57 ideas
| 4643 | The Principle of Sufficient Reason does not presuppose that all explanations will be causal explanations [Baggini /Fosl] |
| Full Idea: The Principle of Sufficient Reason does not presuppose that all explanations will be causal explanations. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.28) | |
| A reaction: This sounds a reasonable note of caution, but doesn't carry much weight unless some type of non-causal reason can be envisaged. God's free will? Our free will? The laws of causation? |
| 4633 | You cannot rationally deny the principle of non-contradiction, because all reasoning requires it [Baggini /Fosl] |
| Full Idea: Anyone who denies the principle of non-contradiction simultaneously affirms it; it cannot be rationally criticised, because it is presupposed by all rationality. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.12) | |
| A reaction: Nietzsche certainly wasn't afraid to ask why we should reject something because it is a contradiction. The 'logic of personal advantage' might allow logical contradictions. |
| 4635 | Dialectic aims at unified truth, unlike analysis, which divides into parts [Baggini /Fosl] |
| Full Idea: Dialectic can be said to aim at wholeness or unity, while 'analytic' thinking divides that with which it deals into parts. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §2.03) | |
| A reaction: I don't accept this division (linked here to Hegel). I am a fan of analysis, as practised by Aristotle, but it is like dismantling an engine to identify and clean the parts, before reassembling it more efficiently. |
| 4632 | 'Natural' systems of deduction are based on normal rational practice, rather than on axioms [Baggini /Fosl] |
| Full Idea: A 'natural' system of deduction does not posit any axioms, but looks instead for its formulae to the practices of ordinary rationality. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.09) | |
| A reaction: Presumably there is some middle ground, where we attempt to infer the axioms of normal practice, and then build a strict system on them. We must be allowed to criticise 'normal' rationality, I hope. |
| 4631 | In ideal circumstances, an axiom should be such that no rational agent could possibly object to its use [Baggini /Fosl] |
| Full Idea: In ideal circumstances, an axiom should be such that no rational agent could possibly object to its use. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.09) | |
| A reaction: Yes, but the trouble is that all our notions of 'rational' (giving reasons, being consistent) break down when we look at unsupported axioms. In what sense is something rational if it is self-evident? |
| 18395 | Sets are mereological sums of the singletons of their members [Lewis, by Armstrong] |
| Full Idea: Lewis pointed out that many-membered classes are nothing more than the mereological wholes of the classes formed by taking the singleton of each member. | |
| From: report of David Lewis (Parts of Classes [1991]) by David M. Armstrong - Truth and Truthmakers 09.4 | |
| A reaction: You can't combine members to make the class, because the whole and the parts are of different type, but here the parts and whole are both sets, so they combine like waterdrops. |
| 15496 | We can build set theory on singletons: classes are then fusions of subclasses, membership is the singleton [Lewis] |
| Full Idea: The notion of a singleton, or unit set, can serve as the distinctive primitive of set theory. The rest is mereology: a class is the fusion of its singleton subclasses, something is a member of a class iff its singleton is part of that class. | |
| From: David Lewis (Parts of Classes [1991], Pref) | |
| A reaction: This is a gloriously bold proposal which I immediately like, because it cuts out the baffling empty set (which many people think 'exists'!), and gets mathematics back to being about the real world of entities (as the Greeks thought). |
| 15500 | Classes divide into subclasses in many ways, but into members in only one way [Lewis] |
| Full Idea: A class divides exhaustively into subclasses in many different ways; whereas a class divides exhaustively into members in only one way. | |
| From: David Lewis (Parts of Classes [1991], 1.2) |
| 15499 | A subclass of a subclass is itself a subclass; a member of a member is not in general a member [Lewis] |
