea: The distinction between sentences and the abstract propositions that they express is one of the key ideas of logic. A logical argument consists of propositions, assembled together in a systematic fashion. | |
| From: Keith Devlin (Goodbye Descartes [1997], Ch. 2) | |
| A reaction: He may claim that arguments consist of abstract propositions, but they always get expressed in sentences. However, the whole idea of logical form implies the existence of propositions - there is something which a messy sentence 'really' says. |
| 6005 | Animals are dangerous and nourishing, and can't form contracts of justice [Hermarchus, by Sedley] |
| Full Idea: Hermarchus said that animal killing is justified by considerations of human safety and nourishment and by animals' inability to form contractual relations of justice with us. | |
| From: report of Hermarchus (fragments/reports [c.270 BCE]) by David A. Sedley - Hermarchus | |
| A reaction: Could the last argument be used to justify torturing animals? Or could we eat a human who was too brain-damaged to form contracts? |
| 15485 | Instead of a cause followed by an effect, we have dispositions in reciprocal manifestation [Martin,CB] |
| Full Idea: The two-event cause-and-effect view is easily avoided and replaced by the view of mutual manifestations of reciprocal disposition partners, suggesting a natural contemporaneity. | |
| From: C.B. Martin (The Mind in Nature [2008], 05.1) | |
| A reaction: This view, which I find much more congenial than the traditional one, is explored in the ideas of Mumford and Anjum. |
| 15491 | Causation should be explained in terms of dispositions and manifestations [Martin,CB] |
| Full Idea: Disposition and manifestation are the basic categories by means of which cause and effect are to be explained. | |
| From: C.B. Martin (The Mind in Nature [2008], 07.8) | |
| A reaction: 'Manifestation' sounds a bit subjective. The manifestation evident to us may not indicate what is really going on below the surface. I like his basic picture. |
| 15468 | Causal counterfactuals are just clumsy linguistic attempts to indicate dispositions [Martin,CB] |
| Full Idea: 'Causal' counterfactuals have a place, of course, but only as clumsy and inexact linguistic gestures to dispositions, and they should be kept in that place. | |
| From: C.B. Martin (The Mind in Nature [2008], 02.6) | |
| A reaction: Counterfactuals only seem to give a regularity account of causation, by correlating an effect with a minimal context which will give rise to it. Surely dispositions run deeper than that? |
| 15470 | Causal laws are summaries of powers [Martin,CB] |
| Full Idea: Causal laws are summaries of what entities are capable and incapable of. | |
| From: C.B. Martin (The Mind in Nature [2008], 02.8) | |
| A reaction: That's a pretty good formulation. Personally I favour a Humean analysis, perhaps along Lewis's lines, but on a basis of real powers. This remark of Martin's has got me rethinking. |
| 15482 | We can't think of space-time as empty and propertyless, and it seems to be a substratum [Martin,CB] |
| Full Idea: It makes no sense in ontology or modern physics to think of space-time as empty and propertyless. Space-time nicely fulfils the condition of a substratum. | |
| From: C.B. Martin (The Mind in Nature [2008], 04.6) | |
| A reaction: At the very least, space-time seems to be 'curved', so it had better be something. Time has properties like being transitive. Space-time (or fields) might be a pure bundle of properties (the only pure bundle?), rather than a substratum. |