52 ideas
| 19066 | Philosophy aims to understand the world, through ordinary experience and science [Dummett] |
| Full Idea: Philosophy is an attempt to understand the world, as it is revealed to us both in our ordinary experience and by the discoveries and theories of science. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.311) | |
| A reaction: I don't see a sharp division between 'ordinary' and 'scientific'. I really like this idea, first because it makes 'understanding' central, and second because it wants both revelations. In discussing matter and time, there is too much emphasis on science. |
| 8014 | Resolve a complex into simple elements, then reconstruct the complex by using them [Hobbes, by MacIntyre] |
| Full Idea: Hobbes took his method from Galileo, of resolving any complex situation into its logically primitive, simple elements and then using the simple elements to show how the complex situation could be reconstructed. | |
| From: report of Thomas Hobbes (Leviathan [1651]) by Alasdair MacIntyre - A Short History of Ethics Ch.10 | |
| A reaction: Reverse engineering of reality. This idea, wherever it comes from, strikes me as the key to the advance of human understanding. No one has yet improved on it as a method, in science or philosophy. Reconstruction needs the mechanism. |
| 19067 | A successful proof requires recognition of truth at every step [Dummett] |
| Full Idea: For a demonstration to be cogent it is necessary that the passage from step to step involve a recognition of truth at each line. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.313) | |
| A reaction: Dummett cited Quine (esp. 1970) as having an almost entirely syntactic view of logic. Rumfitt points out that logic can move validly from one falsehood to another. Even a 'proof' might detour into falsehood, but it would not be a 'canonical' proof! |
| 19060 | Truth-tables are dubious in some cases, and may be a bad way to explain connective meaning [Dummett] |
| Full Idea: It is arguable whether two-valued truth tables give correct meanings for certain sentential operators, and even whether they constitute legitimate explanations of any possible sentential operators. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.294) | |
| A reaction: See 'Many-valued logic' for examples of non-binary truth tables. Presumably logicians should aspire to make their semantics precise, as well as their syntax. |
| 11066 | Deduction is justified by the semantics of its metalanguage [Dummett, by Hanna] |
| Full Idea: For Dummett the semantics of the metalanguage is the external and objective source of the justification of deduction. | |
| From: report of Michael Dummett (The Justification of Deduction [1973]) by Robert Hanna - Rationality and Logic 3.4 | |
| A reaction: This is offered as an answer to the Lewis Carroll problem that justifying deduction seems to need deduction, thus leading to a regress. [There is a reply to Dummett by Susan Haack] |
| 19058 | Syntactic consequence is positive, for validity; semantic version is negative, with counterexamples [Dummett] |
| Full Idea: A plausible account is that the syntactic notion of consequence is for positive results, that some form of argument is valid; the semantic notion is required for negative results, that some argument is invalid, because a counterexample can be found. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.292) | |
| A reaction: This rings true for the two strategies of demonstration, the first by following the rules in steps, the second by using your imagination (or a tableau) to think up problems. |
| 19063 | Beth trees show semantics for intuitionistic logic, in terms of how truth has been established [Dummett] |
| Full Idea: Beth trees give a semantics for intuitionistic logic, by representing sentence meaning in terms of conditions under which it is recognised to have been established as true. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.305) |
| 19059 | In standard views you could replace 'true' and 'false' with mere 0 and 1 [Dummett] |
| Full Idea: Nothing is lost, on this view, if in the standard semantic treatment of classical sentential logic, we replace the standard truth-values 'true' and 'false' by the numbers 0 and 1. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.294) | |
| A reaction: [A long context will explain 'on this view'] He is discussing the relationship of syntactic and semantic consequence, and goes on to criticise simple binary truth-table accounts of connectives. Semantics on a computer would just be 0 and 1. |
| 19062 | Classical two-valued semantics implies that meaning is grasped through truth-conditions [Dummett] |