| Full Idea: Just as a part of a part is itself a part, so a subclass of a subclass is itself a subclass; whereas a member of a member is not in general a member. | |
| From: David Lewis (Parts of Classes [1991], 1.2) | |
| A reaction: Lewis is showing the mereological character of sets, but this is a key distinction in basic set theory. When the members of members are themselves members, the set is said to be 'transitive'. |
| 15503 | We needn't accept this speck of nothingness, this black hole in the fabric of Reality! [Lewis] |
| Full Idea: Must we accept the null set as a most extraordinary individual, a little speck of sheer nothingness, a sort of black hole in the fabric of Reality itself? Not really. | |
| From: David Lewis (Parts of Classes [1991], 1.4) | |
| A reaction: We can only dream of reaching the level of confidence that Lewis reached, to make such beautiful fun of a highly counterintuitive idea that is rooted in the modern techniques of philosophy. |
| 15498 | We can accept the null set, but there is no null class of anything [Lewis] |
| Full Idea: There is no such class as the null class. I don't mind calling some memberless thing - some individual - the null 'set'. But that doesn't make it a memberless class. | |
| From: David Lewis (Parts of Classes [1991], 1.2) | |
| A reaction: The point is that set theory is a formal system which can do what it likes, but classes are classes 'of' things. Everyone assumes that sets are classes, reserving 'proper classes' for the tricky cases up at the far end. |
| 15502 | There are four main reasons for asserting that there is an empty set [Lewis] |
| Full Idea: The null set is a denotation of last resort for class-terms that fail to denote classes, an intersection of x and y where they have no members in common, the class of all self-members, and the real numbers such that x^2+1=0. This is all mere convenience. | |
| From: David Lewis (Parts of Classes [1991], 1.4) | |
| A reaction: A helpful catalogue of main motivations for the existence of the null set in set theory. Lewis aims to undermine these reasons, and dispense with the wretched thing. |
| 15506 | If we don't understand the singleton, then we don't understand classes [Lewis] |
| Full Idea: Our utter ignorance about the nature of the singletons amounts to sheer ignorance about the nature of classes generally. | |
| From: David Lewis (Parts of Classes [1991], 2.1) |
| 15497 | We can replace the membership relation with the member-singleton relation (plus mereology) [Lewis] |
| Full Idea: Given the theory of part and whole, the member-singleton relation may replace membership generally as the primitive notion of set theory. | |
| From: David Lewis (Parts of Classes [1991], Pref) | |
| A reaction: An obvious question is to ask what the member-singleton relation is if it isn't membership. |
| 15511 | If singleton membership is external, why is an object a member of one rather than another? [Lewis] |
| Full Idea: Suppose the relation of member to singleton is external. Why must Possum be a member of one singleton rather than another? Why isn't it contingent which singleton is his? | |
| From: David Lewis (Parts of Classes [1991], 2.2) | |
| A reaction: He cites Van Inwagen for raising this question, and answers it in terms of counterparts. So is the relation internal or external? I think of sets as pairs of curly brackets, not existing entities, so the question doesn't bother me. |
| 15513 | Maybe singletons have a structure, of a thing and a lasso? [Lewis] |
| Full Idea: Maybe the singleton of something x is not an atom, but consists of x plus a lasso. That gives a singleton an internal structure. ...But what do we know of the nature of the lasso, or how it fits? We are no better off. | |
| From: David Lewis (Parts of Classes [1991], 2.5) | |
| A reaction: [second bit on p.45] |
| 15507 | Set theory has some unofficial axioms, generalisations about how to understand it [Lewis] |
| Full Idea: Set theory has its unofficial axioms, traditional remarks about the nature of classes. They are never argued, but are passed heedlessly from one author to another. One of these says that the classes are nowhere: they are outside space and time. | |
| From: David Lewis (Parts of Classes [1991], 2.1) | |
| A reaction: Why don't the people who write formal books on set theory ever say things like this? |
