27 ideas
16539 | A definition of a circle will show what it is, and show its generating principle [Lowe] |
Full Idea: If the definition of a circle is based on 'locus of a point', this tells us what a circle is, and it does so by revealing its generating principle, what it takes for a circle to come into being. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 6) | |
A reaction: Lowe says that real definitions, as essences, do not always have to spell out a 'generating principle', but they do in this case. Another approach would be to try to map dependence relations between truths about circles, and see what is basic. |
16540 | Defining an ellipse by conic sections reveals necessities, but not the essence of an ellipse [Lowe] |
Full Idea: Defining an ellipse in terms of the oblique intersection of a cone and a plane (rather than in terms of the sum of the distance between the foci) gives us a necessary property, but not the essence, because the terms are extrinsic to its nature. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 6) | |
A reaction: [compressed wording] Helpful and illuminating. If you say some figure is what results when one thing intersects another, that doesn't tell you what the result actually is. Geometrical essences may be a bit vague, but they are quite meaningful. |
16548 | An essence is what an entity is, revealed by a real definition; this is not an entity in its own right [Lowe] |
Full Idea: An entity's essence is just what that entity is, revealed by its real definition. This isn't a distinct entity, but either the entity itself, or (my view) no entity at all. ..We should not reify essence, as that leads to an infinite regress of essences. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 6) | |
A reaction: The regress problem is a real one, if we wish to treat an essence as some proper and distinct part of an entity. If it is a mechanism, for example, the presumably a mechanism has an essence. No, it doesn't! Levels of explanation! |
16549 | Simple things like 'red' can be given real ostensive definitions [Lowe] |
Full Idea: Is it true that we cannot say, non-circularly, what red is? We cannot find a complex synonym for it, but I think we can provide red with an ostensive real definition. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 6) | |
A reaction: I'm not quite sure how 'real' this definition would be, if it depends on observers (some of whom may be colourblind). In what sense is this act of ostensions a 'definition'? You must distinguish the colour from the texture or shape. |
15375 | If terms change their designations in different states, they are functions from states to objects [Fitting] |
Full Idea: The common feature of every designating term is that designation may change from state to state - thus it can be formalized by a function from states to objects. | |
From: Melvin Fitting (Intensional Logic [2007], 3) | |
A reaction: Specifying the objects sounds OK, but specifying states sounds rather tough. |
15376 | Intensional logic adds a second type of quantification, over intensional objects, or individual concepts [Fitting] |
Full Idea: To first order modal logic (with quantification over objects) we can add a second kind of quantification, over intensions. An intensional object, or individual concept, will be modelled by a function from states to objects. | |
From: Melvin Fitting (Intensional Logic [2007], 3.3) |
15378 | Awareness logic adds the restriction of an awareness function to epistemic logic [Fitting] |
Full Idea: Awareness logic enriched Hintikka's epistemic models with an awareness function, mapping each state to the set of formulas we are aware of at that state. This reflects some bound on the resources we can bring to bear. | |
From: Melvin Fitting (Intensional Logic [2007], 3.6.1) | |
A reaction: [He cites Fagin and Halpern 1988 for this] |
15379 | Justication logics make explicit the reasons for mathematical truth in proofs [Fitting] |
Full Idea: In justification logics, the logics of knowledge are extended by making reasons explicit. A logic of proof terms was created, with a semantics. In this, mathematical truths are known for explicit reasons, and these provide a measure of complexity. | |
From: Melvin Fitting (Intensional Logic [2007], 3.6.1) |
11026 | Classical logic is deliberately extensional, in order to model mathematics [Fitting] |
Full Idea: Mathematics is typically extensional throughout (we write 3+2=2+3 despite the two terms having different meanings). ..Classical first-order logic is extensional by design since it primarily evolved to model the reasoning of mathematics. | |
From: Melvin Fitting (Intensional Logic [2007], §1) |
11028 | λ-abstraction disambiguates the scope of modal operators [Fitting] |
Full Idea: λ-abstraction can be used to abstract and disambiguate a predicate. De re is [λx◊P(x)](f) - f has the possible-P property - and de dicto is ◊[λxP(x)](f) - possibly f has the P-property. Also applies to □. | |
From: Melvin Fitting (Intensional Logic [2007], §3.3) | |
