24 ideas
| 19115 | You can 'rebut' an argument's conclusion, or 'undercut' its premises [Antonelli] |
| Full Idea: A 'rebut' of an argument establishes that its conclusion is not the case. An 'undercut' of the argument shows that the premises do not support that conclusion. | |
| From: G. Aldo Antonelli (Non-Monotonic Logic [2014], 3.2) |
| 19119 | We infer that other objects are like some exceptional object, if they share some of its properties [Antonelli] |
| Full Idea: The exceptional status of an object with respect to some default is more likely to spread to other objects if they share properties with that object that may play a role in explaining the exceptional status. | |
| From: G. Aldo Antonelli (Non-Monotonic Logic [2014], 4) | |
| A reaction: This is an example of the sort of rational behaviour we exhibit, and which a 'real life' logic would somehow need to capture. I would suggest the essentialist logic designed by Kit Fine as a first port of call. |
| 19111 | Reasoning may be defeated by new premises, or by finding out more about the given ones [Antonelli] |
| Full Idea: Most defeasible reasoning is externally dynamic, affected by the addition of further premises. But there is also an internal (or 'diachronic') dynamic, when further analysis reveals more about the given premises. | |
| From: G. Aldo Antonelli (Non-Monotonic Logic [2014], 1) |
| 19114 | Should we accept Floating Conclusions, derived from two arguments in conflict? [Antonelli] |
| Full Idea: There is much discussion of whether Floating Conclusions should be derived, given that they were derived from two arguments which conflict with one another. | |
| From: G. Aldo Antonelli (Non-Monotonic Logic [2014], 2.3) |
| 19113 | Weakest Link Principle: prefer the argument whose weakest link is the stronger [Antonelli] |
| Full Idea: In the Weakest Link Principle, an argument is preferred to another conflicting argument if its weakest defeasible link is stronger than the weakest defeasible link in the conflicting argument. | |
| From: G. Aldo Antonelli (Non-Monotonic Logic [2014], 2.1) | |
| A reaction: [He cites John Pollock 1991] This sounds like the elementary principle applied when choosing a rope by which to hang a large weight above your head. It gets non-monotonic logic off the ground - if you know how to evaluate 'weakest'. |
| 19116 | Non-monotonic core: Reflexivity, Cut, Cautious Monotonicity, Left Logical Equivalence, Right Weakening [Antonelli] |
| Full Idea: Conservative core of non-monotonic logic:Reflexivity (p proves p), Cut (if p proves q, it proves their joint implications), Cautious Monotonicity, Left Logical Equivalence (equivalences have same consequences), Right Weakening (non-m preserves classical). | |
| From: G. Aldo Antonelli (Non-Monotonic Logic [2014], 3.5.1) | |
| A reaction: [Highly compressed, and without symbols] |
| 19117 | We can rank a formula by the level of surprise if it were to hold [Antonelli] |
| Full Idea: We can think of an 'ordinal ranking function' κ([φ)] as the level of surprise we would face were φ to hold, up to maximal surprise. | |
| From: G. Aldo Antonelli (Non-Monotonic Logic [2014], 3.5.2) | |
| A reaction: This suggests that Bayes's Theorem might be relevant to non-monotonic logic. This suggests that registering surprise would need to be an important feature of robot behaviour. |
| 19118 | People don't actually use classical logic, but may actually use non-monotonic logic [Antonelli] |
| Full Idea: Test subjects seem to perform very poorly in various reasoning tests (Wason Selection, Suppression Task), suggesting logic has a subordinate role, but this may be using classical logic, where non-monotonic logics would be more appropriate. | |
| From: G. Aldo Antonelli (Non-Monotonic Logic [2014], 4) | |
| A reaction: Fred Sommers presents his Term Logic (based on Aristotle) as closer to how people actually reason. It is certainly crazy to infer that most people's everyday reasoning is irrational. Induction is highly rational; it's just not deductive. |
| 19110 | In classical logic the relation |= has Monotony built into its definition [Antonelli] |