| 10191 | Set theory reduces to a mereological theory with singletons as the only atoms [Lewis, by MacBride] |
| Full Idea: Lewis has shown that set theory may be reduced to a mereological theory in which singletons are the only atoms. | |
| From: report of David Lewis (Parts of Classes [1991]) by Fraser MacBride - Review of Chihara's 'Structural Acc of Maths' p.80 | |
| A reaction: Presumably the axiom of extensionality, that a set is no more than its members, translates into unrestricted composition, that any parts will make an object. Difficult territory, but I suspect that this is of great importance in metaphysics. |
| 15508 | If singletons are where their members are, then so are all sets [Lewis] |
| Full Idea: If every singleton was where its member was, then, in general, classes would be where there members were. | |
| From: David Lewis (Parts of Classes [1991], 2.1) | |
| A reaction: There seems to be a big dislocation of understanding of the nature of sets, between 'pure' set theory, and set theory with ur-elements. I take the pure to be just an 'abstraction' from the more located one. The empty set has a puzzling location. |
| 15514 | A huge part of Reality is only accepted as existing if you have accepted set theory [Lewis] |
| Full Idea: The preponderant part of Reality must consist of unfamiliar, unobserved things, whose existence would have gone unsuspected but for our acceptance of set theory. | |
| From: David Lewis (Parts of Classes [1991], 2.6) | |
| A reaction: He is referring to the enormous sets at the far end of set theory, of a size that had never been hitherto conceived. Excellent. Daft to believe in something entirely because you have accepted set theory, with no other basis. |
| 15523 | Set theory isn't innocent; it generates infinities from a single thing; but mathematics needs it [Lewis] |
| Full Idea: Set theory is not innocent. Its trouble is that when we have one thing, then somehow we have another wholly distinct thing, the singleton. And another, and another....ad infinitum. But that's the price for mathematical power. Pay it. | |
| From: David Lewis (Parts of Classes [1991], 3.6) |
| 4638 | The principle of bivalence distorts reality, as when claiming that a person is or is not 'thin' [Baggini /Fosl] |
| Full Idea: Forcing everything into the straightjacket of bivalence seriously distorts the world. The problem is most acute in the case of vague concepts, such as thinness. It is not straightforwardly true or false that a person is thin. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.03) | |
| A reaction: Can't argue with that. Can we divide all our concepts into either bivalent or vague? Presumably both propositions and concepts could be bivalent. |
| 15525 | Plural quantification lacks a complete axiom system [Lewis] |
| Full Idea: There is an irremediable lack of a complete axiom system for plural quantification. | |
| From: David Lewis (Parts of Classes [1991], 4.7) |
| 15518 | I like plural quantification, but am not convinced of its connection with second-order logic [Lewis] |
| Full Idea: I agree fully with Boolos on substantive questions about plural quantification, though I would make less than he does of the connection with second-order logic. | |
| From: David Lewis (Parts of Classes [1991], 3.2 n2) | |
| A reaction: Deep matters, but my inclination is to agree with Lewis, as I have never been able to see why talk of plural quantification led straight on to second-order logic. A plural is just some objects, not some higher-order entity. |
| 15524 | Zermelo's model of arithmetic is distinctive because it rests on a primitive of set theory [Lewis] |
| Full Idea: What sets Zermelo's modelling of arithmetic apart from von Neumann's and all the rest is that he identifies the primitive of arithmetic with an appropriately primitive notion of set theory. | |
| From: David Lewis (Parts of Classes [1991], 4.6) | |
| A reaction: Zermelo's model is just endlessly nested empty sets, which is a very simple structure. I gather that connoisseurs seem to prefer von Neumann's model (where each number contains its predecessor number). |
| 15517 | Giving up classes means giving up successful mathematics because of dubious philosophy [Lewis] |
| Full Idea: Renouncing classes means rejecting mathematics. That will not do. Mathematics is an established, going concern. Philosophy is as shaky as can be. | |
