110 ideas
| 23269 | Philosophy must start from clearly observed facts [Galen] |
| Full Idea: True philosophers concern themselves first and foremost to take clearly observed facts as their point of departure. | |
| From: Galen (The soul's dependence on the body [c.170], Kiv.11.817) | |
| A reaction: I love this one, especially the desire that the facts be 'clearly observed'. That, thank goodness, eliminates quantum mechanics. If you don't love history and the physical sciences, you are not a philosopher. Oh, and reliable gossip. |
| 23248 | Early empiricists said reason was just a useless concept introduced by philosophers [Galen, by Frede,M] |
| Full Idea: The so-called Empiricists in Hellenistic times [as cited by Galen] denied the existence of reason, treating it as a useless theoretical postulate introduced by some philosophers | |
| From: report of Galen (An Outline of Empiricism [c.170], 87.4-9.28ff) by Michael Frede - Intro to 'Rationality in Greek Thought' p.3 | |
| A reaction: I think 'be sensible' is understood by everyone, but 'use your reason' is far from obvious. The main role of reason seems to be as an identifier for human exceptionalism. Animals obviously make good judgements. Frede thinks the empiricists were right. |
| 8721 | An 'impredicative' definition seems circular, because it uses the term being defined [Friend] |
| Full Idea: An 'impredicative' definition is one that uses the terms being defined in order to give the definition; in some way the definition is then circular. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], Glossary) | |
| A reaction: There has been a big controversy in the philosophy of mathematics over these. Shapiro gives the definition of 'village idiot' (which probably mentions 'village') as an example. |
| 8680 | Classical definitions attempt to refer, but intuitionist/constructivist definitions actually create objects [Friend] |
| Full Idea: In classical logic definitions are thought of as revealing our attempts to refer to objects, ...but for intuitionist or constructivist logics, if our definitions do not uniquely characterize an object, we are not entitled to discuss the object. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 2.4) | |
| A reaction: In defining a chess piece we are obviously creating. In defining a 'tree' we are trying to respond to fact, but the borderlines are vague. Philosophical life would be easier if we were allowed a mixture of creation and fact - so let's have that. |
| 3678 | Reductio ad absurdum proves an idea by showing that its denial produces contradiction [Friend] |
| Full Idea: Reductio ad absurdum arguments are ones that start by denying what one wants to prove. We then prove a contradiction from this 'denied' idea and more reasonable ideas in one's theory, showing that we were wrong in denying what we wanted to prove. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 2.3) | |
| A reaction: This is a mathematical definition, which rests on logical contradiction, but in ordinary life (and philosophy) it would be enough to show that denial led to absurdity, rather than actual contradiction. |
| 8705 | Anti-realists see truth as our servant, and epistemically contrained [Friend] |
| Full Idea: For the anti-realist, truth belongs to us, it is our servant, and as such, it must be 'epistemically constrained'. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 5.1) | |
| A reaction: Put as clearly as this, it strikes me as being utterly and spectacularly wrong, a complete failure to grasp the elementary meaning of a concept etc. etc. If we aren't the servants of truth then we jolly we ought to be. Truth is above us. |
| 14713 | Truth in a scenario is the negation in that scenario being a priori incoherent [Chalmers] |
| Full Idea: The epistemic 1-intension for a sentence S is True at a scenario W iff (W and not-S) is a priori incoherent. | |
| From: David J.Chalmers (Epistemic Two-Dimensional Semantics [2004], p.180-4), quoted by Laura Schroeter - Two-Dimensional Semantics | |
| A reaction: See Two-Dimensional Semantics (in 'Language') and Chalmers for the background to this idea. I love the coherence view of justification, but get a bit nervous when people start defining truth in that way. |
| 8713 | In classical/realist logic the connectives are defined by truth-tables [Friend] |
| Full Idea: In the classical or realist view of logic the meaning of abstract symbols for logical connectives is given by the truth-tables for the symbol. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007]) | |
| A reaction: Presumably this is realist because it connects them to 'truth', but only if that involves a fairly 'realist' view of truth. You could, of course, translate 'true' and 'false' in the table to empty (formalist) symbols such a 0 and 1. Logic is electronics. |
| 8708 | Double negation elimination is not valid in intuitionist logic [Friend] |
| Full Idea: In intuitionist logic, if we do not know that we do not know A, it does not follow that we know A, so the inference (and, in general, double negation elimination) is not intuitionistically valid. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 5.2) | |
| A reaction: That inference had better not be valid in any logic! I am unaware of not knowing the birthday of someone I have never heard of. Propositional attitudes such as 'know' are notoriously difficult to explain in formal logic. |
| 8694 | Free logic was developed for fictional or non-existent objects [Friend] |
| Full Idea: Free logic is especially designed to help regiment our reasoning about fictional objects, or nonexistent objects of some sort. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 3.7) | |
| A reaction: This makes it sound marginal, but I wonder whether existential commitment shouldn't be eliminated from all logic. Why do fictional objects need a different logic? What logic should we use for Robin Hood, if we aren't sure whether or not he is real? |
| 8665 | A 'proper subset' of A contains only members of A, but not all of them [Friend] |
| Full Idea: A 'subset' of A is a set containing only members of A, and a 'proper subset' is one that does not contain all the members of A. Note that the empty set is a subset of every set, but it is not a member of every set. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.5) | |
| A reaction: Is it the same empty set in each case? 'No pens' is a subset of 'pens', but is it a subset of 'paper'? Idea 8219 should be borne in mind when discussing such things, though I am not saying I agree with it. |
| 8672 | A 'powerset' is all the subsets of a set [Friend] |
| Full Idea: The 'powerset' of a set is a set made up of all the subsets of a set. For example, the powerset of {3,7,9} is {null, {3}, {7}, {9}, {3,7}, {3,9}, {7,9}, {3,7,9}}. Taking the powerset of an infinite set gets us from one infinite cardinality to the next. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.5) | |
| A reaction: Note that the null (empty) set occurs once, but not in the combinations. I begin to have queasy sympathies with the constructivist view of mathematics at this point, since no one has the time, space or energy to 'take' an infinite powerset. |
| 8677 | Set theory makes a minimum ontological claim, that the empty set exists [Friend] |
| Full Idea: As a realist choice of what is basic in mathematics, set theory is rather clever, because it only makes a very simple ontological claim: that, independent of us, there exists the empty set. The whole hierarchy of finite and infinite sets then follows. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 2.3) | |
| A reaction: Even so, for non-logicians the existence of the empty set is rather counterintuitive. "There was nobody on the road, so I overtook him". See Ideas 7035 and 8322. You might work back to the empty set, but how do you start from it? |
| 8666 | Infinite sets correspond one-to-one with a subset [Friend] |
| Full Idea: Two sets are the same size if they can be placed in one-to-one correspondence. But even numbers have one-to-one correspondence with the natural numbers. So a set is infinite if it has one-one correspondence with a proper subset. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.5) | |
