67 ideas
| 17240 | Definitions are the first step in philosophy [Hobbes] |
| Full Idea: In beginning philosophy, the first beginning is from definitions. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 1.6.15) | |
| A reaction: Note that he doesn't say that definitions are the aim of philosophy, as some analysts might think. |
| 9023 | If you say that a contradiction is true, you change the meaning of 'not', and so change the subject [Quine] |
| Full Idea: Those who regard the conjunction p.not-p as true think they are talking about negation, 'not', but this ceases to be recognisable as negation. The deviant logician's predicament is when he tries to deny the doctrine he only changes the subject. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.6) | |
| A reaction: The charge of 'changing the subject' has become a classic move in modern discussions of non-standard logics. It is an important idea in discussions of arguments, and is found in Kant's account of the Ontological Argument. |
| 17237 | Definitions of things that are caused must express their manner of generation [Hobbes] |
| Full Idea: Definitions of things which may be understood to have some cause, must consist of such names as express the cause or manner of their generation, as when we define a circle to be a figure made by the circumduction of a straight line in a plane etc. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 1.6.13) | |
| A reaction: His account of the circle is based on its mode of construction, which is the preferred account of Euclid, rather than a statement of its pure nature. |
| 17239 | Definition is resolution of names into successive genera, and finally the difference [Hobbes] |
| Full Idea: The definition is nothing but a resolution of the name into its most universal parts; ...definitions of this kind always consist of genus and difference; the former names being all, till the last, general; and the last of all, difference. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 1.6.14) | |
| A reaction: This is basically the scholastic Aristotelian view of definition. Note that Hobbes explicitly denies that the last step of the definition is general in character. |
| 17241 | A defined name should not appear in the definition [Hobbes] |
| Full Idea: A defined name ought not to be repeated in the definition. ...No total can be part of itself. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 1.6.15) |
| 17242 | 'Petitio principii' is reusing the idea to be defined, in disguised words [Hobbes] |
| Full Idea: 'Petitio principii' is when the conclusion to be proved is disguised in other words, and put for the definition or principle from whence it is to be demonstrated. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 1.6.18) |
| 9012 | Talk of 'truth' when sentences are mentioned; it reminds us that reality is the point of sentences [Quine] |
| Full Idea: The truth predicate has its utility in places where we are compelled to mention sentences. It then serves to point through the sentence to the reality; it serves as a reminder that though sentences are mentioned, reality is still the whole point. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.1) | |
| A reaction: A sensible interpretation of the Tarskian account of truth as disquotation. Quine neatly combines a common sense correspondence with a sophisticated logicians view of the role of truth. So what does "I want the truth here" mean? |
| 9011 | Truth is redundant for single sentences; we do better to simply speak the sentence [Quine] |
| Full Idea: Rather than speak of truth, we do better simply to say the sentence and so speak not about language but about the world. Of singly given sentences, the perfect theory of truth is the 'disappearance theory of truth' (Sellars). | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.1) | |
| A reaction: Quine defends truth as the crucial link between language and reality, but only for large groups of sentences. If someone accuses you of lying or being incorrect, you can respond by repeating your sentence in a firmer tone of voice. |
| 9013 | We can eliminate 'or' from our basic theory, by paraphrasing 'p or q' as 'not(not-p and not-q)' [Quine] |
| Full Idea: The construction of 'alternation' (using 'or') is useful in practice, but superfluous in theory. It can be paraphrased using only negation and conjunction. We say that 'p or q' is paraphrased as 'not(not-p and not-q)'. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.2) | |
| A reaction: Quine treats 'not' and 'and' as the axiomatic logical connectives, and builds the others from those, presumably because that is the smallest number he could get it down to. I quite like it, because it seems to mesh with basic thought procedures. |
| 17245 | A part of a part is a part of a whole [Hobbes] |
| Full Idea: A part of a part is a part of a whole. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.07.09) |
