29 ideas
| 10688 | 'Equivocation' is when terms do not mean the same thing in premises and conclusion [Beall/Restall] |
| Full Idea: 'Equivocation' is when the terms do not mean the same thing in the premises and in the conclusion. | |
| From: JC Beall / G Restall (Logical Consequence [2005], Intro) |
| 10690 | Formal logic is invariant under permutations, or devoid of content, or gives the norms for thought [Beall/Restall] |
| Full Idea: Logic is purely formal either when it is invariant under permutation of object (Tarski), or when it has totally abstracted away from all contents, or it is the constitutive norms for thought. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 2) | |
| A reaction: [compressed] The third account sounds rather woolly, and the second one sounds like a tricky operation, but the first one sounds clear and decisive, so I vote for Tarski. |
| 10691 | Logical consequence needs either proofs, or absence of counterexamples [Beall/Restall] |
| Full Idea: Technical work on logical consequence has either focused on proofs, where validity is the existence of a proof of the conclusions from the premises, or on models, which focus on the absence of counterexamples. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 3) |
| 10695 | Logical consequence is either necessary truth preservation, or preservation based on interpretation [Beall/Restall] |
| Full Idea: Two different views of logical consequence are necessary truth-preservation (based on modelling possible worlds; favoured by Realists), or truth-preservation based on the meanings of the logical vocabulary (differing in various models; for Anti-Realists). | |
| From: JC Beall / G Restall (Logical Consequence [2005], 2) | |
| A reaction: Thus Dummett prefers the second view, because the law of excluded middle is optional. My instincts are with the first one. |
| 10689 | A step is a 'material consequence' if we need contents as well as form [Beall/Restall] |
| Full Idea: A logical step is a 'material consequence' and not a formal one, if we need the contents as well as the structure or form. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 2) |
| 10696 | A 'logical truth' (or 'tautology', or 'theorem') follows from empty premises [Beall/Restall] |
| Full Idea: If a conclusion follows from an empty collection of premises, it is true by logic alone, and is a 'logical truth' (sometimes a 'tautology'), or, in the proof-centred approach, 'theorems'. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 4) | |
| A reaction: These truths are written as following from the empty set Φ. They are just implications derived from the axioms and the rules. |
| 10693 | Models are mathematical structures which interpret the non-logical primitives [Beall/Restall] |
| Full Idea: Models are abstract mathematical structures that provide possible interpretations for each of the non-logical primitives in a formal language. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 3) |
| 10692 | Hilbert proofs have simple rules and complex axioms, and natural deduction is the opposite [Beall/Restall] |
| Full Idea: There are many proof-systems, the main being Hilbert proofs (with simple rules and complex axioms), or natural deduction systems (with few axioms and many rules, and the rules constitute the meaning of the connectives). | |
| From: JC Beall / G Restall (Logical Consequence [2005], 3) |
| 1350 | Continuity is needed for existence, otherwise we would say a thing existed after it ceased to exist [Reid] |
| Full Idea: Identity supposes an uninterrupted continuance of existence….Otherwise we must suppose a being to exist after it has ceased to exist, and to have existed before it was produced, which are manifest contradictions. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 4) | |
| A reaction: I take the point to be that if something is supposed to survive a gap in its existence, that must imply that it somehow exists during the gap. If a light flashes on and off, is it really a new entity each time? |
| 21322 | We treat slowly changing things as identical for the sake of economy in language [Reid] |
| Full Idea: All bodies, as they consist of innumerable parts, are subject to continual changes of their substance. When such changes are gradual, because language could not afford a different name for each state, it retains the same name and is considered the same. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 4) | |
| A reaction: This is hard to deny. We could hardly rename a child each morning. Simlarly, we can't have a unique name for each leaf on a tree. Economy of language explains a huge amount in philosophy. |
| 21320 | Identity is familiar to common sense, but very hard to define [Reid] |
| Full Idea: Every man of common sense has a clear and distinct notion of identity. If you ask for a definition of identity, I confess I can give none. It is too simple a notion. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 4) | |
| A reaction: 'Identical' seems to be a two-place predicate, but the only strict way two things can be identical is if there is actually just one thing. In which case just drop the word 'identity' (instead of defining it), and say there is just one thing here. |