| A reaction: Dedekind's definition. We can match 1 with 2, 2 with 4, 3 with 6, 4 with 8, etc. Logicians seem happy to give as a definition anything which fixes the target uniquely, even if it doesn't give the essence. See Frege on 0 and 1, Ideas 8653/4. |
| 8682 | Major set theories differ in their axioms, and also over the additional axioms of choice and infinity [Friend] |
| Full Idea: Zermelo-Fraenkel and Gödel-Bernays set theory differ over the notions of ordinal construction and over the notion of class, among other things. Then there are optional axioms which can be attached, such as the axiom of choice and the axiom of infinity. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 2.6) | |
| A reaction: This summarises the reasons why we cannot just talk about 'set theory' as if it was a single concept. The philosophical interest I would take to be found in disentangling the ontological commitments of each version. |
| 8709 | The law of excluded middle is syntactic; it just says A or not-A, not whether they are true or false [Friend] |
| Full Idea: The law of excluded middle is purely syntactic: it says for any well-formed formula A, either A or not-A. It is not a semantic law; it does not say that either A is true or A is false. The semantic version (true or false) is the law of bivalence. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 5.2) | |
| A reaction: No wonder these two are confusing, sufficiently so for a lot of professional philosophers to blur the distinction. Presumably the 'or' is exclusive. So A-and-not-A is a contradiction; but how do you explain a contradiction without mentioning truth? |
| 8711 | Intuitionists read the universal quantifier as "we have a procedure for checking every..." [Friend] |
| Full Idea: In the intuitionist version of quantification, the universal quantifier (normally read as "all") is understood as "we have a procedure for checking every" or "we have checked every". | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 5.5) | |
| A reaction: It seems better to describe this as 'verificationist' (or, as Dummett prefers, 'justificationist'). Intuition suggests an ability to 'see' beyond the evidence. It strikes me as bizarre to say that you can't discuss things you can't check. |
| 8675 | Paradoxes can be solved by talking more loosely of 'classes' instead of 'sets' [Friend] |
| Full Idea: The realist meets the Burali-Forti paradox by saying that all the ordinals are a 'class', not a set. A proper class is what we discuss when we say "all" the so-and-sos when they cannot be reached by normal set-construction. Grammar is their only limit. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 2.3) | |
| A reaction: This strategy would be useful for Class Nominalism, which tries to define properties in terms of classes, but gets tangled in paradoxes. But why bother with strict sets if easy-going classes will do just as well? Descartes's Dream: everything is rational. |
| 8674 | The Burali-Forti paradox asks whether the set of all ordinals is itself an ordinal [Friend] |
| Full Idea: The Burali-Forti paradox says that if ordinals are defined by 'gathering' all their predecessors with the empty set, then is the set of all ordinals an ordinal? It is created the same way, so it should be a further member of this 'complete' set! | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 2.3) | |
| A reaction: This is an example (along with Russell's more famous paradox) of the problems that began to appear in set theory in the early twentieth century. See Idea 8675 for a modern solution. |
| 8667 | The 'integers' are the positive and negative natural numbers, plus zero [Friend] |
| Full Idea: The set of 'integers' is all of the negative natural numbers, and zero, together with the positive natural numbers. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.5) | |
| A reaction: Zero always looks like a misfit at this party. Credit and debit explain positive and negative nicely, but what is the difference between having no money, and money being irrelevant? I can be 'broke', but can the North Pole be broke? |
| 8668 | The 'rational' numbers are those representable as fractions [Friend] |
| Full Idea: The 'rational' numbers are all those that can be represented in the form m/n (i.e. as fractions), where m and n are natural numbers different from zero. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.5) | |
| A reaction: Pythagoreans needed numbers to stop there, in order to represent the whole of reality numerically. See irrational numbers for the ensuing disaster. How can a universe with a finite number of particles contain numbers that are not 'rational'? |
| 8670 | A number is 'irrational' if it cannot be represented as a fraction [Friend] |
| Full Idea: A number is 'irrational' just in case it cannot be represented as a fraction. An irrational number has an infinite non-repeating decimal expansion. Famous examples are pi and e. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.5) | |
| A reaction: There must be an infinite number of irrational numbers. You could, for example, take the expansion of pi, and change just one digit to produce a new irrational number, and pi has an infinity of digits to tinker with. |
| 8661 | The natural numbers are primitive, and the ordinals are up one level of abstraction [Friend] |
| Full Idea: The natural numbers are quite primitive, and are what we first learn about. The order of objects (the 'ordinals') is one level of abstraction up from the natural numbers: we impose an order on objects. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.4) | |
| A reaction: Note the talk of 'levels of abstraction'. So is there a first level of abstraction? Dedekind disagrees with Friend (Idea 7524). I would say that natural numbers are abstracted from something, but I'm not sure what. See Structuralism in maths. |
| 8664 | Cardinal numbers answer 'how many?', with the order being irrelevant [Friend] |
| Full Idea: The 'cardinal' numbers answer the question 'How many?'; the order of presentation of the objects being counted as immaterial. Def: the cardinality of a set is the number of members of the set. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.5) | |
| A reaction: If one asks whether cardinals or ordinals are logically prior (see Ideas 7524 and 8661), I am inclined to answer 'neither'. Presenting them as answers to the questions 'how many?' and 'which comes first?' is illuminating. |
| 8671 | The 'real' numbers (rationals and irrationals combined) is the Continuum, which has no gaps [Friend] |
| Full Idea: The set of 'real' numbers, which consists of the rational numbers and the irrational numbers together, represents "the continuum", since it is like a smooth line which has no gaps (unlike the rational numbers, which have the irrationals missing). | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.5) | |
| A reaction: The Continuum is the perfect abstract object, because a series of abstractions has arrived at a vast limit in its nature. It still has dizzying infinities contained within it, and at either end of the line. It makes you feel humble. |
| 8663 | Raising omega to successive powers of omega reveal an infinity of infinities [Friend] |
| Full Idea: After the multiples of omega, we can successively raise omega to powers of omega, and after that is done an infinite number of times we arrive at a new limit ordinal, which is called 'epsilon'. We have an infinite number of infinite ordinals. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.4) | |
| A reaction: When most people are dumbstruck by the idea of a single infinity, Cantor unleashes an infinity of infinities, which must be the highest into the stratosphere of abstract thought that any human being has ever gone. |
| 8662 | The first limit ordinal is omega (greater, but without predecessor), and the second is twice-omega [Friend] |