| From: David Lewis (Parts of Classes [1991], 2.8) | |
| A reaction: This culminates in his famous 'Who's going to tell the mathematicians? Not me!'. He has just given four examples of mathematics that seems to entirely depend on classes. This idea sounds like G.E. Moore's common sense against scepticism. |
| 15515 | To be a structuralist, you quantify over relations [Lewis] |
| Full Idea: To be a structuralist, you quantify over relations. | |
| From: David Lewis (Parts of Classes [1991], 2.6) |
| 15520 | Existence doesn't come in degrees; once asserted, it can't then be qualified [Lewis] |
| Full Idea: Existence cannot be a matter of degree. If you say there is something that exists to a diminished degree, once you've said 'there is' your game is up. | |
| From: David Lewis (Parts of Classes [1991], 3.5) | |
| A reaction: You might have thought that this was so obvious as to be not worth saying, but as far as I can see it is a minority view in contemporary philosophy. It was Quine's view, and it is mine. |
| 15501 | We have no idea of a third sort of thing, that isn't an individual, a class, or their mixture [Lewis] |
| Full Idea: As yet we have no idea of any third sort of thing that is neither individual nor class nor mixture of the two. | |
| From: David Lewis (Parts of Classes [1991], 1.2) | |
| A reaction: You can see that Lewis was a pupil of Quine. I quote this to show how little impression 'stuff' makes on the modern radar. His defence is that stuff may not be a 'thing', but then he seems to think that 'things' exhaust reality (top p.8 and 9). |
| 15504 | Atomless gunk is an individual whose parts all have further proper parts [Lewis] |
| Full Idea: A blob can represent atomless gunk: an individual whose parts all have further proper parts. | |
| From: David Lewis (Parts of Classes [1991], 1.8) | |
| A reaction: This is not the same as 'stuff', since gunk is a precise fusion of all those parts, whereas there is no such precision about stuff. Stuff is neutral as to whether it has atoms, or is endlessly divisible. My love of stuff grows. Laycock is a hero. |
| 15516 | A property is any class of possibilia [Lewis] |
| Full Idea: A property is any class of possibilia. | |
| From: David Lewis (Parts of Classes [1991], 2.7) |
| 14590 | If we accept scattered objects such as archipelagos, why not think of cars that way? [Hawthorne] |
| Full Idea: In being willing to countenance archipelagos, one embraces scattered objects. Why not then embrace the 'archipelago' of my car and the Eiffel Tower? | |
| From: John Hawthorne (Three-Dimensionalism v Four-Dimensionalism [2008], 2.1) | |
| A reaction: This is a beautifully simple and striking point. Language is full of embracing terms like 'the furniture', but that doesn't mean we assume the furniture is unified. The archipelago is less of an 'object' if you live on one of the islands. |
| 14748 | The many are many and the one is one, so they can't be identical [Lewis] |
| Full Idea: What is true of the many is not exactly what is true of the one. After all they are many while it is one. The number of the many is six, whereas the number of the fusion is one. The singletons of the many are distinct from the singleton of the one. | |
| From: David Lewis (Parts of Classes [1991], 3.6) | |
| A reaction: I wouldn't take this objection to be conclusive. 'Some pebbles' seem to be many, but a 'handful of pebbles' seem to be one, where the physical situation might be identical. If they are not identical, then the non-identity is purely conceptual. |
| 6129 | Lewis affirms 'composition as identity' - that an object is no more than its parts [Lewis, by Merricks] |
| Full Idea: Lewis says that the parts of a thing are identical with the whole they compose, calling his view 'composition as identity', which is the claim that a physical object is 'nothing over and above its parts'. | |
| From: report of David Lewis (Parts of Classes [1991], p.84-7) by Trenton Merricks - Objects and Persons §I.IV | |
| A reaction: The ontological economy of this view is obviously attractive, but I don't agree with it. You certainly can't say that all identity consists entirely of composition by parts, because the parts need identity to get the view off the ground. |
| 15512 | In mereology no two things consist of the same atoms [Lewis] |
| Full Idea: It is a principle of mereology that no two things consist of exactly the same atoms. | |
