57 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. |
| 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) |
| 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) |
| 8729 | Intuitionists deny excluded middle, because it is committed to transcendent truth or objects [Shapiro] |
| Full Idea: Intuitionists in mathematics deny excluded middle, because it is symptomatic of faith in the transcendent existence of mathematical objects and/or the truth of mathematical statements. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 1.2) | |
| A reaction: There are other problems with excluded middle, such as vagueness, but on the whole I, as a card-carrying 'realist', am committed to the law of excluded middle. |
| 8763 | The number 3 is presumably identical as a natural, an integer, a rational, a real, and complex [Shapiro] |
| Full Idea: It is surely wise to identify the positions in the natural numbers structure with their counterparts in the integer, rational, real and complex number structures. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 10.2) | |
| A reaction: The point is that this might be denied, since 3, 3/1, 3.00.., and -3*i^2 are all arrived at by different methods of construction. Natural 3 has a predecessor, but real 3 doesn't. I agree, intuitively, with Shapiro. Russell (1919) disagreed. |
| 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. |
| 18249 | Cauchy gave a formal definition of a converging sequence. [Shapiro] |
| Full Idea: A sequence a1,a2,... of rational numbers is 'Cauchy' if for each rational number ε>0 there is a natural number N such that for all natural numbers m, n, if m>N and n>N then -ε < am - an < ε. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 7.2 n4) | |
| A reaction: The sequence is 'Cauchy' if N exists. |
| 8764 | Categories are the best foundation for mathematics [Shapiro] |
| Full Idea: There is a dedicated contingent who hold that the category of 'categories' is the proper foundation for mathematics. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 10.3 n7) | |
| A reaction: He cites Lawvere (1966) and McLarty (1993), the latter presenting the view as a form of structuralism. I would say that the concept of a category will need further explication, and probably reduce to either sets or relations or properties. |
| 8762 | Two definitions of 3 in terms of sets disagree over whether 1 is a member of 3 [Shapiro] |
| Full Idea: Zermelo said that for each number n, its successor is the singleton of n, so 3 is {{{null}}}, and 1 is not a member of 3. Von Neumann said each number n is the set of numbers less than n, so 3 is {null,{null},{null,{null}}}, and 1 is a member of 3. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 10.2) | |
| A reaction: See Idea 645 - Zermelo could save Plato from the criticisms of Aristotle! These two accounts are cited by opponents of the set-theoretical account of numbers, because it seems impossible to arbitrate between them. |
| 8760 | Numbers do not exist independently; the essence of a number is its relations to other numbers [Shapiro] |
| Full Idea: The structuralist vigorously rejects any sort of ontological independence among the natural numbers; the essence of a natural number is its relations to other natural numbers. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 10.1) | |
| A reaction: This seems to place the emphasis on ordinals (what order?) rather than on cardinality (how many?). I am strongly inclined to think that this is the correct view, though you can't really have relations if there is nothing to relate. |
| 8761 | A 'system' is related objects; a 'pattern' or 'structure' abstracts the pure relations from them [Shapiro] |
| Full Idea: A 'system' is a collection of objects with certain relations among them; a 'pattern' or 'structure' is the abstract form of a system, highlighting the interrelationships and ignoring any features they do not affect how they relate to other objects. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 10.1) | |
| A reaction: Note that 'ignoring' features is a psychological account of abstraction, which (thanks to Frege and Geach) is supposed to be taboo - but which I suspect is actually indispensable in any proper account of thought and concepts. |
| 8744 | Logicism seems to be a non-starter if (as is widely held) logic has no ontology of its own [Shapiro] |
| Full Idea: The thesis that principles of arithmetic are derivable from the laws of logic runs against a now common view that logic itself has no ontology. There are no particular logical objects. From this perspective logicism is a non-starter. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 5.1) | |
| A reaction: This criticism strikes me as utterly devastating. There are two routes to go: prove that logic does have an ontology of objects (what would they be?), or - better - deny that arithmetic contains any 'objects'. Or give up logicism. |
| 8749 | Term Formalism says mathematics is just about symbols - but real numbers have no names [Shapiro] |
| Full Idea: Term Formalism is the view that mathematics is just about characters or symbols - the systems of numerals and other linguistic forms. ...This will cover integers and rational numbers, but what are real numbers supposed to be, if they lack names? | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 6.1.1) | |
| A reaction: Real numbers (such as pi and root-2) have infinite decimal expansions, so we can start naming those. We could also start giving names like 'Harry' to other reals, though it might take a while. OK, I give up. |