A reaction: Compare the Barcan formula. Originated with Church in the 1930s, and Carnap 1947, but revived by Stalnaker and Thomason 1968. Because it refers to the predicate, it has a role in intensional versions of logic, especially modal logic. |
3536 | Supervenient properties must have matching base properties [Kim] |
Full Idea: Each supervenient property necessarily has a coextensive property in the base family. | |
From: Jaegwon Kim (Concepts of supervenience [1984], §5) | |
A reaction: This is presumably the minimum requirement for a situation of supervenience. How do you decide which property is the 'base' property? Do we just mean that the base causes the other, but not vice versa? |
16545 | The essence of lumps and statues shows that two objects coincide but are numerically distinct [Lowe] |
Full Idea: It is a metaphysically necessary truth, obtaining in virtue of the essences of such objects (of what a bronze statue and a lump of bronze are) that when it exists a bronze statue coincides with a lump of bronze, which is numerically distinct from it. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 6) | |
A reaction: I think it is nonsense to treat the lump and statue as two objects. It is essential that a statue be made of a lump, and essential that a lump have a shape, so to treat the lump and the shape as two different objects is a failure to grasp the essence. |
16546 | The essence of a bronze statue shows that it could be made of different bronze [Lowe] |
Full Idea: It is a metaphysical possibility, obtaining in virtue of the essences of such objects, that the same bronze statue should coincide with different lumps of bronze at different times. (..they have different persistence conditions). | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 6) | |
A reaction: If the fame of a statue were that it had been made by melting down the shield of Achilles (say), then the bronze it was made of would be its most important feature. Essences are more contextual than Lowe might wish. |
16551 | Grasping an essence is just grasping a real definition [Lowe] |
Full Idea: All that grasping an essence amounts to is understanding a real definition, that is, understanding a special kind of proposition. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 7) | |
A reaction: He refuses to 'reify' an essence, and says it is not an entity, so he seems to think that the definition is the essence, but Aristotle and I take the essence to be what is picked out by the correct definition - not the definition itself. |
16542 | Explanation can't give an account of essence, because it is too multi-faceted [Lowe] |
Full Idea: Explanation is a multifaceted one, with many species (logical, mathematical, causal, teleological, and psychological), ..so it is not a notion fit to be appealed to in order to frame a perspicuous account of essence. That is one species of explanation. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 6) | |
A reaction: This directly attacks the core of my thesis! His parenthetical list does not give types of explanation. If I say this explanation is 'psychological', that says nothing about what explanation is. All of his instances could rest on essences. |
16552 | If we must know some entity to know an essence, we lack a faculty to do that [Lowe] |
Full Idea: If knowledge of essence were by acquaintance of a special kind of entity, we would doubt our ability to grasp the essence of things. For what faculty could be involved in this special kind of acquaintance? | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 7) | |
A reaction: This is Lockean empirical scepticism about essences, but I take the view that sometimes you can be acquainted with an essence, but more often you correctly infer it from you acquaintance - and this is just what scientists do. |
16533 | Logical necessities, based on laws of logic, are a proper sub-class of metaphysical necessities [Lowe] |
Full Idea: If logically necessary truths are consequences of the laws of logic, then I think they are only a proper sub-class of the class of metaphysically necessary truths. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 1) | |
A reaction: The problem for this is unusual and bizarre systems of logic, or systems that contradict one another. This idea is only plausible if you talk about the truths derived from some roughly 'classical' core of logic. 'Tonk' won't do it! |
16531 | 'Metaphysical' necessity is absolute and objective - the strongest kind of necessity [Lowe] |
Full Idea: By 'metaphysical' necessity I mean necessity of the strongest possible kind - absolute necessity - and I take it to be an objective kind of necessity, rather than being something mind-dependent. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 1) | |
A reaction: See Bob Hale for the possibility that 'absolute' and 'metaphysical' necessity might come apart. I think I believe in metaphysical necessity, but I'm uneasy about 'absolute' necessity. That may be discredited by the sceptics. |
16532 | 'Epistemic' necessity is better called 'certainty' [Lowe] |