| 1367 | Identity can only be affirmed of things which have a continued existence [Reid] |
| Full Idea: Identity can only be affirmed of things which have a continued existence. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 6) | |
| A reaction: This doesn't mean that Reid thinks there is nothing more to the identity than their similitude. But he, like Hume, denies that there is personal identity at any given instant. Reid is better at criticism than at formulating his own theory. |
| 23644 | Without memory we could have no concept of duration [Reid] |
| Full Idea: It is impossible to show how we could acquire a notion of duration if we had no memory. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], 1) | |
| A reaction: We would probably not have a notion of duration if we possessed a memory, but nothing ever changed. Maybe in Shoemaker's frozen worlds they retain memories, but nothing happens? |
| 23643 | We all trust our distinct memories (but not our distinct imaginings) [Reid] |
| Full Idea: Every man feels he must believe what he distinctly remembers, though he can give no other reason for his belief, but that he remembers the thing distinctly; whereas, when he merely distinctly imagines a thing, he has no belief in it upon that account. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], 1) | |
| A reaction: The word 'distinct' is doing some heavy work here. I fear that believing the memory is the only criterion we have for calling it distinct. As a boy I was persuaded to change my testimony about a car accident, and I realised I was not distinct about it. |
| 1356 | A person is a unity, and doesn't come in degrees [Reid] |
| Full Idea: The identity of a person is a perfect identity: wherever it is real, it admits of no degrees; and it is impossible that a person should be in part the same, and in part different; because a person is a 'monad', and is not divisible into parts. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 4) | |
| A reaction: I don't accept this, because I don't accept the metaphysics needed to underpin it. To watch a person with Alzheimer's disease fade out of existence before they die seems sufficient counter-evidence. I believe in personal identity, but it isn't 'perfect'. |
| 1359 | Personal identity is the basis of all rights, obligations and responsibility [Reid] |
| Full Idea: Identity, when applied to persons, has no ambiguity, and admits of no degrees. It is the foundation of all rights and obligations, and of all accountableness. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 4) | |
| A reaction: This seems to me to be one of the key mistakes in all of philosophy - thinking that items must always be all-or-nothing. If a person deteriorates through Alzheimer's, there seem to be obvious degrees of personhood. Responsibility comes in degrees, too. |
| 21319 | I can hardly care about rational consequence if it wasn't me conceiving the antecedent [Reid] |
| Full Idea: The conviction of personal identity is indispensably necessary to all exercise of reason. Reasoning is made up of successive parts. Without the conviction that the antecedent have been seen by me, I could have no reason to proceed to the consequent. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 4) | |
| A reaction: Society needs philosophers precisely to point such things out. It isn't conclusive, but populist waffle about the self not existing undermines the very concept of a 'train of thought', which everybody is signed up to. Trains of thought can take years. |
| 21323 | The identity of a thief is only known by similarity, but memory gives certainty in our own case [Reid] |
| Full Idea: A man challenges a thief in possession of his horse only on similarity. The testimony of witnesses to the identity of a person is commonly grounded on no other evidence. ...Evidence of our own identity is grounded in memory, and gives undoubted certainty. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 4) | |
| A reaction: With other people the best we can hope for is type-identity, hoping that each individual being is a unique type, but with otherselves we are always confident of establishing token identity. Could I have been someone different yesterday, without realising? |
| 21321 | Memory reveals my past identity - but so does testimony of other witnesses [Reid] |
| Full Idea: Although memory gives the most irresistible evidence of my being the identical person that did such a thing, I may have other good evidence of things which befell me. I know who bare me and suckled me, but I do not remember those events. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 4) | |
| A reaction: A splendidly accurate and simple observation. Reid's criticisms of Locke are greatly superior to those of Butler. We now have vast collections of photographs showing our past identities. |
| 21324 | If consciousness is transferable 20 persons can be 1; forgetting implies 1 can be 20 [Reid] |
| Full Idea: If the same consciousness can be transferred from one intelligent being to another, then two or twenty beings may be the same person. If he may lose the consciousness of actions done by him, one intelligent being may be two or twenty different persons. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 6) | |
