50 ideas
| 7623 | For ancient Greeks being wise was an ethical value [Putnam] |
| Full Idea: An ancient Greek would have said that being wise is an ethical value. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.6) | |
| A reaction: This is instantly appealing, but since the Enlightenment we are under an obligation to attempt to justify absolutely everything, including the value of wisdom. I'm thinking that it only has value if it leads to eudaimonia. |
| 4714 | Putnam's epistemic notion of truth replaces the realism of correspondence with ontological relativism [Putnam, by O'Grady] |
| Full Idea: Putnam replaces a correspondence theory of truth with an epistemic notion of truth - truth is idealized rational acceptability. The correspondence theory is committed to realism, but his allows ontological relativism. | |
| From: report of Hilary Putnam (Reason, Truth and History [1981]) by Paul O'Grady - Relativism Ch.3 | |
| A reaction: This seems to be part of a slide by Putnam away from realism towards pragmatism. As a robust and defiant realist, this always strikes me as the road to hell. |
| 7617 | Before Kant, all philosophers had a correspondence theory of truth [Putnam] |
| Full Idea: Before Kant it is impossible to find any philosopher who did not have a correspondence theory of truth. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.3) | |
| A reaction: I don't believe this is true of Descartes. See ideas 2266 and 4298. Truth is 'clear and distinct' conceptions, but if you enlarge (and maybe socialise) 'clear' you get coherent. Descartes firmly avoids correspondence, because he can't trust 'facts'. |
| 4716 | The correspondence theory is wrong, because there is no one correspondence between reality and fact [Putnam, by O'Grady] |
| Full Idea: Putnam argues that theory does not correspond to reality, because there are myriad correspondences possible, and we cannot single out "the" relation of correspondence. | |
| From: report of Hilary Putnam (Reason, Truth and History [1981]) by Paul O'Grady - Relativism Ch.3 | |
| A reaction: This obviously depends on views about reference and meaning. I don't see the problem in simple cases, which is all the correspondence theory needs. Complex cases, like chemistry, may well have ambiguities, but so what? |
| 7616 | Truth is an idealisation of rational acceptability [Putnam] |
| Full Idea: Truth is an idealisation of rational acceptability; we speak as if there were such things as epistemically ideal conditions, and we call a statement 'true' if it would be justified under such conditions. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.3) | |
| A reaction: The second part makes human beings sound stupid (which they are not), but the first part is right, and incredibly important. Peirce is behind Putnam's thought. Truth is the target of belief. It isn't a nonsense just because we can't be infallible. |
| 18194 | 'Forcing' can produce new models of ZFC from old models [Maddy] |
| Full Idea: Cohen's method of 'forcing' produces a new model of ZFC from an old model by appending a carefully chosen 'generic' set. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.4) |
| 18195 | A Large Cardinal Axiom would assert ever-increasing stages in the hierarchy [Maddy] |
| Full Idea: A possible axiom is the Large Cardinal Axiom, which asserts that there are more and more stages in the cumulative hierarchy. Infinity can be seen as the first of these stages, and Replacement pushes further in this direction. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.5) |
| 18191 | Axiom of Infinity: completed infinite collections can be treated mathematically [Maddy] |
| Full Idea: The axiom of infinity: that there are infinite sets is to claim that completed infinite collections can be treated mathematically. In its standard contemporary form, the axioms assert the existence of the set of all finite ordinals. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.3) |
| 18193 | The Axiom of Foundation says every set exists at a level in the set hierarchy [Maddy] |
| Full Idea: In the presence of other axioms, the Axiom of Foundation is equivalent to the claim that every set is a member of some Vα. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.3) |
| 18169 | Axiom of Reducibility: propositional functions are extensionally predicative [Maddy] |
| Full Idea: The Axiom of Reducibility states that every propositional function is extensionally equivalent to some predicative proposition function. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.1) |
| 18168 | 'Propositional functions' are propositions with a variable as subject or predicate [Maddy] |
| Full Idea: A 'propositional function' is generated when one of the terms of the proposition is replaced by a variable, as in 'x is wise' or 'Socrates'. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.1) | |
| A reaction: This implies that you can only have a propositional function if it is derived from a complete proposition. Note that the variable can be in either subject or in predicate position. It extends Frege's account of a concept as 'x is F'. |