| Full Idea: The first 'limit ordinal' is called 'omega', which is ordinal because it is greater than other numbers, but it has no immediate predecessor. But it has successors, and after all of those we come to twice-omega, which is the next limit ordinal. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.4) | |
| A reaction: This is the gateway to Cantor's paradise of infinities, which Hilbert loved and defended. Who could resist the pleasure of being totally boggled (like Aristotle) by a concept such as infinity, only to have someone draw a map of it? See 8663 for sequel. |
| 8669 | Between any two rational numbers there is an infinite number of rational numbers [Friend] |
| Full Idea: Since between any two rational numbers there is an infinite number of rational numbers, we could consider that we have infinity in three dimensions: positive numbers, negative numbers, and the 'depth' of infinite numbers between any rational numbers. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 1.5) | |
| A reaction: This is before we even reach Cantor's staggering infinities (Ideas 8662 and 8663), which presumably reside at the outer reaches of all three of these dimensions of infinity. The 'deep' infinities come from fractions with huge denominators. |
| 8676 | Is mathematics based on sets, types, categories, models or topology? [Friend] |
| Full Idea: Successful competing founding disciplines in mathematics include: the various set theories, type theory, category theory, model theory and topology. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 2.3) | |
| A reaction: Or none of the above? Set theories are very popular. Type theory is, apparently, discredited. Shapiro has a version of structuralism based on model theory (which sound promising). Topology is the one that intrigues me... |
| 8678 | Most mathematical theories can be translated into the language of set theory [Friend] |
| Full Idea: Most of mathematics can be faithfully redescribed by classical (realist) set theory. More precisely, we can translate other mathematical theories - such as group theory, analysis, calculus, arithmetic, geometry and so on - into the language of set theory. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 2.3) | |
| A reaction: This is why most mathematicians seem to regard set theory as foundational. We could also translate football matches into the language of atomic physics. |
| 8701 | The number 8 in isolation from the other numbers is of no interest [Friend] |
| Full Idea: There is no interest for the mathematician in studying the number 8 in isolation from the other numbers. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 4.4) | |
| A reaction: This is a crucial and simple point (arising during a discussion of Shapiro's structuralism). Most things are interesting in themselves, as well as for their relationships, but mathematical 'objects' just are relationships. |
| 8702 | In structuralism the number 8 is not quite the same in different structures, only equivalent [Friend] |
| Full Idea: Structuralists give a historical account of why the 'same' number occupies different structures. Numbers are equivalent rather than identical. 8 is the immediate predecessor of 9 in the whole numbers, but in the rationals 9 has no predecessor. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 4.4) | |
| A reaction: I don't become a different person if I move from a detached house to a terraced house. This suggests that 8 can't be entirely defined by its relations, and yet it is hard to see what its intrinsic nature could be, apart from the units which compose it. |
| 8699 | Are structures 'ante rem' (before reality), or are they 'in re' (grounded in physics)? [Friend] |
| Full Idea: Structuralists disagree over whether objects in structures are 'ante rem' (before reality, existing independently of whether the objects exist) or 'in re' (in reality, grounded in the real world, usually in our theories of physics). | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 4.4) | |
| A reaction: Shapiro holds the first view, Hellman and Resnik the second. The first view sounds too platonist and ontologically extravagant; the second sounds too contingent and limited. The correct account is somewhere in abstractions from the real. |
| 8696 | Structuralist says maths concerns concepts about base objects, not base objects themselves [Friend] |
| Full Idea: According to the structuralist, mathematicians study the concepts (objects of study) such as variable, greater, real, add, similar, infinite set, which are one level of abstraction up from prima facie base objects such as numbers, shapes and lines. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 4.1) | |
| A reaction: This still seems to imply an ontology in which numbers, shapes and lines exist. I would have thought you could eliminate the 'base objects', and just say that the concepts are one level of abstraction up from the physical world. |
| 8695 | Structuralism focuses on relations, predicates and functions, with objects being inessential [Friend] |
| Full Idea: Structuralism says we study whole structures: objects together with their predicates, relations that bear between them, and functions that take us from one domain of objects to a range of other objects. The objects can even be eliminated. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 4.1) | |
| A reaction: The unity of object and predicate is a Quinean idea. The idea that objects are inessential is the dramatic move. To me the proposal has very strong intuitive appeal. 'Eight' is meaningless out of context. Ordinality precedes cardinality? Ideas 7524/8661. |
| 8700 | 'In re' structuralism says that the process of abstraction is pattern-spotting [Friend] |
| Full Idea: In the 'in re' version of mathematical structuralism, pattern-spotting is the process of abstraction. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 4.4) | |
| A reaction: This might work for non-mathematical abstraction as well, if we are allowed to spot patterns within sensual experience, and patterns within abstractions. Properties are causal patterns in the world? No - properties cause patterns. |
| 8681 | The big problem for platonists is epistemic: how do we perceive, intuit, know or detect mathematical facts? [Friend] |
| Full Idea: The main philosophical problem with the position of platonism or realism is the epistemic problem: of explaining what perception or intuition consists in; how it is possible that we should accurately detect whatever it is we are realists about. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 2.5) | |
| A reaction: The best bet, I suppose, is that the mind directly perceives concepts just as eyes perceive the physical (see Idea 8679), but it strikes me as implausible. If we have to come up with a special mental faculty for an area of knowledge, we are in trouble. |
| 8712 | Mathematics should be treated as true whenever it is indispensable to our best physical theory [Friend] |
| Full Idea: Central to naturalism about mathematics are 'indispensability arguments', to the effect that some part of mathematics is indispensable to our best physical theory, and therefore we ought to take that part of mathematics to be true. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 6.1) | |
| A reaction: Quine and Putnam hold this view; Field challenges it. It has the odd consequence that the dispensable parts (if they can be identified!) do not need to be treated as true (even though they might follow logically from the dispensable parts!). Wrong! |
| 8716 | Formalism is unconstrained, so cannot indicate importance, or directions for research [Friend] |
| Full Idea: There are not enough constraints in the Formalist view of mathematics, so there is no way to select a direction for trying to develop mathematics. There is no part of mathematics that is more important than another. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 6.6) | |
| A reaction: One might reply that an area of maths could be 'important' if lots of other areas depended on it, and big developments would ripple big changes through the interior of the subject. Formalism does, though, seem to reduce maths to a game. |