| From: David Lewis (Parts of Classes [1991], 2.3) | |
| A reaction: The problem with this is screamingly obvious - that the same atoms might differ in structure. Lewis did refer to this problem, but seems to try to wriggle out of it, in Idea 15444. |
| 15519 | Trout-turkeys exist, despite lacking cohesion, natural joints and united causal power [Lewis] |
| Full Idea: A trout-turkey is inhomogeneous, disconnected, not in contrast with its surroundings. It is not cohesive, not causally integrated, not a causal unit in its impact on the rest of the world. It is not carved at the joints. That doesn't affect its existence. | |
| From: David Lewis (Parts of Classes [1991], 3.5) | |
| A reaction: A nice pre-emptive strike against all the reasons why anyone might think more is needed for unity than a mereological fusion. |
| 15521 | Given cats, a fusion of cats adds nothing further to reality [Lewis] |
| Full Idea: Given a prior commitment to cats, a commitment to cat-fusions is not a further commitment. The fusion is nothing over and above the cats that compose it. It just is them. They just are it. Together or separately, the cats are the same portion of Reality. | |
| From: David Lewis (Parts of Classes [1991], 3.6) | |
| A reaction: The two extremes of ontology are that there are no objects, or that every combination is an object. Until reading this I thought Lewis was in the second camp, but this sounds like object-nihilism, as in Van Inwagen and Merricks. |
| 15522 | The one has different truths from the many; it is one rather than many, one rather than six [Lewis] |
| Full Idea: What's true of the many is not exactly what's true of the one. After all they are many while it is one. The number of the many is six, whereas the number of the fusion is one. | |
| From: David Lewis (Parts of Classes [1991], 3.6) | |
| A reaction: Together with Idea 15521, this nicely illustrates the gulf between commitment to ontology and commitment to truths. The truths about a fusion change, while its ontology remains the same. Possibly this is the key to all of metaphysics. |
| 14244 | Lewis only uses fusions to create unities, but fusions notoriously flatten our distinctions [Oliver/Smiley on Lewis] |
| Full Idea: Lewis employs mereological fusion as his sole method of making one thing out of many, and fusion is notorious for the way it flattens out and thereby obliterates distinctions. | |
| From: comment on David Lewis (Parts of Classes [1991]) by Oliver,A/Smiley,T - What are Sets and What are they For? 3.1 | |
| A reaction: I take this to be a key point in the discussion of mereology in ontological contexts. As a defender of intrinsic structural essences, I have no use for mereological fusions, and look for a quite different identity for 'wholes'. |
| 10660 | A commitment to cat-fusions is not a further commitment; it is them and they are it [Lewis] |
| Full Idea: Given a prior commitment to cats, a commitment to cat-fusions is not a further commitment. The fusion is nothing over and above the cats that compose it. It just is them. They just are it. | |
| From: David Lewis (Parts of Classes [1991], p.81), quoted by Achille Varzi - Mereology 4.3 | |
| A reaction: I take this to make Lewis a nominalist, saying the same thing that Goodman said about Utah in Idea 10657. Any commitment to cat-fusions being more than the cats, or Utah being more than its counties, strikes me as crazy. |
| 10566 | Lewis prefers giving up singletons to giving up sums [Lewis, by Fine,K] |
| Full Idea: In the face of the conflict between mereology and set theory, Lewis has advocated giving up the existence of singletons rather than sums. | |
| From: report of David Lewis (Parts of Classes [1991]) by Kit Fine - Replies on 'Limits of Abstraction' 1 |
| 14591 | Four-dimensionalists say instantaneous objects are more fundamental than long-lived ones [Hawthorne] |
| Full Idea: Self-proclaimed four-dimensionalists typically adopt a picture that reckons instantaneous objects (and facts about them) to be more fundamental than long-lived ones. | |
| From: John Hawthorne (Three-Dimensionalism v Four-Dimensionalism [2008], 2.2) | |
| A reaction: A nice elucidation. As in Idea 14588, this seems motivated by a desire for some sort of foundationalism or atomism. Why shouldn't a metaphysic treat the middle-sized or temporally extended as foundational, and derive the rest that way? |
