23 ideas
| 18781 | Inconsistency doesn't prevent us reasoning about some system [Mares] |
| Full Idea: We are able to reason about inconsistent beliefs, stories, and theories in useful and important ways | |
| From: Edwin D. Mares (Negation [2014], 1) |
| 18790 | Intuitionism as natural deduction has no rule for negation [Mares] |
| Full Idea: In intuitionist logic each connective has one introduction and one elimination rule attached to it, but in the classical system we have to add an extra rule for negation. | |
| From: Edwin D. Mares (Negation [2014], 5.5) | |
| A reaction: How very intriguing. Mares says there are other ways to achieve classical logic, but they all seem rather cumbersome. |
| 18789 | Intuitionist logic looks best as natural deduction [Mares] |
| Full Idea: Intuitionist logic appears most attractive in the form of a natural deduction system. | |
| From: Edwin D. Mares (Negation [2014], 5.5) |
| 18787 | Three-valued logic is useful for a theory of presupposition [Mares] |
| Full Idea: One reason for wanting a three-valued logic is to act as a basis of a theory of presupposition. | |
| From: Edwin D. Mares (Negation [2014], 3.1) | |
| A reaction: [He cites Strawson 1950] The point is that you can get a result when the presupposition does not apply, as in talk of the 'present King of France'. |
| 18793 | Material implication (and classical logic) considers nothing but truth values for implications [Mares] |
| Full Idea: The problem with material implication, and classical logic more generally, is that it considers only the truth value of formulas in deciding whether to make an implication stand between them. It ignores everything else. | |
| From: Edwin D. Mares (Negation [2014], 7.1) | |
| A reaction: The obvious problem case is conditionals, and relevance is an obvious extra principle that comes to mind. |
| 18784 | In classical logic the connectives can be related elegantly, as in De Morgan's laws [Mares] |
| Full Idea: Among the virtues of classical logic is the fact that the connectives are related to one another in elegant ways that often involved negation. For example, De Morgan's Laws, which involve negation, disjunction and conjunction. | |
| From: Edwin D. Mares (Negation [2014], 2.2) | |
| A reaction: Mares says these enable us to take disjunction or conjunction as primitive, and then define one in terms of the other, using negation as the tool. |
| 18786 | Excluded middle standardly implies bivalence; attacks use non-contradiction, De M 3, or double negation [Mares] |
| Full Idea: On its standard reading, excluded middle tells us that bivalence holds. To reject excluded middle, we must reject either non-contradiction, or ¬(A∧B) ↔ (¬A∨¬B) [De Morgan 3], or the principle of double negation. All have been tried. | |
| From: Edwin D. Mares (Negation [2014], 2.2) |
| 18780 | Standard disjunction and negation force us to accept the principle of bivalence [Mares] |
| Full Idea: If we treat disjunction in the standard way and take the negation of a statement A to mean that A is false, accepting excluded middle forces us also to accept the principle of bivalence, which is the dictum that every statement is either true or false. | |
| From: Edwin D. Mares (Negation [2014], 1) | |
| A reaction: Mates's point is to show that passively taking the normal account of negation for granted has important implications. |
| 18782 | The connectives are studied either through model theory or through proof theory [Mares] |
| Full Idea: In studying the logical connectives, philosophers of logic typically adopt the perspective of either model theory (givng truth conditions of various parts of the language), or of proof theory (where use in a proof system gives the connective's meaning). | |
| From: Edwin D. Mares (Negation [2014], 1) | |
| A reaction: [compressed] The commonest proof theory is natural deduction, giving rules for introduction and elimination. Mates suggests moving between the two views is illuminating. |
| 18783 | Many-valued logics lack a natural deduction system [Mares] |
| Full Idea: Many-valued logics do not have reasonable natural deduction systems. | |
| From: Edwin D. Mares (Negation [2014], 1) |
| 18792 | Situation semantics for logics: not possible worlds, but information in situations [Mares] |
| Full Idea: Situation semantics for logics consider not what is true in worlds, but what information is contained in situations. | |
| From: Edwin D. Mares (Negation [2014], 6.2) | |
| A reaction: Since many theoretical physicists seem to think that 'information' might be the most basic concept of a natural ontology, this proposal is obviously rather appealing. Barwise and Perry are the authors of the theory. |
| 18785 | Consistency is semantic, but non-contradiction is syntactic [Mares] |
| Full Idea: The difference between the principle of consistency and the principle of non-contradiction is that the former must be stated in a semantic metalanguage, whereas the latter is a thesis of logical systems. | |
| From: Edwin D. Mares (Negation [2014], 2.2) |
| 18788 | For intuitionists there are not numbers and sets, but processes of counting and collecting [Mares] |
| Full Idea: For the intuitionist, talk of mathematical objects is rather misleading. For them, there really isn't anything that we should call the natural numbers, but instead there is counting. What intuitionists study are processes, such as counting and collecting. | |
| From: Edwin D. Mares (Negation [2014], 5.1) | |
| A reaction: That is the first time I have seen mathematical intuitionism described in a way that made it seem attractive. One might compare it to a metaphysics based on processes. Apparently intuitionists struggle with infinite sets and real numbers. |
| 18791 | In 'situation semantics' our main concepts are abstracted from situations [Mares] |
| Full Idea: In 'situation semantics' individuals, properties, facts, and events are treated as abstractions from situations. | |