| 8706 | Constructivism rejects too much mathematics [Friend] |
| Full Idea: Too much of mathematics is rejected by the constructivist. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 5.1) | |
| A reaction: This was Hilbert's view. This seems to be generally true of verificationism. My favourite example is that legitimate speculations can be labelled as meaningless. |
| 8707 | Intuitionists typically retain bivalence but reject the law of excluded middle [Friend] |
| Full Idea: An intuitionist typically retains bivalence, but rejects the law of excluded middle. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 5.2) | |
| A reaction: The idea would be to say that only T and F are available as truth-values, but failing to be T does not ensure being F, but merely not-T. 'Unproven' is not-T, but may not be F. |
| 2392 | Properties supervene if you can't have one without the other [Chalmers] |
| Full Idea: B-properties supervene on A-properties if no two possible situations are identical with respect to their A-properties while differing in their B-properties. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.1) | |
| A reaction: Personally I would have thought that if this condition is achieved, then we could go on to say B-properties supervene on A because A is causing them. We shouldn't be shy about this. Personally I think the Bs are necessary. |
| 2393 | Logical supervenience is when one set of properties must be accompanied by another set [Chalmers] |
| Full Idea: B-properties logically supervene on A-properties if no two logically possible situations are identical with respect to their A-properties but distinct with respect to their B-properties. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.1) | |
| A reaction: This is the gap into which Chalmers wants to slip zombies. He's wrong. He thinks that because he can imagine Bs without As, that this makes their separation logically possible. No doubt he can imagine a bonfire on the moon. |
| 2394 | Natural supervenience is when one set of properties is always accompanied by another set [Chalmers] |
| Full Idea: B-properties supervene naturally on A-properties if any two naturally possible situations with the same A-properties have the same B-properties. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.1) | |
| A reaction: Since it is hard to imagine a healthy working brain failing to produce consciousness, given the current laws of nature, almost everyone (except extreme dualists) must concede that they are naturally supervenient. I wonder why they are. |
| 2398 | Reduction requires logical supervenience [Chalmers] |
| Full Idea: Reductive explanation requires a logical supervenience relation. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.3) | |
| A reaction: Why can't you say that in another world there are zombies, but in this world the mind is explained by its natural supervenience on the brain (given the current natural laws)? Driving on the left in Britain is explained by current laws. |
| 16048 | Physicalism says in any two physically indiscernible worlds the positive facts are the same [Chalmers, by Bennett,K] |
| Full Idea: Chalmers says that physicalism is true in a world w just in case every positive fact that obtains in w also obtains in any world physically indiscernible from w. | |
| From: report of David J.Chalmers (The Conscious Mind [1996], 2.1) by Karen Bennett - Supervenience | |
| A reaction: [Bennett summarises Chalmers' argument on pp.39-40] Chalmers says negative facts depend on the world's limits, which aren't part of the physical facts of the world. |
| 2401 | All facts are either physical, experiential, laws of nature, second-order final facts, or indexical facts about me [Chalmers] |
| Full Idea: Facts about the world are exhausted by physical facts, conscious experiences, laws of nature, a second-order that's-all fact, and perhaps an indexical fact about my location. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.5) |
| 8704 | Structuralists call a mathematical 'object' simply a 'place in a structure' [Friend] |
| Full Idea: What the mathematician labels an 'object' in her discipline, is called 'a place in a structure' by the structuralist. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 4.5) | |
| A reaction: This is a strategy for dispersing the idea of an object in the world of thought, parallel to attempts to eliminate them from physical ontology (e.g. Idea 614). |
| 16424 | Strong metaphysical necessity allows fewer possible worlds than logical necessity [Chalmers] |
| Full Idea: The hypothesized modality of 'strong' metaphysical necessity says there are fewer metaphysically possible worlds than there are logically possible worlds, and the a posteriori necessities can stem from factors independent of the semantics of terms. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.4.2) | |
| A reaction: Chalmers sets this up in order to reject it. He notes that it involves a big gap between conceivability and possibility. If a world is logically possible but metaphysically impossible, then it is impossible, surely? |
| 16425 | Metaphysical necessity is a bizarre, brute and inexplicable constraint on possibilities [Chalmers] |
| Full Idea: Strong metaphysical necessities will put constraints on the space of possible worlds that are brute and inexplicable. That's fine for our world, but bizarre for possible worlds. The realm of the possible has no room for such arbitrary constraint. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.4.2) | |
| A reaction: He would say this, given that he wants zombies to be possible, just because he thinks he can conceive of them. Presumably he thinks a raging bonfire with no flames is also possible. His objection here is weak. |
| 16426 | How can we know the metaphysical impossibilities; the a posteriori only concerns this world [Chalmers] |
| Full Idea: If some worlds are metaphysically impossible, it seems that we could never know it. By assumption the information is not available a priori, and a posteriori information only tells us about our world. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.4.2) | |
| A reaction: You need essentialism to reply to this. If you discover the essence of something, you can predict its possibilities. You discover the natures of the powers and dispositions of actuality. |
| 13956 | Kripke is often taken to be challenging a priori insights into necessity [Chalmers] |
| Full Idea: At various points in this book, I use a priori methods to gain insight into necessity; this is the sort of thing that Kripke's account is often taken to challenge. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.4) | |
| A reaction: Chalmers uses his 2-D approach to split off an a priori part from Kripke's a posterior part of our insight into necessity. |
| 13963 | Maybe logical possibility does imply conceivability - by an ideal mind [Chalmers] |
| Full Idea: If we understand conceivability as conceivability-in-principle (by a superbeing?) then it is plausible that logical possibility of a world implies conceivability of the world, so logical possibility of a statement implies its conceivability. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.4) | |
| A reaction: I see nothing incoherent in the possibility that there might be aspects of existence which are utterly inconceivable to any conscious mind. Infinity might be a start, if an 'infinite' mind were impossible. |
| 16473 | Modal Rationalism: conceivability gives a priori access to modal truths [Chalmers, by Stalnaker] |
| Full Idea: Chalmers' 'modal rationalist' is one who identifies what is possible with what is conceivable; the central claim of the doctrine is that we have a priori access to modal truth. | |
| From: report of David J.Chalmers (Does Conceivability Entail Possibility? [2002]) by Robert C. Stalnaker - Mere Possibilities 5 | |