| Full Idea: In classical logic, Monotony follows immediately from the nature of the relation |=, for Γ |= φ holds precisely when φ is true on every interpretation on which all sentences in Γ are true. | |
| From: G. Aldo Antonelli (Non-Monotonic Logic [2014], 1) | |
| A reaction: That is, semantic consequence (|=) is defined in terms of a sentence (φ) always being true if some other bunch of sentences (Γ) are true. Hence the addition of further sentences to Γ will make no difference - which is Monotony. |
| 19112 | Cautious Monotony ignores proved additions; Rational Monotony fails if the addition's negation is proved [Antonelli] |
| Full Idea: Basic Monotony: something stays proved if further premises are added. Cautious Monotony: the addition of something which has been proved makes no difference. Rational Monotony: it stays proved as long as the addition's negation hasn't been proved. | |
| From: G. Aldo Antonelli (Non-Monotonic Logic [2014], 1) | |
| A reaction: [A compressed and non-symbolic summary] |
| 5987 | Alcmaeon was the first to say the brain is central to thinking [Alcmaeon, by Staden, von] |
| Full Idea: Alcmaeon apparently was the first Greek to assign central cognitive and biological functions to the brain. | |
| From: report of Alcmaeon (fragments/reports [c.490 BCE]) by Heinrich von Staden - Alcmaeon | |
| A reaction: The name of Alcmaeon should be remembered with honour. This was 200 years before Aristotle, who still hadn't worked it out. I presume Alcmaeon inferred the truth from head injuries, which is overwhelming evidence, if you notice it. |
| 5901 | Is 'productive of happiness' the definition of 'right', or the cause of it? [Ross on Bentham] |
| Full Idea: Bentham has not made up his mind whether he thinks that 'right' means 'productive of the general happiness', or that being productive of the general happiness is what makes acts right (and he would have thought the difference unimportant). | |
| From: comment on Jeremy Bentham (Intro to Principles of Morals and Legislation [1789]) by W. David Ross - The Right and the Good §I | |
| A reaction: The issue is whether rightness exists as a concept separate from happiness. I take it Bentham would vote for the first reading, as he has no interest in what is right, apart from increasing happiness. |
| 5271 | Prejudice apart, push-pin has equal value with music and poetry [Bentham] |
| Full Idea: Prejudice apart, the game of push-pin is of equal value with the arts and science of music and poetry. | |
| From: Jeremy Bentham (Constitutional Code I [1827], p.139), quoted by J.R. Dinwiddy - Bentham p.114 | |
| A reaction: Mill quoted this with implied outrage, but Bentham was attacking public subsidies to the arts when he said it. It is a basic idea in the debate on pleasure - that pleasures are only distinguished by their intensity, not some other value. |
| 5934 | Of Bentham's 'dimensions' of pleasure, only intensity and duration matter [Ross on Bentham] |
| Full Idea: Most of Bentham's 'dimensions' of pleasure refer to further pleasures, or are irrelevant to the pleasure; we are left with intensity and duration as the characteristics on which depend the value of a pleasure qua pleasure, and there is nothing to add. | |
| From: comment on Jeremy Bentham (Intro to Principles of Morals and Legislation [1789]) by W. David Ross - The Right and the Good §VI | |
| A reaction: I agree. When Bentham produces his list he seems to be trying to add a bogus enrichment to what is really a rather crude and basic notion of the aim of life. Your simple hedonist appears to only desire high intensity and long duration. |
| 3777 | Pleasure and pain control all human desires and duties [Bentham] |
| Full Idea: Nature has placed mankind under the governance of two sovereign masters, pain and pleasure. It is for them alone to point out what we ought to do, as well as to determine what we shall do. | |
| From: Jeremy Bentham (Intro to Principles of Morals and Legislation [1789], I.1) | |
| A reaction: Ridiculous. Both halves are false. We pursue things for other reasons, and to deny this makes his idea a tautology. Deep ecology has nothing to do with human pleasure or pain. |