Full Idea: 'Epistemic' necessity is more properly to be called 'certainty'. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 1) | |
A reaction: Sounds wrong. Surely I can be totally certain of a contingent truth? |
16543 | If an essence implies p, then p is an essential truth, and hence metaphysically necessary [Lowe] |
Full Idea: If we can truly affirm that it is part of the essence of some entity that p is the case, then p is an essential truth and so a metaphysically necessary truth. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 6) | |
A reaction: This feels too quick. He is trying to expound the idea (which I like) that necessity derives from essences, and not vice versa. Is it a metaphysical necessity that there are no moths in my wardrobe, because mothballs have driven them away? Maybe. |
16544 | Metaphysical necessity is either an essential truth, or rests on essential truths [Lowe] |
Full Idea: A metaphysically necessary truth is a truth which is either an essential truth or a truth that obtains in virtue of the essences of two or more distinct things. Hence all metaphysical necessity is grounded in essence. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 6) | |
A reaction: Lowe is endeavouring to give an exposition of the approach advocated by Kit Fine. I divide necessities 'because of' things (such as essences) from necessities 'for' things, such as situations or events. |
16538 | We could give up possible worlds if we based necessity on essences [Lowe] |
Full Idea: If we explicate the notion of metaphysical necessity in terms of the notion of essence, rather than vice versa, this may enable us to dispense with the language of possible worlds as a means of explicating modal statements. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 6) | |
A reaction: This is the approach I favour, though I am not convinced that the two approaches are in competition, since essentialism gives the driving force for necessity, whereas possible worlds map the logic and semantics of it. |
15377 | Definite descriptions pick out different objects in different possible worlds [Fitting] |
Full Idea: Definite descriptions pick out different objects in different possible worlds quite naturally. | |
From: Melvin Fitting (Intensional Logic [2007], 3.4) | |
A reaction: A definite description can pick out the same object in another possible world, or a very similar one, or an object which has almost nothing in common with the others. |
16534 | 'Intuitions' are just unreliable 'hunches'; over centuries intuitions change enormously [Lowe] |
Full Idea: I suspect that 'intuitions' and 'hunches' are pretty much the same thing, and pretty useless as sources of knowledge. …Things that seemed intuitively true to our forebears a century or two ago often by no means seem intuitively true to us now. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 2) | |
A reaction: I don't accept this. Intuitions change a lot over the centuries because the reliable knowledge which informs intuitions has also changed a lot. Arguments and evidence may nail individual truths, but coherence must rest on intuition. |
16535 | A concept is a way of thinking of things or kinds, whether or not they exist [Lowe] |
Full Idea: The nearest I can get to a quick definition is to say that a concept is a way of thinking of some thing or kind of things, whether or not a really existent thing or kind of things. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 2) | |
A reaction: The focus on 'things' seems rather narrow. Are relations things? He makes concepts sound adverbial, so that there is thinking going on, and then we add 'ways' of doing it. Thinking depends on concepts, not concepts on thinking. |
16550 | Direct reference doesn't seem to require that thinkers know what it is they are thinking about [Lowe] |
Full Idea: It may be objected that currently prevailing causal or 'direct' theories of reference precisely deny that a thinker must know what it is the he or she is thinking about in order to be able to think about it. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 7) | |
A reaction: Lowe says that at least sometimes we have to know that we are thinking about, so this account of reference can't be universally true. My solution is to pull identity and essence apart. You only need identity, not essence, for reference. |
16547 | H2O isn't necessary, because different laws of nature might affect how O and H combine [Lowe] |
Full Idea: It is not metaphysically necessary that water is composed of H2O molecules, because the natural laws governing the chemical behaviour of hydrogen and oxygen atoms could have been significantly different, so they might not have composed that substance. | |
From: E.J. Lowe (What is the Source of Knowledge of Modal Truths? [2013], 6) | |
A reaction: I fear this may be incoherent, as science. See Bird on why salt must dissolve in water. There can't (I suspect) be a law which keeps O and H the same, and yet makes them combine differently. |