| A reaction: A helpful clarification, as I can now see how hopelessly and utterly wrong Chalmers is (about almost everything), and I find my confidence in any sort of genuine a priori knowledge (except of conceptual relations) dwindling by the minute. |
| 19258 | Evaluate primary possibility from some world, and secondary possibility from this world [Chalmers, by Vaidya] |
| Full Idea: For Chalmers, that water is XYZ is 'primary possible' (a priori, or conceptually), because it is true in some world considered as actual. It is 'secondary impossible', when it is evaluated from the Earth as actual. | |
| From: report of David J.Chalmers (Does Conceivability Entail Possibility? [2002]) by Anand Vaidya - Understanding and Essence Intro | |
| A reaction: [compressed] This is Chalmers' account of how we can know possibility from conceivability, via his two-dimensional semantics (see alphabetical themes). |
| 2407 | One can wrongly imagine two things being non-identical even though they are the same (morning/evening star) [Chalmers] |
| Full Idea: Just because one can imagine that A and B are not identical, it does not follow that A and B are not identical (think of the morning star and the evening star). | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.4.1) |
| 2390 | We attribute beliefs to people in order to explain their behaviour [Chalmers] |
| Full Idea: Belief is something of an explanatory construct: we attribute beliefs to others largely in order to explain their behaviour. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.1.3) |
| 14712 | A sentence is a priori if no possible way the world might actually be could make it false [Chalmers] |
| Full Idea: The Core Thesis for rationalist 2D semantics is that for any sentence S, S is apriori iff S has a necessary 1-intension. (That is, there is no possible way the world might be that, if it actually obtained, would make S false). | |
| From: David J.Chalmers (Epistemic Two-Dimensional Semantics [2004], p.165), quoted by Laura Schroeter - Two-Dimensional Semantics 2.3.2 | |
| A reaction: [The parenthesis is by Schroeter] A '1-intension' is defined by a diagonal on a 2D semantic matrix. Chalmers defends conceivability as the guide to possibility. This is a very traditional view of the a priori, expressed in modern terms. |
| 2397 | 'Perception' means either an action or a mental state [Chalmers] |
| Full Idea: 'Perception' can be used to refer either to the act of perceiving, or the internal state that arises as a result. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.2) |
| 2422 | The structure of the retina has already simplified the colour information which hits it [Chalmers] |
| Full Idea: In vision three varieties of cones abstract out information according to the amount of light present in various overlapping wavelength ranges. Immediately, many distinctions present in the original light wave are lost. | |
| From: David J.Chalmers (The Conscious Mind [1996], 3.8.3) |
| 2396 | Reductive explanation is not the be-all and the end-all of explanation [Chalmers] |
| Full Idea: Reductive explanation is not the be-all and the end-all of explanation. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.2) |
| 23266 | The spirit in the soul wants freedom, power and honour [Galen] |
| Full Idea: The spirited part of the soul is desiderative of freedom, victory, power, authority, reputation, and honour. | |
| From: Galen (The soul's dependence on the body [c.170], Kiv.2.772) | |
| A reaction: This is the concept of 'thumos' [spirit], taken straight from Plato's tripartite account of the soul, in 'Republic'. Note that it includes a desire for freedom (in an age of slavery). |
| 6003 | Galen showed by experiment that the brain controls the body [Galen, by Hankinson] |
| Full Idea: Galen established by experiments in neural anatomy that the brain really is, contra the Stoics and Aristotelians, the body's control centre. | |
| From: report of Galen (On Hippocrates and Plato [c.170]) by R.J. Hankinson - Galen (damaged) | |
| A reaction: And about time too. This is one of the most significant events in the development of human understanding. No one has been able to go back to the old view, even Descartes, no matter how much they may long to do so. |
| 2426 | Why are minds homogeneous and brains fine-grained? [Chalmers] |
| Full Idea: The 'grain problem' for materialism was raised by Sellars: how could an experience be identical with a vast collection of physiological events, given the homogeneity of the former, and the fine-grainedness of the latter? | |
| From: David J.Chalmers (The Conscious Mind [1996], 3.8.5) | |
| A reaction: An interesting question, but it doesn't sound like a huge problem, given the number of connections in the brain. If the brain were expanded (as Leibniz suggested), the 'grains' might start to appear. We can't propose a 'deceived homunculus' to solve it. |
| 23219 | Stopping the heart doesn't terminate activity; pressing the brain does that [Galen, by Cobb] |
| Full Idea: Even when an animals heart was stopped [by hand] it continued its muted whimpers, …but when the brain was pressed the animal stopped making a noise and became unconscious. | |
| From: report of Galen (The soul's dependence on the body [c.170]) by Matthew Cobb - The Idea of the Brain 1 | |
| A reaction: It's not that the ancients didn't do science. It's that ancient people paid no attention to what their scientists discovered. |
| 2391 | Can we be aware but not conscious? [Chalmers] |
| Full Idea: Consciousness is always accompanied by awareness, but awareness as I have described it need not be accompanied by consciousness. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.1.5) | |
| A reaction: One should consult Chalmers, but he is stretching the English word 'awareness' rather far. This road leads to saying that thermostats are 'aware', and information is aware of its content, which is probably very wrong indeed. Compare Idea 2415. |
| 2412 | Can we explain behaviour without consciousness? [Chalmers] |
| Full Idea: However the metaphysics of causation turns out, it seems relatively straightforward that a physical explanation of behaviour can be given that neither appeals to nor implies the existence of consciousness. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.5.2) | |
| A reaction: Chalmers needs this to support his idea that zombies are possible, but it strikes me as implausible. I find it inconceivable that our behaviour would be unchanged if we retained 'awareness' but lost consciousness. Try visiting an art gallery. |
| 2386 | Hard Problem: why brains experience things [Chalmers] |
| Full Idea: The Hard Problem is: why is all this brain processing accompanied by an experienced inner life? | |
| From: David J.Chalmers (The Conscious Mind [1996], Intro) | |
| A reaction: The word 'accompanied' is interesting. A very epiphenomenal word! The answer to this neo-dualist question may be: if you do enough complex representational brain processing at high speed, it adds up to some which we call 'experience'. |
| 2416 | What turns awareness into consciousness? [Chalmers] |
| Full Idea: Given the necessity of awareness, any candidate for an underlying law will have the form "Awareness plus something gives rise to consciousness" (…but simplicity suggests leaving out the 'something'). | |
| From: David J.Chalmers (The Conscious Mind [1996], 3.6.5) | |
| A reaction: You can't leave out the 'something' if you think awareness without consciousness is possible. The phenomenon of blindsight suggests that a whole extra brain area must come into play to produce the consciousness. It may not have a distinct ontology. |
| 2423 | Going down the scale, where would consciousness vanish? [Chalmers] |
| Full Idea: Moving down the scale from lizards to slugs, there doesn't seem much reason to suppose that phenomenology should wink out while a reasonably complex perceptual psychology persists….and if you move on down to thermostats, where would it wink out? | |
| From: David J.Chalmers (The Conscious Mind [1996], 3.8.4) | |