| Full Idea: The standard two-valued semantics for classical logic involves a conception under which to grasp the meaning of a sentence is to apprehend the conditions under which it is, or is not, true. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.305) | |
| A reaction: The idea is that you only have to grasp the truth tables for sentential logic, and that needs nothing more than knowing whether a sentence is true or false. I'm not sure where the 'conditions' creep in, though. |
| 19065 | Soundness and completeness proofs test the theory of meaning, rather than the logic theory [Dummett] |
| Full Idea: A proof of soundess or completeness is a test, not so much of the logical theory to which it applies, but of the theory of meaning which underlies the semantics. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.310) | |
| A reaction: These two types of proof concern how the syntax and the semantics match up, so this claim sounds plausible, though I tend to think of them as more like roadworthiness tests for logic, checking how well they function. |
| 7559 | Every part of the universe is body, and non-body is not part of it [Hobbes] |
| Full Idea: The world is corporeal, that is to say, body...and every part of the universe is body, and that which is not body is no part of the universe. | |
| From: Thomas Hobbes (Leviathan [1651], IV.46) | |
| A reaction: [Hobbes concedes existence to visible spirits, but not invisible ones]. This is the kind of remark which got Hobbes hated. It is also the sort of thing that makes him the best candidate for the 'first modern man'. |
| 2356 | Appearance and reality can be separated by mirrors and echoes [Hobbes] |
| Full Idea: If colours or sounds were in the bodies or objects that cause them, they could not be severed from them, as by glasses, and in echoes by reflection, we see they are; where we know the thing we see is in one place, the appearance in another. | |
| From: Thomas Hobbes (Leviathan [1651], 1.01) |
| 2357 | Dreams must be false because they seem absurd, but dreams don't see waking as absurd [Hobbes] |
| Full Idea: Because waking I often observe the absurdity of dreams, but never dream of the absurdity of my waking thoughts, I am well satisfied that, being awake, I know I dream not, though when I dream I think myself awake. | |
| From: Thomas Hobbes (Leviathan [1651], 1.02) |
| 19061 | An explanation is often a deduction, but that may well beg the question [Dummett] |
| Full Idea: An explanation is often a deductive argument, with the fact needing explaining as its conclusion. ...But the conclusion is usually given in advance, and we may only believe the premisses because they plausibly explain the conclusion. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.296) | |
| A reaction: [compressed (Dummett's wordy prose cries out for it!)] I suppose this works better in mathematics, which is central to Dummett's interests. In the real world the puzzle is not usually logically implied by its explanation. |
| 2358 | Freedom is absence of opposition to action; the idea of 'free will' is absurd [Hobbes] |
| Full Idea: If a man should talk to me of a 'free-will', or any 'free' but free from being hindered by opposition, I should not say that he were in an error, but that his words were without a meaning, that is to say, absurd. | |
| From: Thomas Hobbes (Leviathan [1651], 1.05) |
| 6214 | Liberty and necessity are consistent, as when water freely flows, by necessity [Hobbes] |
| Full Idea: Liberty and necessity are consistent: as in the water, that hath not only liberty, but a necessity of descending by the channel. | |
| From: Thomas Hobbes (Leviathan [1651], II.Ch.XI) | |
| A reaction: Hume asserts something similar (Idea 2223), but they both miss the point, which is that libertarians about water would have to believe it didn't need to follow gravity, but could refuse to flow. Freedom of will and freedom of action are quite different. |
| 23987 | The 'simple passions' are appetite, desire, love, aversion, hate, joy, and grief [Hobbes, by Goldie] |
| Full Idea: For Hobbes the 'simple passions' were appetite, desire, love, aversion, hate, joy, and grief. | |
| From: report of Thomas Hobbes (Leviathan [1651], I.6) by Peter Goldie - The Emotions 4 'Evidence' | |
| A reaction: This is the standard approach to emotions of Hobbes's time. Modern thinkers probably reject the idea that passions can be simple or basic. Rightly, I think. |
| 19064 | Holism is not a theory of meaning; it is the denial that a theory of meaning is possible [Dummett] |
| Full Idea: In the sense of giving a model for the content of a sentence, its representative power, holism is not a theory of meaning; it is the denial that a theory of meaning is possible. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.309) | |