| 14203 | Intension is not meaning, as 'cube' and 'square-faced polyhedron' are intensionally the same [Putnam] |
| Full Idea: Intension cannot be identified with meaning. ..'Cube' and 'regular polyhedron with six square faces' are logically equivalent predicates. The intension is the same (the function giving the cubes in any possible world) but there is a difference of meaning. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.2) |
| 14207 | If cats equal cherries, model theory allows reinterpretation of the whole language preserving truth [Putnam] |
| Full Idea: If the number of cats happens to equal the cherries, then it follows from the theory of models that there is a reinterpretation of the entire language that leaves all sentences unchanged in truth value while permuting the extensions of 'cat' and 'cherry'. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.2) | |
| A reaction: This horrifying result seems to come simply from the fact that there is an isomorphism between two models, which in turn seems to rest largely on the cardinality of the models. There seems to be something wrong with model theory here (?). |
| 18190 | Completed infinities resulted from giving foundations to calculus [Maddy] |
| Full Idea: The line of development that finally led to a coherent foundation for the calculus also led to the explicit introduction of completed infinities: each real number is identified with an infinite collection of rationals. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.3) | |
| A reaction: Effectively, completed infinities just are the real numbers. |
| 18171 | Cantor and Dedekind brought completed infinities into mathematics [Maddy] |
| Full Idea: Both Cantor's real number (Cauchy sequences of rationals) and Dedekind's cuts involved regarding infinite items (sequences or sets) as completed and subject to further manipulation, bringing the completed infinite into mathematics unambiguously. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.1 n39) | |
| A reaction: So it is the arrival of the real numbers which is the culprit for lumbering us with weird completed infinites, which can then be the subject of addition, multiplication and exponentiation. Maybe this was a silly mistake? |
| 18172 | Infinity has degrees, and large cardinals are the heart of set theory [Maddy] |
| Full Idea: The stunning discovery that infinity comes in different degrees led to the theory of infinite cardinal numbers, the heart of contemporary set theory. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.1) | |
| A reaction: It occurs to me that these huge cardinals only exist in set theory. If you took away that prop, they would vanish in a puff. |
| 18175 | For any cardinal there is always a larger one (so there is no set of all sets) [Maddy] |
| Full Idea: By the mid 1890s Cantor was aware that there could be no set of all sets, as its cardinal number would have to be the largest cardinal number, while his own theorem shows that for any cardinal there is a larger. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.1) | |
| A reaction: There is always a larger cardinal because of the power set axiom. Some people regard that with suspicion. |
| 18196 | An 'inaccessible' cardinal cannot be reached by union sets or power sets [Maddy] |
| Full Idea: An 'inaccessible' cardinal is one that cannot be reached by taking unions of small collections of smaller sets or by taking power sets. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.5) | |
| A reaction: They were introduced by Hausdorff in 1908. |
| 18187 | Theorems about limits could only be proved once the real numbers were understood [Maddy] |
| Full Idea: Even the fundamental theorems about limits could not [at first] be proved because the reals themselves were not well understood. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.2) | |
| A reaction: This refers to the period of about 1850 (Weierstrass) to 1880 (Dedekind and Cantor). |
| 18182 | The extension of concepts is not important to me [Maddy] |
| Full Idea: I attach no decisive importance even to bringing in the extension of the concepts at all. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], §107) | |
| A reaction: He almost seems to equate the concept with its extension, but that seems to raise all sorts of questions, about indeterminate and fluctuating extensions. |
| 18177 | In the ZFC hierarchy it is impossible to form Frege's set of all three-element sets [Maddy] |
| Full Idea: In the ZFC cumulative hierarchy, Frege's candidates for numbers do not exist. For example, new three-element sets are formed at every stage, so there is no stage at which the set of all three-element sets could he formed. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.2) | |
| A reaction: Ah. This is a very important fact indeed if you are trying to understand contemporary discussions in philosophy of mathematics. |
| 18164 | Frege solves the Caesar problem by explicitly defining each number [Maddy] |
| Full Idea: To solve the Julius Caesar problem, Frege requires explicit definitions of the numbers, and he proposes his well-known solution: the number of Fs = the extension of the concept 'equinumerous with F' (based on one-one correspondence). | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.1) | |