| A reaction: This doesn't seem much of an argument, particularly if its conclusion is that there is phenomenology in thermostats. When day changes into night, where does it 'wink out'? Are we to conclude that night doesn't exist, or that day doesn't exist? |
| 2403 | Nothing in physics even suggests consciousness [Chalmers] |
| Full Idea: Even if we knew every last detail about the physics of the universe, that information would not lead us to postulate the existence of conscious experience. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.3.1.3) | |
| A reaction: I find this a very strange claim. Given that the biggest gap in our physical knowledge is that concerning the brain and consciousness, Chalmer is no position to say this. Why shouldn't a physical revelation suddenly make consciousness inevitable? |
| 2400 | Is intentionality just causal connections? [Chalmers] |
| Full Idea: Intentional properties should be analyzable in terms of causal connections to behaviour and the environment….so there is no separate ontological problem of intentionality. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.5) | |
| A reaction: There could only be no ontological problem if intentional states were purely physical. Everything is made of something (I presume). |
| 2389 | Sometimes we don't notice our pains [Chalmers] |
| Full Idea: What of the fact that we speak of pains that last for a day, even though there are times that they are not conscious? | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.1.3) | |
| A reaction: This is hardly proof that there are non-conscious pains. Otherwise we might say we have a pain even after it has left us for good (because it might return), which seems daft. Not a crucial issue. The word 'pain' has two uses… |
| 2419 | Why should qualia fade during silicon replacement? [Chalmers] |
| Full Idea: If parts of the brain are gradually replaced, perhaps by silicon chips, ...the most reasonable hypothesis is that qualia do not fade at all. | |
| From: David J.Chalmers (The Conscious Mind [1996], 3.7.3) | |
| A reaction: As it stands this could either assert dualism or functionalism. Personally I think the most reasonable hypothesis is that qualia would fade. Chalmers needs more imagination (or less?). What is it like to experience Alzheimer's Disease? |
| 2402 | It seems possible to invert qualia [Chalmers] |
| Full Idea: It seems entirely coherent that experiences could be inverted while physical structure is duplicated exactly. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.3.1.2) | |
| A reaction: Strange how what seems 'entirely coherent' to a leading philosopher strikes me as totally incoherent. I would have thought it was only coherent to a dualist. I don't believe God makes the physics on Thursday, and adds experiences on Friday. |
| 2415 | In blindsight both qualia and intentionality are missing [Chalmers] |
| Full Idea: In blindsight, the information does not qualify as directly available for global control, and subjects are not truly aware of the information. The lack of experience corresponds directly to a lack of awareness. | |
| From: David J.Chalmers (The Conscious Mind [1996], 3.6.3) | |
| A reaction: Blindsight patients give correct answers about objects in their visual field, and you need 'global control' to speak the truth, even if you lack confidence in what you are saying. Philosophers should not be frightened of blindsight. Cf Idea 2391. |
| 21799 | We just use the word 'faculty' when we don't know the psychological cause [Galen] |
| Full Idea: So long as we are ignorant of the true essence of the cause which is operating, we call it a 'faculty'. | |
| From: Galen (On the Natural Faculties [c.170], I.iv), quoted by Dominik Perler - Intro to The Faculties: a History 2 | |
| A reaction: This is probably the view of most modern neuroscientists. I want to defend the idea that we need the concept of a faculty in philosophy, even if the psychologists and neuroscientists say it is too vague for their purposes. |
| 23264 | Philosophers think faculties are in substances, and invent a faculty for every activity [Galen] |
| Full Idea: Philosophers conceive of faculties as things which inhabit 'substances' much as we inhabit houses, not realising that causes of events are conceived in relational terms. We therefore attribute as many faculties to a substance as activities. | |
| From: Galen (The soul's dependence on the body [c.170], Kiv.2.769) | |
| A reaction: This seems to demolish speculative faculties, but they were revived during the Enlightenment. I am happy to talk of 'philosophical faculties' where they are presumed to originate a type of thought, without commitment to any neuroscience. |
| 2414 | When distracted we can totally misjudge our own experiences [Chalmers] |
| Full Idea: If one is distracted one may make judgements about one's experiences that are quite false. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.5.5) | |
| A reaction: Of course, when one is distracted one can make mistakes about anything. This does imply that if there is indeed infallible knowledge to be had from introspection, it will at least require full concentration to achieve it. Cf Idea 8883. |
| 2409 | Maybe dualist interaction is possible at the quantum level? [Chalmers] |
| Full Idea: The only form of interactionist dualism that has seemed even remotely tenable in the contemporary picture is one that exploits certain properties of quantum mechanics. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.4.4) | |
| A reaction: I think he is bluffing. No doubt quantum mechanics offers many intriguing possibilities, such as the interaction of many worlds within the mind, but I am not aware that anything non-physical is ever postulated. Physicists don't deal in the non-physical. |
| 2411 | Supervenience makes interaction laws possible [Chalmers] |
| Full Idea: There is an objection to dualism that it cannot explain how the physical and the nonphysical interact, but the answer is simple on a natural supervenience framework - they interact by virtue of psychophysical laws (…which are as eternal as physics). | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.4.6) | |
| A reaction: There are different sorts of laws. What Chalmers is hoping for would be a mere regularity, like the connection of cancer to smoking, but the objection is that the discovery of causal mechanisms, to give truly explanatory laws, is simply impossible. |
| 2424 | It is odd if experience is a very recent development [Chalmers] |
| Full Idea: It would be odd for a fundamental property like experience to be instantiated for the first time only relatively late in the history of the universe, and even then only in occasional complex systems. | |
| From: David J.Chalmers (The Conscious Mind [1996], 3.8.4) | |
| A reaction: The assumption of this remark is that experience is 'fundamental', which seems to claim that it is a separate ontological category. Maybe, but experience doesn't seem to be a thing. 'Process' seems a better term, and that is not a novelty in the universe. |
| 2413 | If I can have a zombie twin, my own behaviour doesn't need consciousness [Chalmers] |
| Full Idea: The explanation of my zombie twin's claims does not depend on consciousness, as there is none in his world. It follows that the explanation of my claims is also independent of the existence of consciousness. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.5.2) | |
| A reaction: Epiphenomenalism says my accounts of my consciousness are NOT because of my consciousness (which seems daft). Chalmers here gives a very good reason why we should not be a friend of philosophical zombies. |
| 2417 | Does consciousness arise from fine-grained non-reductive functional organisation? [Chalmers] |
| Full Idea: I claim that conscious experience arises from fine-grained functional organisation….. we might call it 'non-reductive functionalism'. | |
| From: David J.Chalmers (The Conscious Mind [1996], 3.7.1) | |
| A reaction: This is Chalmers' final position. If consciousness is 'emergent' and cannot be reduced, what has fine-grained got to do with it? I take 'fine-grained' to be a hint at why the brain becomes conscious. Fine-grained functions cause something. |