| 4640 | If identity is based on 'true of X' instead of 'property of X' we get the Masked Man fallacy ('I know X but not Y') [Baggini /Fosl, by PG] |
| Full Idea: The Masked Man fallacy is when Leibniz's Law is taken as 'X and Y are identical if what is true of X is true of Y' (rather than being about properties). Then 'I know X' but 'I don't know Y' (e.g. my friend wearing a mask) would make X and Y non-identical. | |
| From: report of J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.17) by PG - Db (ideas) | |
| A reaction: As the book goes on to explain, Descartes is guilty of this when arguing that I necessarily know my mind but not my body, so they are different. Seems to me that Kripke falls into the same trap. |
| 4647 | 'I have the same car as you' is fine; 'I have the same fiancée as you' is not so good [Baggini /Fosl] |
| Full Idea: If you found that I had the same car as you, I don't suppose you would care, but if you found I had the same fiancée as you, you might not be so happy. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §4.17) | |
| A reaction: A very nice illustration of the ambiguity of "same", and hence of identity. 'I had the same thought as you'. 'I have the same DNA as you'. |
| 4639 | Leibniz's Law is about the properties of objects; the Identity of Indiscernibles is about perception of objects [Baggini /Fosl] |
| Full Idea: Leibniz's Law ('if identical, must have same properties') defines identity according to the properties possessed by the object itself, but the Identity of Indiscernibles defines identity in terms of how things are conceived or grasped by the mind. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.16) | |
| A reaction: This is the heart of the problem of identity. We realists must fight for Leibniz's Law, and escort the Identity of Indiscernibles to the door. |
| 4646 | Is 'events have causes' analytic a priori, synthetic a posteriori, or synthetic a priori? [Baggini /Fosl] |
| Full Idea: Of the proposition that "all experienced events have causes", Descartes says this is analytic a priori, Hume says it is synthetic a posteriori, and Kant says it is synthetic a priori. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §4.01) | |
| A reaction: I am not sympathetic to Hume on this (though most people think he is right). I prefer the Kantian view, but he makes a very large claim. Something has to be intuitive. |
| 14589 | A modal can reverse meaning if the context is seen differently, so maybe context is all? [Hawthorne] |
| Full Idea: One person says 'He can't dig a hole; he hasn't got a spade', and another says 'He can dig a hole; just give him a spade', and both uses of the modal 'can' will be true. So some philosophers say that all modal predications are thus context-dependent. | |
| From: John Hawthorne (Three-Dimensionalism v Four-Dimensionalism [2008], 1.2) | |
| A reaction: Quine is the guru for this view of modality. Hawthorne's example seems to me to rely too much on the linguistic feature of contrasting 'can' and 'can't'. The underlying assertion in the propositions says something real about the possibilities. |
| 4645 | 'A priori' does not concern how you learn a proposition, but how you show whether it is true or false [Baggini /Fosl] |
| Full Idea: What makes something a priori is not the means by which it came to be known, but the means by which it can be shown to be true or false. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §4.01) | |
| A reaction: Helpful. Kripke in particular has labelled the notion as an epistemological one, but that does imply a method of acquiring it. Clearly I can learn an a priori truth by reading it the newspaper. |
| 15509 | Some say qualities are parts of things - as repeatable universals, or as particulars [Lewis] |
| Full Idea: Some philosophers propose that things have their qualities by having them as parts, either as repeatable universals (Goodman), or as particulars (Donald Williams). | |
| From: David Lewis (Parts of Classes [1991], 2.1 n2) | |
| A reaction: He refers to 'qualities' rather than 'properties', presumably because this view makes them all intrinsic to the object. Is being 'handsome' a part of a person? |
| 4582 | Basic beliefs are self-evident, or sensual, or intuitive, or revealed, or guaranteed [Baggini /Fosl] |