| A reaction: Reid says Locke was aware of these two implications of his theory of personal identity (based on consciousness). The first example is me replicated like software. The second is if I forget that I turned the light off, then who did turn the light off? |
| 21325 | Boy same as young man, young man same as old man, old man not boy, if forgotten! [Reid] |
| Full Idea: Suppose a brave officer, flogged as a boy for robbing an orchard, to have captured a standard in his first campaign, and become a general in advanced life. [If the general forgets the flogging] he is and at the same time is not the same as the boy. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 6) | |
| A reaction: The point is that strict identity has to be transitive, and if the general forgets his boyhood that breaks the transitivity. If identity is less strict there is no problem. The general may only have memories related to some part of his boyhood. |
| 21327 | If a stolen horse is identified by similitude, its identity is not therefore merely similitude [Reid] |
| Full Idea: When a stolen horse is claimed, the only evidence that this is the same horse is similitude. But would it not be ridiculous from this to infer that the identity of a horse consists in similitude only? | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 6) | |
| A reaction: Actually that is exactly Hume's view of the matter (Idea 21292). For a strict empiricist there is nothing else be close resemblance over time. I prefer Reid's account to Hume's. - but then I am not a 'strict' empiricist. |
| 1366 | If consciousness is personal identity, it is continually changing [Reid] |
| Full Idea: Is it not strange that the identity of a person should consist in a thing (consciousness) which is continually changing? | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 6) | |
| A reaction: This is the panicky slippery slope view of Locke, that sees his doctrine as the first step to the destruction of religion. The fact is, though, that parts of my consciousness changes continually, but other parts stay the same for years on end. |
| 1352 | Thoughts change continually, but the self doesn't [Reid] |
| Full Idea: My thoughts, and actions, and feelings, change every moment: they have no continued, but a successive, existence: but that self, or I, to which they belong, is permanent. | |
| From: Thomas Reid (Essays on Intellectual Powers 3: Memory [1785], III.Ch 4) | |
| A reaction: The word 'permanent' may be excessive, but one could hardly say there is nothing more to personal identity than the contents of consciousnes, given how much and how quickly those continually fluctuate. |
| 18225 | If we can't reason about value, we can reason about the unconditional source of value [Korsgaard] |
| Full Idea: If you can only know what is intrinsically valuable through intuition (as Moore claims), you can still argue about what is unconditionally valuable. There must be something unconditionally valuable because there must be a source of value. | |
| From: Christine M. Korsgaard (Aristotle and Kant on the Source of Value [1986], 8 'Three') | |
| A reaction: If you only grasped the values through intuition, does that give you enough information to infer the dependence relations between values? |
| 18228 | An end can't be an ultimate value just because it is useless! [Korsgaard] |
| Full Idea: If what is final is whatever is an end but never a means, ...why should something be more valuable just because it is useless? | |
| From: Christine M. Korsgaard (Aristotle and Kant on the Source of Value [1986], 8 'Finality') | |
| A reaction: Korsgaard is offering this as a bad reading of what Aristotle intends. |
| 18224 | Goodness is given either by a psychological state, or the attribution of a property [Korsgaard] |
| Full Idea: 'Subjectivism' identifies good ends with or by reference to some psychological state. ...'Objectivism' says that something is good as an end if a property, intrinsic goodness, is attributed to it. | |
| From: Christine M. Korsgaard (Aristotle and Kant on the Source of Value [1986], 8 'Three') |
| 18233 | Contemplation is final because it is an activity which is not a process [Korsgaard] |
| Full Idea: It is because contemplation is an activity that is not also a process that Aristotle identifies it as the most final good. | |
| From: Christine M. Korsgaard (Aristotle and Kant on the Source of Value [1986], 8 'Activity') | |
| A reaction: Quite a helpful way of labelling what Aristotle has in mind. So should we not aspire to be involved in processes, except reluctantly? I take the mind itself to be a process, so that may be difficult! |
| 18226 | For Aristotle, contemplation consists purely of understanding [Korsgaard] |
| Full Idea: Contemplation, as Aristotle understand it, is not research or inquiry, but an activity that ensues on these: an activity that consists in understanding. | |
| From: Christine M. Korsgaard (Aristotle and Kant on the Source of Value [1986], 8 'Aristotle') | |
| A reaction: Fairly obvious, when you read the last part of 'Ethics', but helpful in grasping Aristotle, because understanding is the objective of 'Posterior Analytics' and 'Metaphysics', so he tells you how to achieve the ideal moral state. |