| 3554 | Bentham thinks happiness is feeling good, but why use morality to achieve that? [Annas on Bentham] |
| Full Idea: It is easy to fall into Bentham's mindless assumption that happiness must be a specific state of feeling good about something, but it is mysterious why anyone would think morality a good strategy for achieving this. | |
| From: comment on Jeremy Bentham (Intro to Principles of Morals and Legislation [1789]) by Julia Annas - The Morality of Happiness 2.7 |
| 3781 | The value of pleasures and pains is their force [Bentham] |
| Full Idea: It behoves the legislator to understand the force of pleasures and pains, which is their value. | |
| From: Jeremy Bentham (Intro to Principles of Morals and Legislation [1789], IV.1) |
| 20977 | Natural rights are nonsense, and unspecified natural rights is nonsense on stilts [Bentham] |
| Full Idea: Natural rights is simple nonsense: natural and imprescriptible rights, rhetorical nonsense — nonsense upon stilts. | |
| From: Jeremy Bentham (Anarchical Fallacies: on the Declaration of Rights [1796]) | |
| A reaction: If you want your opinion to be remembered, express it memorably! I take natural rights to be the basic principles and values which are obvious to almost everyone when they come for formulate legal rights (which are the only true rights). |
| 3778 | The community's interest is a sum of individual interests [Bentham] |
| Full Idea: The interest of the community is the sum of the interests of the several members who compose it. | |
| From: Jeremy Bentham (Intro to Principles of Morals and Legislation [1789], I.4) |
| 21003 | Only laws can produce real rights; rights from 'law of nature' are imaginary [Bentham] |
| Full Idea: Right, the substantive right, is the child of law; from real laws come real rights; but from imaginary laws, from 'law of nature' can come only imaginary rights. | |
| From: Jeremy Bentham (Anarchical Fallacies: on the Declaration of Rights [1796], II.523), quoted by Amartya Sen - The Idea of Justice 17 'Ethics' | |
| A reaction: I am coming to agree with this. What are called 'natural rights' are just self-evident good reasons why someone should be allowed a right. A right can, of course, come from an informal agreement. The question is: why award that particular legal right? |
| 20280 | Large mature animals are more rational than babies. But all that really matters is - can they suffer? [Bentham] |
| Full Idea: A full-grown horse or dog is beyond comparison a more rational animal than an infant of a day, or even a month, old. But suppose they be otherwise, what would it avail? The question is not, Can they reason? nor Can they talk? but, Can they suffer? | |
| From: Jeremy Bentham (Intro to Principles of Morals and Legislation [1789], XVIII 1 n), quoted by Peter Singer - Practical Ethics 03 | |
| A reaction: This is certainly an inspiring, and even shocking question, which never seems to have been so directly asked before in the entire history of European thought. Awesome. |
| 3779 | Unnatural, when it means anything, means infrequent [Bentham] |
| Full Idea: Unnatural, when it means anything, means unfrequent. | |
| From: Jeremy Bentham (Intro to Principles of Morals and Legislation [1789], II.14 n8.9) |
| 3780 | We must judge a thing morally to know if it conforms to God's will [Bentham] |
| Full Idea: It is necessary to know first whether a thing is right in order to know from thence whether it be conformable to the will of God. | |
| From: Jeremy Bentham (Intro to Principles of Morals and Legislation [1789], II.18) |
| 24043 | Soul must be immortal, since it continually moves, like the heavens [Alcmaeon, by Aristotle] |
| Full Idea: Alcmaeon says that the soul is immortal because it resembles immortal things and that this affection belongs to it because it is always in movement, like divine things, such the moon, the sun, the stars and the whole heaven. | |
| From: report of Alcmaeon (fragments/reports [c.490 BCE], DK 24) by Aristotle - De Anima 405a30 | |
| A reaction: Hm. Fish and rivers seem to be continually moving too. Presumably we are like gods, but then Greek gods seem awfully like humans. I don't know the history of belief in immortality; an interesting topic. |