| 9020 | My logical grammar has sentences by predication, then negation, conjunction, and existential quantification [Quine] |
| Full Idea: We chose a standard grammar in which the simple sentences are got by predication, and all further sentences are generated from these by negation, conjunction, and existential quantification. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.3) | |
| A reaction: It is interesting that we 'choose' our logic, apparently guided by an imperative to achieve minimal ontology. Of these basic ingredients, negation and predication are the more mysterious, especially the latter. Quine is a bit of an 'ostrich' about that. |
| 9028 | Maybe logical truth reflects reality, but in different ways in different languages [Quine] |
| Full Idea: Perhaps the logical truths owe their truth to certain traits of reality which are reflected in one way by the grammar of our language, in another way by the grammar of another language, and in a third way by the grammar and lexicon of a third language. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.7) | |
| A reaction: This explains Quine's subsequent interest in translation, and the interest of his pupil Davidson in charity, and whether there could actually be rival conceptual schemes. I like the link between logical truths and reality, which follows Russell. |
| 10014 | Quine rejects second-order logic, saying that predicates refer to multiple objects [Quine, by Hodes] |
| Full Idea: Quine is unwilling to suppose second-order logic intelligible. He holds to Mill's account of the referential role of a predicate: it multiply denotes any and all objects to which it applies, and there is no need for a further 'predicative' entity. | |
| From: report of Willard Quine (Philosophy of Logic [1970]) by Harold Hodes - Logicism and Ontological Commits. of Arithmetic p.130 | |
| A reaction: If we assume that 'quantifying over' something is a commitment to its existence, then I think I am with Quine, because you end up with a massive commitment to universals, which I prefer to avoid. |
| 10828 | Quantifying over predicates is treating them as names of entities [Quine] |
| Full Idea: To put the predicate letter 'F' in a quantifier is to treat predicate position suddenly as name position, and hence to treat predicates as names of entities of some sort. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.5) | |
| A reaction: It is tricky to distinguish quantifying over predicates in a first-order way (by reifying them), and in a second-order way (where it is not clear whether you are quantifying over a property or a unified set of things. |
| 9024 | Excluded middle has three different definitions [Quine] |
| Full Idea: The law of excluded middle, or 'tertium non datur', may be pictured variously as 1) Every closed sentence is true or false; or 2) Every closed sentence or its negation is true; or 3) Every closed sentence is true or not true. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.6) | |
| A reaction: Unlike many top philosophers, Quine thinks clearly about such things. 1) is the classical bivalent reading of excluded middle; 2) is the purely syntactic version; 3) leaves open how we interpret the 'not-true' option. |
| 10012 | Quantification theory can still be proved complete if we add identity [Quine] |
| Full Idea: Complete proof procedures are available not only for quantification theory, but for quantification theory and identity together. Gödel showed that the theory is still complete if we add self-identity and the indiscernability of identicals. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.5) | |
| A reaction: Hence one talks of first-order logic 'with identity', even though, as Quine observes, it is unclear whether identity is actually a logical or a mathematical notion. |
| 9016 | Names are not essential, because naming can be turned into predication [Quine] |
| Full Idea: Names are convenient but redundant, because Fa is equivalent to (an x)(a=x,Fx), so a need only occur in the context a=, but this can be rendered as a simple predicate A, so that Fa gives way to (an x)(Ax.Fx). | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.2) | |
| A reaction: In eliminating names from analysis, Quine takes Russell's strategy a step further. It is probably this which provoked Kripke into going right back to Mill's view of names as basic labels. The name/description boundary is blurred. Mr Gradgrind. |
| 9015 | Universal quantification is widespread, but it is definable in terms of existential quantification [Quine] |
| Full Idea: Universal quantification is prominent in logical practice but superfluous in theory, since (for all x)Fx obviously amounts to not(exists an x)not-Fx. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.2) | |
| A reaction: The equivalence between these two works both ways, some you could take the universal quantifier as primitive instead, which would make general truths prior to particular ones. Is there something deep at stake here? |