| 2428 | Maybe the whole Chinese Room understands Chinese, though the person doesn't [Chalmers] |
| Full Idea: Opponents typically reply to Searle's argument by conceding that the person in the room does not understand Chinese, and arguing that the understanding should instead be attributed to the system consisting of the person and the pieces of paper. | |
| From: David J.Chalmers (The Conscious Mind [1996], 4.9.4) | |
| A reaction: Searle himself spotted this reply. It seems plausible to say that a book contains 'understanding', so the translation dictionary may have it. A good Room would cope with surprise questions. |
| 2418 | The Chinese Mind doesn't seem conscious, but then nor do brains from outside [Chalmers] |
| Full Idea: While it may be intuitively implausible that Block's 'mind' made of the population of China would give rise to conscious experience, it is equally intuitively implausible that a brain should give rise to experience. | |
| From: David J.Chalmers (The Conscious Mind [1996], 3.7.2) | |
| A reaction: This sounds like good support for functionalism, but I am more inclined to see it as a critique of 'intuition' as a route to truth where minds are concerned. Intuition isn't designed for that sort of work. |
| 2406 | H2O causes liquidity, but no one is a dualist about that [Chalmers] |
| Full Idea: Searle argues that H2O causes liquidity, but no one is a dualist about liquidity. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.4.1) | |
| A reaction: Good! |
| 2405 | Perhaps consciousness is physically based, but not logically required by that base [Chalmers] |
| Full Idea: It remains plausible that consciousness arises from a physical basis, even though it is not entailed by that basis. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.4.1) | |
| A reaction: Personally I find this totally implausible. Since every other property or process in the known universe seems to be entailed by its physical basis, I don't expect the mind to be an exception. |
| 2395 | Zombies imply natural but not logical supervenience [Chalmers] |
| Full Idea: It seems logically possible that a creature physically identical to a conscious creature might have no conscious experiences (a zombie)…so conscious experience supervenes naturally but not logically on the physical. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.1) | |
| A reaction: "It seems possible" isn't much of an argument. This claim by Chalmers has been a great incentive to reassess what is or isn't possible. Can a brain lack consciousness? Can a tree fall over silently? Can cyanide stop poisoning us? |
| 9318 | Phenomenal consciousness is fundamental, with no possible nonphenomenal explanation [Chalmers, by Kriegel/Williford] |
| Full Idea: In Chalmers's non-reductive theory, phenomenal consciousness is treated as a fundamental feature of the world, that cannot be explained in nonphenomenal terms. Theory is still possible, in the regularities of interaction. | |
| From: report of David J.Chalmers (The Conscious Mind [1996]) by U Kriegel / K Williford - Intro to 'Self-Representational Consciousness' n2 | |
| A reaction: I can't make much sense of this view without a backing of panpsychism. How could a 'fundamental' feature of reality only begin to appear when life evolves on one particular planet? But 'panpsychism' is a warning of big misunderstandings. See Idea 2424. |
| 2404 | Nothing external shows whether a mouse is conscious [Chalmers] |
| Full Idea: It is consistent with the physical facts about a mouse that it has conscious experiences, and it is consistent with the physical facts that it does not. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.3.1.4) | |
| A reaction: No. It is consistent with our KNOWLEDGE of a mouse that it may or may not be conscious. I take this to be the key error of Chalmers, which led him to the mistaken idea that zombies are possible. The usual confusion of ontology and epistemology…. |
| 23220 | The brain contains memory and reason, and is the source of sensation and decision [Galen] |
| Full Idea: The brain is the principal organ of the psychical members. For within the brain is seated memory, reason and intellect, and from the brain is distributed the power, sensation and voluntary motion. | |
| From: Galen (The soul's dependence on the body [c.170]), quoted by Matthew Cobb - The Idea of the Brain 1 | |
| A reaction: [not sure of ref] Interesting that he assigns the whole of mind to the brain, and not just some aspect of it. He had done experiments. Understanding the role of the brain was amazingly slow. Impeded by religion, I guess. |
| 8685 | Studying biology presumes the laws of chemistry, and it could never contradict them [Friend] |
| Full Idea: In the hierarchy of reduction, when we investigate questions in biology, we have to assume the laws of chemistry but not of economics. We could never find a law of biology that contradicted something in physics or in chemistry. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 3.1) | |
| A reaction: This spells out the idea that there is a direction of dependence between aspects of the world, though we should be cautious of talking about 'levels' (see Idea 7003). We cannot choose the direction in which reduction must go. |
| 2429 | Temperature (etc.) is agreed to be reducible, but it is multiply realisable [Chalmers] |
| Full Idea: Many physical phenomena that are often taken to be paradigms of reducibility (e.g. temperature) are in fact multiply realizable. | |
| From: David J.Chalmers (The Conscious Mind [1996], n 2.20) | |
| A reaction: So multiple realisability isn't such a big problem for physicalism. I take it, though, that all hot things have some physical type of event in common (a level of molecular energy). Finding the level of commonality is the challenge. |
| 23265 | The rational part of the soul is the desire for truth, understanding and recollection [Galen] |
| Full Idea: That part of the soul which we call rational is desiderative: …it desires truth, knowledge, learning, understanding, and recollection - in short, all the good things. | |
| From: Galen (The soul's dependence on the body [c.170], Kiv.2.772) | |
| A reaction: Truth is no surprise, but recollection is. Note the separation of knowledge from understanding. This is a very good characterisation of rationality. For the Greeks it has a moral dimension, of wanting what is good. |
| 18403 | Indexicals may not be objective, but they are a fact about the world as I see it [Chalmers] |
| Full Idea: Even if the indexical is not an objective fact about the world, it is a fact about the world as I find it, and it is the world as I find it that needs explanation. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.5) | |
| A reaction: Chalmers treats them as important, whereas the way he expresses it could make them eliminable, if the world seen by him is eliminable. |
| 8688 | Concepts can be presented extensionally (as objects) or intensionally (as a characterization) [Friend] |
| Full Idea: The extensional presentation of a concept is just a list of the objects falling under the concept. In contrast, an intensional presentation of a concept gives a characterization of the concept, which allows us to pick out which objects fall under it. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 3.4) | |
| A reaction: Logicians seem to favour the extensional view, because (in the standard view) sets are defined simply by their members, so concepts can be explained using sets. I take this to be a mistake. The intensional view seems obviously prior. |
| 14708 | Rationalist 2D semantics posits necessary relations between meaning, apriority, and possibility [Chalmers, by Schroeter] |
| Full Idea: Chalmers seeks a rationalist interpretation of the 2D framework, situated in the tradition which posits a golden triangle of necessary constitutive relations between meaning, apriority, and possibility. | |
| From: report of David J.Chalmers (The Conscious Mind [1996]) by Laura Schroeter - Two-Dimensional Semantics 2.3.1 | |