| From: Edwin D. Mares (Negation [2014], 6.1) | |
| A reaction: [Barwise and Perry 1983 are cited] Since I take the process of abstraction to be basic to thought, I am delighted to learn that someone has developed a formal theory based on it. I am immediately sympathetic to situation semantics. |
| 5078 | Kant and Mill both try to explain right and wrong, without a divine lawgiver [Taylor,R] |
| Full Idea: Kant and Mill were in total agreement in trying to give content to the distinction between moral right and wrong, without recourse to any divine lawgiver. | |
| From: Richard Taylor (Virtue Ethics: an Introduction [2002], Ch.14) | |
| A reaction: A nice analysis, in tune with MacIntyre and others, who see such attempts as failures. It is hard, however, to deny the claims of rational principles, or of suffering, in our moral framework. I agree with Taylor's move back to virtue, but it ain't simple. |
| 5067 | Morality based on 'forbid', 'permit' and 'require' implies someone who does these things [Taylor,R] |
| Full Idea: If morality is based on wrong (meaning 'forbidden'), right ('permitted'), and obligatory ('required'), we are led to ask 'Who is it that thus permits, forbids or requires that certain things be done or not done?' | |
| From: Richard Taylor (Virtue Ethics: an Introduction [2002], Ch.2) | |
| A reaction: Clear reinforcement for Nietzsche's attack on conventional morals, which Taylor sees as a relic of medieval religious attitudes. Taylor says Kant offered a non-religious version of the same authority. I agree. Back to the Greek pursuit of excellence! |
| 5079 | Pleasure can have a location, and be momentary, and come and go - but happiness can't [Taylor,R] |
| Full Idea: Pleasures can be located in a particular part of the body, and can be momentary, and come and go, but this is not the case with happiness. | |
| From: Richard Taylor (Virtue Ethics: an Introduction [2002], Ch.16) | |
| A reaction: Probably no one ever thought that pleasure and happiness were actually identical - merely that pleasure is the only cause and source of happiness. These are good objections to that hypothesis. Pleasure simply isn't 'the good'. |
| 5068 | 'Eudaimonia' means 'having a good demon', implying supreme good fortune [Taylor,R] |
| Full Idea: The word 'eudaimonia' means literally 'having a good demon', which is apt, because it suggests some kind of supreme good fortune, of the sort which might be thought of as a bestowal. | |
| From: Richard Taylor (Virtue Ethics: an Introduction [2002], Ch.5) | |
| A reaction: Beware of etymology. This implies that eudaimonia is almost entirely beyond a person's control, but Aristotle doesn't think that. A combination of education and effort can build on some natural gifts to create a fully successful life. |
| 5076 | To Greeks it seemed obvious that the virtue of anything is the perfection of its function [Taylor,R] |
| Full Idea: To the Greeks it seemed obvious that the virtue of anything is the perfection of its function. | |
| From: Richard Taylor (Virtue Ethics: an Introduction [2002], Ch.10) | |
| A reaction: A problem case might be a work of art, but one might reply that there is no obvious perfection there because there is no clear function. For artefacts and organisms the principle seems very good. But 'Is the Cosmos good?' |
| 5077 | The modern idea of obligation seems to have lost the idea of an obligation 'to' something [Taylor,R] |
| Full Idea: In modern moral thinking, obligation is something every responsible person is supposed to have, but it is not an obligation to the state, or society, or humanity, or even to God. It is an obligation standing by itself. | |
| From: Richard Taylor (Virtue Ethics: an Introduction [2002], Ch.12) | |
| A reaction: This nicely pinpoints how some our moral attitudes are relics of religion. Taylor wants a return to virtue, but one could respond by opting for the social contract (with very clear obligations) or Kantian 'contractualism' (answering to rational beings). |
| 5066 | If we are made in God's image, pursuit of excellence is replaced by duty to obey God [Taylor,R] |
| Full Idea: Once people are declared to be images of God, just by virtue of minimal humanity, they have, therefore, no greater individual excellence to aspire to, and their purpose became one of obligation, that is, obedience to God's will. | |
| From: Richard Taylor (Virtue Ethics: an Introduction [2002], Ch.2) | |
| A reaction: An interesting and plausible historical analysis. There is a second motivation for the change, though, in Grotius's desire to develop a more legalistic morality, focusing on actions rather than character. Taylor's point is more interesting, though. |
| 5065 | The ethics of duty requires a religious framework [Taylor,R] |
| Full Idea: The ethics of duty cannot be sustained independently of a religious framework. | |
| From: Richard Taylor (Virtue Ethics: an Introduction [2002], Ch.2) | |
| A reaction: This is a big challenge to Kant, echoing Nietzsche's jibe that Kant just wanted to be 'obedient'. The only options are either 'natural duties', or 'duties of reason'. Reason may have a pull (like pleasure), but a 'duty'? Difficult. |
| 5994 | Is the cosmos open or closed, mechanical or teleological, alive or inanimate, and created or eternal? [Robinson,TM, by PG] |
| Full Idea: The four major disputes in classical cosmology were whether the cosmos is 'open' or 'closed', whether it is explained mechanistically or teleologically, whether it is alive or mere matter, and whether or not it has a beginning. | |
| From: report of T.M. Robinson (Classical Cosmology (frags) [1997]) by PG - Db (ideas) | |
| A reaction: A nice summary. The standard modern view is closed, mechanistic, inanimate and non-eternal. But philosophers can ask deeper questions than physicists, and I say we are entitled to speculate when the evidence runs out. |