| 9025 | You can't base quantification on substituting names for variables, if the irrationals cannot all be named [Quine] |
| Full Idea: A customary argument against quantification based on substitution of names for variables refers to the theorem of set theory that irrational numbers cannot all be assigned integers. Although the integers can all be named, the irrationals therefore can't. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.6) | |
| A reaction: [He names Ruth Marcus as a source of substitutional quantification] This sounds like more than a mere 'argument' against substitutional quantification, but an actual disproof. Or maybe you just can't quantify once you run out of names. |
| 9026 | Some quantifications could be false substitutionally and true objectually, because of nameless objects [Quine] |
| Full Idea: An existential quantification could turn out false when substitutionally construed and true when objectually construed, because of there being objects of the purported kind but only nameless ones. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.6) | |
| A reaction: (Cf. Idea 9025) Some irrational numbers were his candidates for nameless objects, but as decimals they are infinite in length which seems unfair. I don't take even pi or root-2 to be objects in nature, so not naming irrationals doesn't bother me. |
| 10705 | Putting a predicate letter in a quantifier is to make it the name of an entity [Quine] |
| Full Idea: To put the predicate letter 'F' in a quantifier is to treat predicate positions suddenly as name positions, and hence to treat predicates as names of entities of some sort. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.5) | |
| A reaction: Quine's famous objection to second-order logic. But Quine then struggles to give an account of predicates and properties, and hence is accused by Armstrong of being an 'ostrich'. Boolos 1975 also attacks Quine here. |
| 9027 | A sentence is logically true if all sentences with that grammatical structure are true [Quine] |
| Full Idea: A sentence is logically true if all sentences with that grammatical structure are true. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.7) | |
| A reaction: Quine spends some time on the tricky question of deciding which parts of a sentence are grammatical structure ('syncategorematic'), and which parts are what he calls 'lexicon'. I bet there is a Quinean argument which blurs the boundary. |
| 17258 | If we just say one, one, one, one, we don't know where we have got to [Hobbes] |
| Full Idea: By saying one, one, one, one, and so forward, we know not what number we are at beyond two or three. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.12.05) | |
| A reaction: This makes ordinals sound like meta-numbers. |
| 17253 | Change is nothing but movement [Hobbes] |
| Full Idea: All mutation consists in motion only | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.09.06) | |
| A reaction: Another little gem of simplicity from Hobbes, and one with which I am inclined to agree. The value of a variable can 'change', but that may be metaphorical. |
| 16670 | Accidents are just modes of thinking about bodies [Hobbes] |
| Full Idea: An accident is a mode of conceiving a body. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.08.02) | |
| A reaction: In contrast to the other thinkers who followed Suárez on modes in the early 17th century, Hobbes thinks they are just ways of 'conceiving' bodies, rather than actual features of them. |
| 16621 | Accidents are not parts of bodies (like blood in a cloth); they have accidents as things have a size [Hobbes] |
| Full Idea: An accident's being in a body is not to be taken as something contained in that body - as if redness were in blood like blood in a bloody cloth, as part of the whole, for then accident would be a body. It is like body having size or rest or movement. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.08.03) | |
| A reaction: [compressed] Hobbes is fishing for something like the Quinean view of properties, but no one seems to be able to articulate this sceptical view very well. Pasnau says he means to talk of 'the mode of conceiving a body' (De C 8.2). |
| 9017 | Predicates are not names; predicates are the other parties to predication [Quine] |
| Full Idea: Predicates are not names; predicates are the other parties to predication. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.2) | |
| A reaction: Does a wife only exist as party to a marriage? There's something missing here. We are taking predication to be primitive, but we then seem to single out one part of the process - the object - while ignoring the remainder. What are Quinean objects? |
| 16734 | The complete power of an event is just the aggregate of the qualities that produced it [Hobbes] |