| A reaction: This will obviously be because sentences just don't have meaning in isolation, so their meaning can't be given in terms of the sentences. |
| 2362 | The will is just the last appetite before action [Hobbes] |
| Full Idea: In deliberation, the last appetite or aversion immediately adhering to the action, or to the omission thereof, is that we call the Will. | |
| From: Thomas Hobbes (Leviathan [1651], 1.06) | |
| A reaction: I share his caution about 'the will', but his observation strikes me as inaccurate. When I drink, my 'will' is not my thirst. I take the will to be a feature of my reason. I gave my thirst permission to indulge itself. The will is practical reason? |
| 2363 | Reason is usually general, but deliberation is of particulars [Hobbes] |
| Full Idea: Reasoning is in general words, but deliberation for the most part is of particulars. | |
| From: Thomas Hobbes (Leviathan [1651], 1.06) |
| 2360 | 'Good' is just what we desire, and 'Evil' what we hate [Hobbes] |
| Full Idea: Whatsoever is the object of any man's appetite or desire, that is it which he for his part calleth 'Good'; and the object of his hate or aversion 'Evil'. | |
| From: Thomas Hobbes (Leviathan [1651], 1.06) | |
| A reaction: This meets the Frege-Geach Problem - that we can have these feelings while reading ancient history, but we can't possibly 'desire' any of that. This is better on evil than on good. |
| 2368 | Men's natural desires are no sin, and neither are their actions, until law makes it so [Hobbes] |
| Full Idea: The desires and other passions of man are in themselves no sin. No more are the actions that proceed from those passions, till they know a law that forbids them. | |
| From: Thomas Hobbes (Leviathan [1651], 1.13) | |
| A reaction: That is a pretty flat rejection of natural law, as you might expect from an empiricist. So prior to the first law-making, no one ever did anything wrong? Hm. |
| 2359 | Desire and love are the same, but in the desire the object is absent, and in love it is present [Hobbes] |
| Full Idea: Desire and love are the same thing, save that by desire we always signify the absence of the object, by love most commonly the presence of the same. | |
| From: Thomas Hobbes (Leviathan [1651], 1.06) | |
| A reaction: Implausible reductivism from Hobbes. Plenty of counterexamples to this. You work it out! |
| 2370 | All voluntary acts aim at some good for the doer [Hobbes] |
| Full Idea: Of the voluntary acts of every man, the object is some good to himself. | |
| From: Thomas Hobbes (Leviathan [1651], 1.14) | |
| A reaction: Nonsense. You can only describe sacrificial acts for loved ones, such as children, in this way if this proposal is a tautology. Hobbes cannot know the truth of this claim. |
| 8015 | Hobbes wants a contract to found morality, but shared values are needed to make a contract [MacIntyre on Hobbes] |
| Full Idea: Hobbes makes two incompatible demands of the original contract: he wishes it to be the foundation of all shared and common standards and rules; but he also wishes it to be a contract, which needs prior shared and common standards. | |
| From: comment on Thomas Hobbes (Leviathan [1651], Pt 1) by Alasdair MacIntyre - A Short History of Ethics Ch.10 | |
| A reaction: At the very least, the participants in a contract must be committed to keeping it even when it is not convenient. But a common purpose seems to be needed too, which makes the contract itself intrinsically valuable. Similar objections to Kant. |
| 2371 | A contract is a mutual transfer of rights [Hobbes] |
| Full Idea: The mutual transferring of right is that which men call 'contract'. | |
| From: Thomas Hobbes (Leviathan [1651], 1.14) |
| 2372 | The person who performs first in a contract is said to 'merit' the return, and is owed it [Hobbes] |
| Full Idea: He that performeth first in the case of a contract, is said to 'merit' that which he is to receive by the performance of the other, and he hath it as due. | |
| From: Thomas Hobbes (Leviathan [1651], 1.14) |
| 5337 | For Hobbes the Golden Rule concerns not doing things, whereas Jesus encourages active love [Hobbes, by Flanagan] |
| Full Idea: Hobbes put the Golden Rule as 'do NOT do to others what you would NOT want done to yourself'. Jesus's formulation encouraged active love. Most Westerners conceive their moral duty as not to do harm, rather than actively doing good. | |
| From: report of Thomas Hobbes (Leviathan [1651]) by Owen Flanagan - The Problem of the Soul p.20n | |
| A reaction: This idea probably runs very deep into western culture, where most people feel that they are being very morally good when they are sitting at home and not actually annoying anyone. Utilitarianism also offers a challenge to such complacency. |