| A reaction: Why do there have to be Fs before there can be the corresponding number? If there were no F for 523, would that mean that '523' didn't exist (even if 522 and 524 did exist)? |
| 18184 | Making set theory foundational to mathematics leads to very fruitful axioms [Maddy] |
| Full Idea: The set theory axioms developed in producing foundations for mathematics also have strong consequences for existing fields, and produce a theory that is immensely fruitful in its own right. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.2) | |
| A reaction: [compressed] Second of Maddy's three benefits of set theory. This benefit is more questionable than the first, because the axioms may be invented because of their nice fruit, instead of their accurate account of foundations. |
| 18185 | Unified set theory gives a final court of appeal for mathematics [Maddy] |
| Full Idea: The single unified area of set theory provides a court of final appeal for questions of mathematical existence and proof. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.2) | |
| A reaction: Maddy's third benefit of set theory. 'Existence' means being modellable in sets, and 'proof' means being derivable from the axioms. The slightly ad hoc character of the axioms makes this a weaker defence. |
| 18183 | Set theory brings mathematics into one arena, where interrelations become clearer [Maddy] |
| Full Idea: Set theoretic foundations bring all mathematical objects and structures into one arena, allowing relations and interactions between them to be clearly displayed and investigated. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.2) | |
| A reaction: The first of three benefits of set theory which Maddy lists. The advantages of the one arena seem to be indisputable. |
| 18186 | Identifying geometric points with real numbers revealed the power of set theory [Maddy] |
| Full Idea: The identification of geometric points with real numbers was among the first and most dramatic examples of the power of set theoretic foundations. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.2) | |
| A reaction: Hence the clear definition of the reals by Dedekind and Cantor was the real trigger for launching set theory. |
| 18188 | The line of rationals has gaps, but set theory provided an ordered continuum [Maddy] |
| Full Idea: The structure of a geometric line by rational points left gaps, which were inconsistent with a continuous line. Set theory provided an ordering that contained no gaps. These reals are constructed from rationals, which come from integers and naturals. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.2) | |
| A reaction: This completes the reduction of geometry to arithmetic and algebra, which was launch 250 years earlier by Descartes. |
| 18163 | Mathematics rests on the logic of proofs, and on the set theoretic axioms [Maddy] |
| Full Idea: Our much loved mathematical knowledge rests on two supports: inexorable deductive logic (the stuff of proof), and the set theoretic axioms. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I Intro) |
| 18207 | Maybe applications of continuum mathematics are all idealisations [Maddy] |
| Full Idea: It could turn out that all applications of continuum mathematics in natural sciences are actually instances of idealisation. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], II.6) |
| 18204 | Scientists posit as few entities as possible, but set theorist posit as many as possible [Maddy] |
| Full Idea: Crudely, the scientist posits only those entities without which she cannot account for observations, while the set theorist posits as many entities as she can, short of inconsistency. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], II.5) |
| 18167 | We can get arithmetic directly from HP; Law V was used to get HP from the definition of number [Maddy] |
| Full Idea: Recent commentators have noted that Frege's versions of the basic propositions of arithmetic can be derived from Hume's Principle alone, that the fatal Law V is only needed to derive Hume's Principle itself from the definition of number. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], I.1) | |
| A reaction: Crispin Wright is the famous exponent of this modern view. Apparently Charles Parsons (1965) first floated the idea. |
| 14214 | If we try to cure the abundance of theories with causal links, this is 'just more theory' [Putnam, by Lewis] |
| Full Idea: If we try to base determinate reference on natural causal connection, Putnam says this is just more theory, as subject as any theory to overabundant, conflicting intended interpretations. | |
| From: report of Hilary Putnam (Reason, Truth and History [1981]) by David Lewis - Putnam's Paradox 'Why Are' | |
| A reaction: This is the 1981 Putnam, moving away from the realism that was implicit in the original causal theory of reference developed by himself and Kripke. His 'just more theory' is the slogan of Putnam's later anti-realism. |
| 14205 | The sentence 'A cat is on a mat' remains always true when 'cat' means cherry and 'mat' means tree [Putnam] |