| Full Idea: The power of agent and patient taken together, which may be called the complete power, is the same as the complete cause, for each consists in the aggregation together of all the accidents that are required to produce an effect in both agent and patient. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.10.01) | |
| A reaction: They treat powers as macro phenomena, and don't seem to have a sense of the basic powers that build up the big picture. |
| 17247 | The only generalities or universals are names or signs [Hobbes] |
| Full Idea: Nothing is general or universal besides names or signs. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.08.05) | |
| A reaction: This is the perfect motto for nominalists, among which I am inclined to include myself. Hobbes had a fabulous gift for economy of phrasing. This website is dedicated to that ideal. Reality does not contain generalities (obviously!!). |
| 9018 | A physical object is the four-dimensional material content of a portion of space-time [Quine] |
| Full Idea: We might think of a physical object as simply the whole four-dimensional material content, however sporadic and heterogeneous, of some portion of space-time. If it is firm and coherent internally, we call it a body. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.2) | |
| A reaction: An early articulation of one of the two standard views of objects in recent philosophy. I think I prefer the Quinean view, but I am still looking into that one... |
| 14960 | Bodies are independent of thought, and coincide with part of space [Hobbes] |
| Full Idea: A body is that, which having no dependence on our thought, is coincident or coextended with some part of space. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.08.01) | |
| A reaction: This rather Cartesian view doesn't seem to offer any distinction between empty space and space containing an 'object'. Presumably it is the ancestor of the Quinean account just in terms of space-time points. Don't like it. |
| 17250 | If you separate the two places of one thing, you will also separate the thing [Hobbes] |
| Full Idea: One body cannot be in two places at the same time, ...for the place that a body fills being divided into two, the placed body will also be divided into two; the place and the body that fills that place are divided both together. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.08.08) | |
| A reaction: If every time you manipulated one body it affected both of them, you might say that one body was in two places, rather like a mirror image. |
| 17249 | If you separated two things in the same place, you would also separate the places [Hobbes] |
| Full Idea: Two bodies cannot be together in the same place, ..because when a body that fills its whole place is divided into two, the place itself is divided into two also, so that there will be two places. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.08.08) | |
| A reaction: The wonderful things about philosophy is that you are faced with obvious truths of the world, and cannot begin to think why they are true - and then up steps a philosopher and offers you a reason. |
| 17248 | If a whole body is moved, its parts must move with it [Hobbes] |
| Full Idea: How can any whole body be moved, unless all its parts be moved together with it? | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.08.05) | |
| A reaction: This might be a distinguishing mark for a whole physical body. I think it is probably the main mark for ordinary folk. I've never found this idea in Aristotle. |
| 16790 | A body is always the same, whether the parts are together or dispersed [Hobbes] |
| Full Idea: A body is always the same, whether the parts of it be put together or dispersed; or whether it be congealed or dissolved. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.11.07) | |
| A reaction: This appears to be a commitment by Hobbes to what we now call 'classical' mereology - that any bunch of things can count as a whole, whether they are together or dispersed. He seems to mean more than a watch surviving dismantling. |
| 17244 | To make a whole, parts needn't be put together, but can be united in the mind [Hobbes] |
| Full Idea: In composition, it is to be understood that for the making up of a whole there is no need of putting the parts together, so as to make them touch one another, but only of collecting them into one sum in the mind. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.07.08) | |
| A reaction: This seems to the 'unrestricted composition' of classical mereology, since it appears that Hobbes offers no restriction on which parts can be united by a mind, no matter how bizarre. |
| 17233 | Particulars contain universal things [Hobbes] |
| Full Idea: Universal things are contained in the nature of singular things. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 1.6.04) | |
| A reaction: That is the neatest and most accurate summary of the situation I have ever read. Particulars come first, but they are all riddled with generalities (but that is not as well said as Hobbes's remark). |