| 2374 | In the violent state of nature, the merest suspicion is enough to justify breaking a contract [Hobbes] |
| Full Idea: If a covenant is made with neither party performing presently, but trust one another, in the condition of mere nature (which is war between men) upon reasonable suspicion, it is void. | |
| From: Thomas Hobbes (Leviathan [1651], 1.14) |
| 2375 | Suspicion will not destroy a contract, if there is a common power to enforce it [Hobbes] |
| Full Idea: If there be a common power set over both parties in a contract, with right and force sufficient to compel performance, a contract does not become void as soon as the parties are suspicious. | |
| From: Thomas Hobbes (Leviathan [1651], 1.14) |
| 8016 | Fear of sanctions is the only motive for acceptance of authority that Hobbes can think of [MacIntyre on Hobbes] |
| Full Idea: Hobbes has such a limited view of human motives that he cannot provide any other explanation for the acceptance of authority than the fear of sanctions.. | |
| From: comment on Thomas Hobbes (Leviathan [1651], Pt 1) by Alasdair MacIntyre - A Short History of Ethics Ch.10 | |
| A reaction: There are two alternative views - the conservative view that people naturally welcome and even need authority, because they need to be led; or the Aristotelian view that people are naturally communal, and authority is part of community life. |
| 2377 | No one who admitted to not keeping contracts could ever be accepted as a citizen [Hobbes] |
| Full Idea: He therefore that breaketh his covenant, and consequently declareth that he thinks he may with reason do so, cannot be received into any society. | |
| From: Thomas Hobbes (Leviathan [1651], 1.15) |
| 2379 | If there is a good reason for breaking a contract, the same reason should have stopped the making of it [Hobbes] |
| Full Idea: If any fault of man be sufficient to discharge our covenant made, the same ought in reason to have been sufficient to have hindered the making of it. | |
| From: Thomas Hobbes (Leviathan [1651], 1.15) |
| 2373 | The first performer in a contract is handing himself over to an enemy [Hobbes] |
| Full Idea: He which performeth first in a contract, does but betray himself to his enemy. | |
| From: Thomas Hobbes (Leviathan [1651], 1.14) |
| 2382 | Someone who keeps all his contracts when others are breaking them is making himself a prey to others [Hobbes] |
| Full Idea: He that should be modest and tractable, and perform all the promises, in such time and place where no man else should do so, should but make himself a prey to others. | |
| From: Thomas Hobbes (Leviathan [1651], 1.15) |
| 2383 | Virtues are a means to peaceful, sociable and comfortable living [Hobbes] |
| Full Idea: The writers of moral philosophy, though they acknowledge the same virtues and vices, yet not seeing wherein consisted their goodness, nor that they come to be praised as the means of peaceable, sociable and comfortable living. | |
| From: Thomas Hobbes (Leviathan [1651], 1.15) |
| 2376 | Injustice is the failure to keep a contract, and justice is the constant will to give what is owed [Hobbes] |
| Full Idea: The definition of 'injustice' is no other than the not performance of covenant….. and 'justice' is the constant will of giving to every man his own. | |
| From: Thomas Hobbes (Leviathan [1651], 1.15) |
| 2367 | In time of war the life of man is solitary, poor, nasty, brutish and short [Hobbes] |
| Full Idea: In a time of war…. there is continual fear, and danger of violent death, and the life of man is solitary, poor, nasty, brutish and short. | |
| From: Thomas Hobbes (Leviathan [1651], 1.13) |
| 19764 | Hobbes attributed to savages the passions which arise in a law-bound society [Hobbes, by Rousseau] |
| Full Idea: Hobbes had wrongly injected into the savage man's concern for self-preservation the need to satisfy a multitude of passions which are the product of society and which have made laws necessary. | |
| From: report of Thomas Hobbes (Leviathan [1651]) by Jean-Jacques Rousseau - Discourse on the Origin of Inequality Part I | |
| A reaction: Hobbes's famous remark concerns a state of war, which is quite a sophisticated state of conflict between well formed social groups. Rousseau's savage is fairly solitary, so won't be involved in war. |
| 20566 | Hobbes says the people voluntarily give up their sovereignty, in a contract with a ruler [Hobbes, by Oksala] |
| Full Idea: While Hobbes had held that the people were the final source of political authority, he had argued that in entering the social contract they gave up their sovereignty by transferring all power to an absolute ruler. | |
| From: report of Thomas Hobbes (Leviathan [1651]) by Johanna Oksala - Political Philosophy: all that matters Ch.5 | |