| Full Idea: The sentence 'A cat is on a mat' can be reinterpreted so that in the actual world 'cat' refers to cherries and 'mat' refers to trees, without affecting the truth-value of the sentence in any possible world. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.2) | |
| A reaction: This simple suggestion is the basis of a notorious argument in favour of anti-realism. See D.Lewis's 'Putnam's Paradox'. It tracks back to Skolem's doubts about whether infinitary mathematics is possible. Putnam's conclusion sounds daft. |
| 7610 | A fact is simply what it is rational to accept [Putnam] |
| Full Idea: I propose that the only criterion for what is a fact is what it is rational to accept. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Pref) | |
| A reaction: An epistemological-ontological confusion here. The concept of a fact is of something which is the case quite independently of our criteria for believing it. There are facts which are unknowable for humans. It is, of course, rational to accept facts. |
| 18205 | The theoretical indispensability of atoms did not at first convince scientists that they were real [Maddy] |
| Full Idea: The case of atoms makes it clear that the indispensable appearance of an entity in our best scientific theory is not generally enough to convince scientists that it is real. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], II.6) | |
| A reaction: She refers to the period between Dalton and Einstein, when theories were full of atoms, but there was strong reluctance to actually say that they existed, until the direct evidence was incontrovertable. Nice point. |
| 7618 | Very nominalistic philosophers deny properties, though scientists accept them [Putnam] |
| Full Idea: Some philosophers are so nominalistic that they would deny the existence of such entities as 'properties' altogether; but science itself does not hesitate to talk freely of properties. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.3) | |
| A reaction: Maybe scientists aren't very good at ontology? They talk about forces and energy, but don't seem to know what they are. I am inclined to think that we must include properties in the working ontology of humans, but not into strict physics. |
| 4718 | If necessity is always relative to a description in a language, then there is only 'de dicto' necessity [Putnam, by O'Grady] |
| Full Idea: Putnam endorses the view that necessity is relative to a description, so there is only necessity 'de dicto': relative to language, not to reality. | |
| From: report of Hilary Putnam (Reason, Truth and History [1981]) by Paul O'Grady - Relativism Ch.3 | |
| A reaction: Even a realist must take this proposal seriously. The facts may contain de re necessities, but we could be very sceptical about our capacity to know them. Personally I enjoy speculating about de re necessities. They can't stop you. |
| 21513 | We can no more expect a precise definition of coherence than we can of the moral ideal [Ewing] |
| Full Idea: I think it is wrong to tie down the advocates of the coherence theory to a precise definition. ...It would be altogether unreasonable to demand that the moral ideal should be exhaustively defined, and the same may be true of the ideal of thought. | |
| From: A.C. Ewing (Idealism: a critical survey [1934], p.231), quoted by Erik J. Olsson - Against Coherence 7.6 | |
| A reaction: I strongly agree. It is not a council of despair. I think the criteria of coherence can be articulated quite well (e.g by Thagard), and the virtues of enquiry can also be quite well specified (e.g. by Zagzebski). Very dissimilar evidence must cohere. |
| 21497 | If undetailed, 'coherence' is just a vague words that covers all possible arguments [Ewing] |
| Full Idea: Without a detailed account, coherence is reduced to the mere muttering of the word 'coherence', which can be interpreted so as to cover all arguments, but only by making its meaning so wide as to rob it of almost all significance. | |
| From: A.C. Ewing (Idealism: a critical survey [1934], p.246), quoted by Erik J. Olsson - Against Coherence 2.2 | |
| A reaction: I'm a fan of coherence, but it is a placeholder, involving no intrinsic or detailed theory. I just think it points to the reality of how we make judgements, especially practical ones. We can categorise the inputs, and explain the required virtues. |
| 7620 | Some kind of objective 'rightness' is a presupposition of thought itself [Putnam] |
| Full Idea: What the relativist fails to see is that it is a presupposition of thought itself that some kind of objective 'rightness' exists. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.5) | |
| A reaction: This may be the key objection to relativism. If you have a frame of reference, is it a good one? If you have a new perspective, is it better than your old one? Is the culture you live in confused or clear-thinking? Jokes and metaphors rely on truth. |
| 14204 | Naïve operationalism would have meanings change every time the tests change [Putnam] |