| 17246 | Some accidental features are permanent, unless the object perishes [Hobbes] |
| Full Idea: There are certain accidents which can never perish except the body perish also. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.08.03) | |
| A reaction: He is just making an observation, and not proposing a theory about essence. |
| 17251 | The feature which picks out or names a thing is usually called its 'essence' [Hobbes] |
| Full Idea: That accident for which we give a certain name to any body, or the accident which denominates its subject, is commonly called the essence thereof. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.08.23) | |
| A reaction: This is clearly a prelude to Locke's more carefully formulated 'nominal essence'. Fairly obvious, for nominalist empiricists. A bit surprising to say this was 'common'. |
| 9019 | Four-d objects helps predication of what no longer exists, and quantification over items from different times [Quine] |
| Full Idea: The four-dimensional view of objects aids relativity, and the grammar of tenses, but in logic it makes sense of applying a predicate to something that no longer exists, or of quantifying over objects that never coexisted at any one time. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.2) | |
| A reaction: Since you can predicate of or quantify over hypothetical or fictional objects ('Hamlet is gloomy', 'phlogiston explained fire quite well', 'peace and quiet would be nice') I don't see the necessity for this bold ontological commitment, on these grounds. |
| 17257 | It is the same river if it has the same source, no matter what flows in it [Hobbes] |
| Full Idea: That will be the same river which flows from one and the same fountain, whether the same water, or other water, or something other than water, flow thence. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.11.07) | |
| A reaction: This makes the source the one necessity for a river. I think the end matters too. If the Thames reversed direction, and flowed into Wales, it would not be the Thames any more. |
| 12853 | Some individuate the ship by unity of matter, and others by unity of form [Hobbes] |
| Full Idea: In the Ship of Theseus, some place individuity in the unity of matter; others, in the unity of form. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.11.07) | |
| A reaction: Simons raises this comment into a dogma, that there are at least two objects present in the ship. If I offered you a sum for the contents of your house, they would have a unity of monetary value. |
| 17256 | If a new ship were made of the discarded planks, would two ships be numerically the same? [Hobbes] |
| Full Idea: If some man kept the old planks as they were taken out, and by putting them afterwards together again in the same order, had again made a ship of them, ...there would have been two ships numerically the same, which is absurd. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.11.07) | |
| A reaction: This is the origin of the famous modern problematical example of the Ship of Theseus. The ancient example is just the case of whether you step into the same river, but using an artefact with parts, to make it clearer. |
| 16794 | As an infant, Socrates was not the same body, but he was the same human being [Hobbes] |
| Full Idea: It makes a great difference to ask concerning Socrates whether he is the same human being or whether he is the same body. For his body, when he is old, cannot be the same it was when he was an infant. …He can, however, be the same human being. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.11.07) | |
| A reaction: This is not commitment to full (Geachian) relative identity, but it notes the problem. |
| 17255 | Two bodies differ when (at some time) you can say something of one you can't say of the other [Hobbes] |
| Full Idea: Two bodies are said to differ from one another, when something may be said of one of them, which cannot be said of the other at the same time. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.11.02) | |
| A reaction: Note the astute addition of 'at the same time'. Note also that it is couched in terms of what is true, rather than in terms of 'properties' or 'accidents'. |
| 9014 | Some conditionals can be explained just by negation and conjunction: not(p and not-q) [Quine] |
| Full Idea: Often the purpose of a conditional, 'if p, q', can be served simply by negation and conjunction: not(p and not-q), the so-called 'material conditional'. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.2) | |
| A reaction: Logicians love the neatness of that, but get into trouble elsewhere with conditionals, particularly over the implications of not-p. |
| 16582 | We can imagine a point swelling and contracting - but not how this could be done [Hobbes] |
| Full Idea: Even if we can feign in our mind that a point swells to a huge bulk and then contracts to a point - imagining something's made from nothing (ex nihilo), and nothing's made from something - still we cannot comprehend how this could be done in nature. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.08.20) | |