| A reaction: Later the idea of 'inalienable' rights crept in. If you volunteer for exploitation or slavery, that still doesn't justify them. Sadism is presumably not justified by masochism. |
| 2366 | There is not enough difference between people for one to claim more benefit than another [Hobbes] |
| Full Idea: The difference between man and man is not so considerable as that one man can thereupon claim to himself any benefit to which another may not pretend as well as he. | |
| From: Thomas Hobbes (Leviathan [1651], 1.13) |
| 20485 | Hobbes says people are roughly equal; Locke says there is no right to impose inequality [Hobbes, by Wolff,J] |
| Full Idea: Hobbes's principle of equality was a claim about the mental and physical capabilities of all people. For Locke it is a moral claim about rights: no person has a natural right to subordinate any other. | |
| From: report of Thomas Hobbes (Leviathan [1651]) by Jonathan Wolff - An Introduction to Political Philosophy (Rev) 1 'Locke' | |
| A reaction: There are obvious questions to ask about the claim that people are naturally equal. For the second one, does the lion have a natural right to subordinate the gazelle? Who cares! I'm inclined to be consequentialist about equality. |
| 2369 | If we seek peace and defend ourselves, we must compromise on our rights [Hobbes] |
| Full Idea: From the first law of nature (that we seek peace, but also defend ourselves) comes the second: that a man be willing to lay down his rights to all things, and be contented with so much liberty against other men as he would allow other men against himself. | |
| From: Thomas Hobbes (Leviathan [1651], 1.14) |
| 20484 | We should obey the laws of nature, provided other people are also obeying them [Hobbes, by Wolff,J] |
| Full Idea: Hobbes's position is that we have a duty to obey the Laws of Nature when others around us are known (or can reasonably be expected) to be obeying them too, and so our compliance will not be exploited. | |
| From: report of Thomas Hobbes (Leviathan [1651]) by Jonathan Wolff - An Introduction to Political Philosophy (Rev) 1 'Hobbes' | |
| A reaction: In particular, we should keep contracts. Hobbes doesn't seem fully committed to keeping facts and values separate. |
| 7573 | The legal positivism of Hobbes said law is just formal or procedural [Hobbes, by Jolley] |
| Full Idea: Hobbes was one of the first to propose the view known as 'legal positivism' - that the criterion for deciding whether a rule is a genuine law is entirely formal or procedural | |
| From: report of Thomas Hobbes (Leviathan [1651]) by Nicholas Jolley - Leibniz Ch.7 | |
| A reaction: This was opposed to the tradition of natural law, deriving from Aquinas. It is part of a picture of values draining out of the world as science comes to dominate. The is/ought distinction is its culmination. Power replaces virtue, and Thrasymachus wins. |
| 2380 | Punishment should only be for reform or deterrence [Hobbes] |
| Full Idea: We are forbidden to inflict punishment with any other design than for correction of the offender, or direction of others. | |
| From: Thomas Hobbes (Leviathan [1651], 1.15) |
| 2361 | If fear of unknown powers is legal it is religion, if it is illegal it is superstition [Hobbes] |
| Full Idea: Fear of power invisible, feigned by the mind or imagined from tales publicly allowed, is religion; not allowed, is superstition. | |
| From: Thomas Hobbes (Leviathan [1651], 1.06) |
| 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 |
| 2364 | Causation is only observation of similar events following each other, with nothing visible in between [Hobbes] |
| Full Idea: In knowing the meaning of 'causing', men can only observe and remember what they have seen to precede the like effect at some other time, without seeing between the antecedent and subsequent event any dependence or connexion at all. | |
| From: Thomas Hobbes (Leviathan [1651], 1.12) |
| 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. |
| 2365 | Religion is built on ignorance and misinterpretation of what is unknown or frightening [Hobbes] |
| Full Idea: In these four things - opinion of ghosts, ignorance of second causes, devotion towards what men fear, and taking of things casual for prognostics, consisteth the natural seed of religion. | |
| From: Thomas Hobbes (Leviathan [1651], 1.12) |
| 2378 | Belief in an afterlife is based on poorly founded gossip [Hobbes] |
| Full Idea: Knowledge of man's estate after death, and its rewards, is a belief grounded upon other men's sayings that they knew it supernaturally, or they knew those, that knew those, that knew others, that knew it supernaturally. | |
| From: Thomas Hobbes (Leviathan [1651], 1.15) |