| Full Idea: On a naïve operationalist account every time a new way of testing whether a substance is really gold is discovered, the meaning and reference of 'gold' undergoes a change. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.2) |
| 18206 | Science idealises the earth's surface, the oceans, continuities, and liquids [Maddy] |
| Full Idea: In science we treat the earth's surface as flat, we assume the ocean to be infinitely deep, we use continuous functions for what we know to be quantised, and we take liquids to be continuous despite atomic theory. | |
| From: Penelope Maddy (Naturalism in Mathematics [1997], II.6) | |
| A reaction: If fussy people like scientists do this all the time, how much more so must the confused multitude be doing the same thing all day? |
| 7611 | Rationality is one part of our conception of human flourishing [Putnam] |
| Full Idea: Our notion of rationality is, at bottom, just one part of our conception of human flourishing, our idea of the good. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Pref) | |
| A reaction: This looks like the beginnings of virtue epistemology, since rationality will have criteria, which would seem to be virtues. I find this idea appealing, both as a view of rationality, and as a view of the human good. |
| 14200 | 'Water' on Twin Earth doesn't refer to water, but no mental difference can account for this [Putnam] |
| Full Idea: The word 'water' used on Twin Earth refers not to water but to this other liquid (XYZ). Yet there is no relevant difference in the mental state of Twin Earth speakers and speakers on Earth (in 1750) to account for this difference of reference. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.2) | |
| A reaction: In this world, if you and I separately meet twins, and I think about this twin while you think about that one, our mental states are different even if they are indistinguishable. I know I'm thinking about my twin, not yours. Indexicals. |
| 7612 | Reference is social not individual, because we defer to experts when referring to elm trees [Putnam] |
| Full Idea: My concept of an elm tree is exactly the same as my concept of a beech tree (I blush to confess), which shows that the determination of reference is social and not individual - both you and I defer to experts who can tell elms from beeches. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.1) | |
| A reaction: If I said 'that tree looks nice' I wouldn't be deferring to experts. Nor if I said 'that tree, which I take to be an elm, looks nice'. If I am an expert I don't defer to experts. |
| 7613 | Concepts are (at least in part) abilities and not occurrences [Putnam] |
| Full Idea: Concepts are (at least in part) abilities and not occurrences. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.1) | |
| A reaction: This seems to be building on the idea that meaning is use, and also arises from a background of pragmatism. Perhaps a concept is an acquaintance with a node in platonic space? Lots of abilities aren't concepts, so what distinguishes the concepts? |
| 14202 | Neither individual nor community mental states fix reference [Putnam] |
| Full Idea: Mental state (in either the individualistic or the collective sense) does not fix reference. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.2) | |
| A reaction: The idea that communities fix reference seems to me plausible. See Tyler Burge on this. |
| 14201 | Maybe the total mental state of a language community fixes the reference of a term [Putnam] |
| Full Idea: One might concede that the reference of a person's term isn't fixed by his individual mental state, but insist that the total mental state of all the members of the language community fixes the reference of the term. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.2) | |
| A reaction: I like this reading of the problem, though Putnam himself prefers to say that things fix the reference. I take reference to be a human action, not a natural causal relation. Animals connecting thought to object may not count as reference at all. |
| 14206 | There are infinitely many interpretations of a sentence which can all seem to be 'correct' [Putnam] |
| Full Idea: There are always infinitely many different interpretations of the predicates of a language which assign 'correct' truth-values to the sentences in all possible worlds, no matter how those 'correct' truth-values are singled out. | |
| From: Hilary Putnam (Reason, Truth and History [1981], Ch.2) | |
| A reaction: Putnam says that he is using this argument from model theory to endorse the scepticism about 'gavagai' that Quine expressed in 1960. It is based on the ideas of Skolem, who was a renegade philosopher of mathematics. See Tim Button. |
| 7624 | The word 'inconsiderate' nicely shows the blurring of facts and values [Putnam] |
| Full Idea: The use of the word 'inconsiderate' seems to me a very fine example of the way in which the fact/value distinction is hopelessly fuzzy in the real world and in the real language. | |
| From: Hilary Putnam (Reason, Truth and History [1981]) | |
| A reaction: Interesting, but not much of an argument. What would Nietzsche say? Was Agamemnon morally deficient because we might think him 'inconsiderate'? |