| A reaction: [compressed] Pasnau notes that this offers two sorts of conceivability, of something happening, and of a reason for it happening. A really nice idea, significant (I think) for scientific essentialists, who say possibilities are fewer than you think. |
| 17238 | Science aims to show causes and generation of things [Hobbes] |
| Full Idea: The end of science is the demonstration of the causes and generation of things. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 1.6.13) |
| 17260 | Imagination is just weakened sensation [Hobbes] |
| Full Idea: Imagination is nothing else but sense decaying or weakened by the absence of the object. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 4.25.07) | |
| A reaction: This sounds more like memory than imagination. He needs to say something about unusual combinations of memories, I would have thought. |
| 19373 | A 'conatus' is an initial motion, experienced by us as desire or aversion [Hobbes, by Arthur,R] |
| Full Idea: Hobbes' notion of 'conatus' is a 'beginning of motion' - a motion through a point of space in an instant of time. In a human subject this is experience as desire or aversion. It thus forms a bridge between physics and psychology. | |
| From: report of Thomas Hobbes (De Corpore (Elements, First Section) [1655], p.178) by Richard T.W. Arthur - Leibniz 3 'Worlds' | |
| A reaction: This sounds rather like the primitive concept of a power which I like, but the term seems to be used very vaguely, and never discussed carefully. The idea provoked Leibniz to connect physical force with mental life. |
| 2948 | Sensation is merely internal motion of the sentient being [Hobbes] |
| Full Idea: Sense in the sentient, can be nothing else but motion in some of the internal parts of the sentient; and the parts so moved are parts of the organs of sense. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 3.15.02) | |
| A reaction: Amazingly bold for the time, and presumably influenced by Lucretius. I am sympathetic, but to suggest that sensation is nothing more sounds a bit like a category mistake. Has he grasped that the brain is involved? |
| 17261 | Apart from pleasure and pain, the only emotions are appetite and aversion [Hobbes] |
| Full Idea: All the passions, called passions of the mind, consist of appetite and aversion, except pure pleasure and pain. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 4.25.13) | |
| A reaction: He now faces the challenge of explaining all the many other emotions in terms of these two. Good luck with that, Thomas. |
| 17236 | Words are not for communication, but as marks for remembering what we have learned [Hobbes] |
| Full Idea: The use of words consists in this, that they may serve for marks by which whatsoever we have found out may be recalled to memory ...but not as signs by which we declare the same to others. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 1.6.11) | |
| A reaction: This exactly fits the idea of mental files, of which I am a fan. That this is the actual purpose of language is an unusual but interesting view. |
| 9009 | Single words are strongly synonymous if their interchange preserves truth [Quine] |
| Full Idea: We can define, it would seem, a strong synonymy relation for single words by them being interchangeable salva veritate. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.1) | |
| A reaction: This is a first step in Quine's rejection of synonymous sentences. He goes on to raise the problem of renate/cordate. Presumably any two word types can have different connotations, and hence not always be interchangeable - in poetry, for example. |
| 9007 | It makes no sense to say that two sentences express the same proposition [Quine] |
| Full Idea: My objection to propositions is not parsimony, or disapproval of abstract entities, ..but that propositions induce a relation of synonymy or equivalence between sentences (expressing the same proposition), and this makes no objective sense. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.1) | |
| A reaction: Personally I think propositions are unavoidable when you try to connect language to activities of the brain, and also when you consider animal thought. And also when you introspect about your own language processes. Mr Quine, he wrong. |
| 9008 | There is no rule for separating the information from other features of sentences [Quine] |
| Full Idea: There is no evident rule for separating the information from the stylistic or other immaterial features of the sentences. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.1) | |
| A reaction: There is no rule for deciding precisely when night falls, so I don't believe in night. I take a proposition, prima facie, as an answer to the question 'What exactly do you mean by that remark?' How do you extract logical form from sentences? |