| 8750 | Game Formalism is just a matter of rules, like chess - but then why is it useful in science? [Shapiro] |
| Full Idea: Game Formalism likens mathematics to chess, where the 'content' of mathematics is exhausted by the rules of operating with its language. ...This, however, leaves the problem of why the mathematical games are so useful to the sciences. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 6.1.2) | |
| A reaction: This thought pushes us towards structuralism. It could still be a game, but one we learned from observing nature, which plays its own games. Chess is, after all, modelled on warfare. |
| 8752 | Deductivism says mathematics is logical consequences of uninterpreted axioms [Shapiro] |
| Full Idea: The Deductivist version of formalism (sometimes called 'if-thenism') says that the practice of mathematics consists of determining logical consequences of otherwise uninterpreted axioms. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 6.2) | |
| A reaction: [Hilbert is the source] More plausible than Term or Game Formalism (qv). It still leaves the question of why it seems applicable to nature, and why those particular axioms might be chosen. In some sense, though, it is obviously right. |
| 8753 | Critics resent the way intuitionism cripples mathematics, but it allows new important distinctions [Shapiro] |
| Full Idea: Critics commonly complain that the intuitionist restrictions cripple the mathematician. On the other hand, intuitionist mathematics allows for many potentially important distinctions not available in classical mathematics, and is often more subtle. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 7.1) | |
| A reaction: The main way in which it cripples is its restriction on talk of infinity ('Cantor's heaven'), which was resented by Hilbert. Since high-level infinities are interesting, it would be odd if we were not allowed to discuss them. |
| 8731 | Conceptualist are just realists or idealist or nominalists, depending on their view of concepts [Shapiro] |
| Full Idea: I classify conceptualists according to what they say about properties or concepts. If someone classified properties as existing independent of language I would classify her as a realist in ontology of mathematics. Or they may be idealists or nominalists. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 2.2.1) | |
| A reaction: In other words, Shapiro wants to eliminate 'conceptualist' as a useful label in philosophy of mathematics. He's probably right. All thought involves concepts, but that doesn't produce a conceptualist theory of, say, football. |
| 8730 | 'Impredicative' definitions refer to the thing being described [Shapiro] |
| Full Idea: A definition of a mathematical entity is 'impredicative' if it refers to a collection that contains the defined entity. The definition of 'least upper bound' is impredicative as it refers to upper bounds and characterizes a member of this set. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 1.2) | |
| A reaction: The big question is whether mathematics can live with impredicative definitions, or whether they threaten to be viciously circular, and undermine the whole enterprise. |
| 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). |
| 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!!). |
| 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'. |
| 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'. |
| 19378 | Early modern possibility is what occurs sometime; for Leibniz, it is what is not contradictory [Arthur,R] |
| Full Idea: For Descartes, Hobbes and Spinoza, if a state of things is possible, it must occur at some time, whether past, present or future. For Leibniz possibility makes no reference to time; an individual is possible if its concept contains no contradiction. | |
| From: Richard T.W. Arthur (Leibniz [2014], 4 'Contingent') | |
| A reaction: It has always struck me as fallacious to say that anything that is possible must at some time occur. If '6' is possible on the die, what will constrain it to eventually come up when thrown? Mere non-contradiction doesn't imply possibility either. |
| 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. |
| 8725 | Rationalism tries to apply mathematical methodology to all of knowledge [Shapiro] |
| Full Idea: Rationalism is a long-standing school that can be characterized as an attempt to extend the perceived methodology of mathematics to all of knowledge. | |
| From: Stewart Shapiro (Thinking About Mathematics [2000], 1.1) | |
| A reaction: Sometimes called 'Descartes's Dream', or the 'Enlightenment Project', the dream of proving everything. Within maths, Hilbert's Programme aimed for the same certainty. Idea 22 is the motto for the opposition to this approach. |
| 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. |
| 19380 | Occasionalism contradicts the Eucharist, which needs genuine changes of substance [Arthur,R] |
| Full Idea: The Jesuits rejected occasionalism ... because it is incompatible with the Catholic interpretation of the Eucharist, which there is genuine change of substance of the bread into the substance of Christ (transubstantiation). | |
| From: Richard T.W. Arthur (Leibniz [2014], 5 'Substance') | |
| A reaction: Not sure I understand this, but I take it that the Eucharist needs a real relation across the substance-spirit boundary, and not just a co-ordination. |
| 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. |
| 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) |