| A reaction: The first prize of the project is to get some sort of apriori knowledge about these crucial relations. I suppose the superduper prize is to get apriori knowledge of the possibilities of the world, but I wouldn't hold your breath waiting for that. |
| 13958 | The 'primary intension' is non-empirical, and fixes extensions based on the actual-world reference [Chalmers] |
| Full Idea: The 'primary intension' of a concept is a function from worlds to extensions reflecting the way the actual-world reference is fixed, ...which is independent of empirical factors. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.4) | |
| A reaction: This bit is a priori because the concept picks out something, no matter what its essence turns out to be. I take it to be a priori because it is stipulative. |
| 2399 | Meaning has split into primary ("watery stuff"), and secondary counterfactual meaning ("H2O") [Chalmers] |
| Full Idea: The single Fregean intension has fragmented into two: a primary intension ("watery stuff") that fixes reference in the actual world, and a secondary intension ("H2O") that picks out reference in counterfactual possible worlds. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.4) | |
| A reaction: No one actually performs this schizoid double operation, so this is theory disconnected from life. What is the role of 'H2O' in the actual world, and 'watery stuff' in the others? |
| 13959 | The 'secondary intension' is determined by rigidifying (as H2O) the 'water' picked out in the actual world [Chalmers] |
| Full Idea: The 'secondary intension' of 'water' picks out the water (H2O) in all worlds. ..It is determined by first evaluating the primary intension at the actual world, and then rigidifying it so that the same sort of thing is picked out in all possible worlds. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.4) | |
| A reaction: No wonder Soames calls 2-D semantics 'Byzantine'. If we don't actually do this psychologically, what exactly is Chalmers describing? Is this revisionary semantics - i.e. how we ought to do it if we want to talk about the world properly? |
| 13957 | Primary and secondary intensions are the a priori (actual) and a posteriori (counterfactual) aspects of meaning [Chalmers] |
| Full Idea: Primary intension picks out a referent in a world considered as actual; secondary considers it as counterfactual. ...(62) We can think of the primary and secondary intensions as the a priori and a posteriori aspects of meaning, respectively. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.4) | |
| A reaction: Primary intension is a priori because, it seems, it is stipulative ('water' means 'the watery stuff'), whereas the secondary intension (in counterfactual worlds) is empirical ('water' is used to refer to H2O/XYZ). We get internalism and externalism. |
| 13961 | We have 'primary' truth-conditions for the actual world, and derived 'secondary' ones for counterfactual worlds [Chalmers] |
| Full Idea: 'Primary' truth-conditions tell us how the actual world has to be for an utterance of the statement to be true in that world; ....'secondary' truth-conditions give the truth-value in counterfactual worlds, given that the actual world turned out some way. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.4) | |
| A reaction: This is the reinterpretation of the truth-conditions account in terms of two-dimensional semantics. My first reaction is not very positive. Why can't we fix our references in counterfactual worlds, and then apply them to the actual (like inventions)? |
| 14739 | 'Water' is two-dimensionally inconstant, with different intensions in different worlds [Chalmers, by Sider] |
| Full Idea: For Chalmers, 'water' is two-dimensionally inconstant, in that it has different secondary intensions relative to different worlds of utterance. | |
| From: report of David J.Chalmers (Foundations of Two-Dimensional Semantics [2006]) by Theodore Sider - Four Dimensionalism 7.2 | |
| A reaction: In this way 'water' is regarded as being like an indexical (such as 'I'), which has a fixed meaning component, and a second component which varies with different utterances. Maybe. |
| 13962 | Two-dimensional semantics gives a 'primary' and 'secondary' proposition for each statement [Chalmers] |
| Full Idea: If we see a proposition as a function from possible worlds to truth-values, then the two sets of truth-conditions yield two propositions associated with any statement. A 'primary' for those which express a truth, and 'secondary' for counterfactual truth. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.4) | |
| A reaction: This is where 2-D semantics becomes increasingly 'Byzantine'. Intuition and introspection don't seem to offer me two different propositions for every sentence I utter. I can't see this theory catching on, even if it is technically beautiful. |
| 13960 | In two-dimensional semantics we have two aspects to truth in virtue of meaning [Chalmers] |
| Full Idea: Both the 'primary' and 'secondary' intension qualify as truths in virtue of meaning; they are simply true in virtue of different aspects of meaning. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.4) | |
| A reaction: This is the view of two-dimensional semantics, which has split Fregean sense into an a priori and an a posterior part. Chalmers is trying to hang onto the idea that we might see necessity as largely analytic. |
| 7453 | Galen's medicine followed the mean; each illness was balanced by opposite treatment [Galen, by Hacking] |
| Full Idea: Galen ran medicine on the principle of the mean; afflictions must be treated by contraries; hot diseases deserve cold medicine and moist illnesses want drying agents. (Paracelsus rebelled, treating through similarity). | |
| From: report of Galen (On Medical Experience [c.169]) by Ian Hacking - The Emergence of Probability Ch.5 | |
| A reaction: This must be inherited from Aristotle, with the aim of virtue for the body, as Aristotle wanted virtue for the psuché. In some areas Galen is probably right, that natural balance is the aim, as in bodily temperature control. |
| 6030 | Each part of the soul has its virtue - pleasure for appetite, success for competition, and rectitude for reason [Galen] |
| Full Idea: We have by nature these three appropriate relationships, corresponding to each form of the soul's parts - to pleasure because of the appetitive part, to success because of the competitive part, and to rectitude because of the rational part. | |
| From: Galen (On Hippocrates and Plato [c.170], 5.5.8) | |
| A reaction: This is a nice combination of Plato's tripartite theory of soul (in 'Republic') and Aristotle's derivation of virtues from functions. Presumably, though, reason should master the other two, and there is nothing in Galen's idea to explain this. |
| 23268 | We execute irredeemable people, to protect ourselves, as a deterrent, and ending a bad life [Galen] |
| Full Idea: We kill the irredeemably wicked, for three reasons: that they may no longer harm us; as a deterrent to others like them; and because it is actually better from their own point of view to die, when their souls are so damaged they cannot be improved. | |
| From: Galen (The soul's dependence on the body [c.170], Kiv.11.816) | |
| A reaction: The third one sounds like a dubious rationalisation, given that the prisoner probably disagrees. Nowadays we are not so quick to judge someone as irredeemable. The first one works when they run wild, but not after their capture. |
| 16427 | Presumably God can do anything which is logically possible [Chalmers] |
| Full Idea: Presumably it is in God's powers, when creating the world, to do anything that is logically possible. | |
| From: David J.Chalmers (The Conscious Mind [1996], 2.4.2) | |
| A reaction: I don't really understand why anyone would say that the only constraint on God is logic. Presumably no logic is breached if God places in object simultaneously in two spacetime locations, but it would be an impressive achievement. |