| 9010 | We can abandon propositions, and just talk of sentences and equivalence [Quine] |
| Full Idea: Why not just talk of sentences and equivalence and let the propositions go? Propositions have been projected as shadows of sentences, but at best they will give us nothing the sentences will not give. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.1) | |
| A reaction: I don't understand how you decide that two sentences are equivalent. 'There's someone in that wood'; 'yes, there's a person amongst those trees'. Identical truth-conditions. We can formulate a non-linguistic fact about those truth-conditions. |
| 9021 | A good way of explaining an expression is saying what conditions make its contexts true [Quine] |
| Full Idea: A reasonable way of explaining an expression is by saying what conditions make its various contexts true. | |
| From: Willard Quine (Philosophy of Logic [1970], Ch.3) | |
| A reaction: I like the circumspect phrasing of this, which carefully avoids any entities such as 'meanings' or 'truth conditions'. Maybe the whole core of philosophy of language should shift from theories of meaning to just trying to 'explain' sentences. |
| 1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
| Full Idea: Archelaus was the first person to say that the universe is boundless. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 02.Ar.3 |
| 16600 | Prime matter is body considered with mere size and extension, and potential [Hobbes] |
| Full Idea: Prime matter signifies body considered without the consideration of any form or accident except only magnitude or extension, and aptness to receive form and accidents. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.08.24) | |
| A reaction: I take 'considered without' to indicate that he thinks of it as a psychological abstraction, rather than some actual existing thing. |
| 17252 | Acting on a body is either creating or destroying a property in it [Hobbes] |
| Full Idea: A body is said to work upon or act, that is to say, do something to another body, when it either generates or destroys some accident in it. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.09.01) |
| 17254 | An effect needs a sufficient and necessary cause [Hobbes] |
| Full Idea: There can be no effect but from a sufficient and necessary cause. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.10.02) | |
| A reaction: To be compared with Mackie's subtler modern account of this matter. If two different separate causes could lead to the same result, it is hard to see how the cause must be 'necessary' (unless you say they lead to different effects). |
| 17235 | A cause is the complete sum of the features which necessitate the effect [Hobbes] |
| Full Idea: A cause it the sum or aggregate of all such accidents, both in the agents and in the patient, as concur to the producing of the effect propounded; all of which existing together, ti cannot be understood but that the effect existenth without them. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 1.6.10) | |
| A reaction: For most causes we meet, this definition will include gravity and electro-magnetism, so it doesn't help in narrowing things down. Notice that he accepts the necessity, despite his committed empiricism. |
| 17234 | Motion is losing one place and acquiring another [Hobbes] |
| Full Idea: Motion is privation of one place, and the acquisition of another. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 1.6.06) | |
| A reaction: This is basically the 'at-at' theory of motion which empiricists like, because it breaks motion down into atoms of experience. Hobbes needs an ontology which includes 'places'. |
| 17259 | 'Force' is the quantity of movement imposed on something [Hobbes] |
| Full Idea: I define 'force' to be the impetus or quickness of motion multiplied either into itself, or into the magnitude of the movent, by means of which whereof the said movent works more or less upon the body that resists it. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 3.15.02) | |
| A reaction: Not very helpful, perhaps, but it shows a view of force at quite an early date, well before Newton. |
| 17243 | Past times can't exist anywhere, apart from in our memories [Hobbes] |
| Full Idea: When people speak of the times of their predecessors, they do not think after their predecessors are gone that their times can be any where else than in the memory of those that remember. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 2.07.03) |
| 5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |
| Full Idea: Archelaus wrote that life on Earth began in a primeval slime. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Malcolm Schofield - Archelaus | |
| A reaction: This sounds like a fairly clearcut assertion of the production of life by evolution. Darwin's contribution was to propose the mechanism for achieving it. We should honour the name of Archelaus for this idea. |