| Full Idea: Sentence are held to be basic because they are self-evident or 'cataleptic' (Stoics), or rooted in sense data (positivists), or grasped by intuition (Platonists), or revealed by God, or grasped by faculties certified by God (Descartes). | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.01) | |
| A reaction: These are a bit blurred. Isn't intuition self-evident? Isn't divine guarantee a type of revelation? How about reason, experience or authority? |
| 4644 | A proposition such as 'some swans are purple' cannot be falsified, only verified [Baggini /Fosl] |
| Full Idea: The problem with falsification is that it fails to work with logically particular claims such as 'some swans are purple'. Examining a million swans and finding no purple ones does not falsify the claim, as there might still be a purple swan out there. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.29) | |
| A reaction: Isn't it beautiful how unease about a theory (Popper's) slowly crystallises into an incredibly simple and devastating point? Maybe 'some swans are purple' isn't science unless there is a good reason to propose it? |
| 4584 | The problem of induction is how to justify our belief in the uniformity of nature [Baggini /Fosl] |
| Full Idea: At its simplest, the problem of induction can be boiled down to the problem of justifying our belief in the uniformity of nature. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.03) | |
| A reaction: An easy solution to the problem of induction: we treat the uniformity of nature as axiomatic, and then induction is all reasoning which is based on that axiom. The axiom is a working hypothesis, which may begin to appear false. Anomalies are hard. |
| 4583 | How can an argument be good induction, but poor deduction? [Baggini /Fosl] |
| Full Idea: The problem of induction is the problem of how an argument can be good reasoning as induction but poor reasoning as deduction. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.03) | |
| A reaction: Nicely put, and a good defence of Hume against the charge that he has just muddled induction and deduction. All reasoning, we insist, should be consistent, or it isn't reasoning. |
| 4634 | Abduction aims at simplicity, testability, coherence and comprehensiveness [Baggini /Fosl] |
| Full Idea: There are some 'principles of selection' in abduction: 1) prefer simple explanations, 2) prefer coherent explanations (consistent with what is already held true), 3) prefer theories that make testable predictions, and 4) be comprehensive in scope. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §2.01) | |
| A reaction: Note that these are desirable, but not necessary (pace Ockham and Ayer). I cannot think of anything to add to the list, so I will adopt it. Abduction is the key to rationality. |
| 4637 | To see if an explanation is the best, it is necessary to investigate the alternative explanations [Baggini /Fosl] |
| Full Idea: The only way to be sure we have the best explanation is to investigate the alternatives and see if they are any better. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.01) | |
| A reaction: Unavoidable! Since I love 'best explanation', I now seem to be committed to investigation every mad theory that comes up, just in case it is better. I hope I am allowed to reject after a very quick sniff. |
| 4629 | Consistency is the cornerstone of rationality [Baggini /Fosl] |
| Full Idea: Consistency is the cornerstone of rationality. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.06) | |
| A reaction: This is right, and is a cornerstone of Kant's approach to ethics. Rational beings must follow principles - in order to be consistent in their behaviour. 'Consistent' now requires a definition…. |
| 14588 | Modern metaphysicians tend to think space-time points are more fundamental than space-time regions [Hawthorne] |
| Full Idea: Nowadays it is common for metaphysicians to hold both that space-time regions are less fundamental than the space-time points that compose them, and that facts about the regions are less fundamental than facts about the points and their arrangements. | |
| From: John Hawthorne (Three-Dimensionalism v Four-Dimensionalism [2008], 1) | |
| A reaction: I'm not quite sure what a physicist would make of this. It seems to be motivated by some a priori preference for atomism, and for system-building from minimal foundations. |