27 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. |
| 22227 | For Sartre there is only being for-itself, or being in-itself (which is beyond experience) [Sartre, by Daigle] |
| Full Idea: The two most fundamental modes of being in Sartre's ontology are being in-itself, and being for-itself. ...The in-itself lies beyond our experience of it. | |
| From: report of Jean-Paul Sartre (Being and Nothingness [1943]) by Christine Daigle - Jean-Paul Sartre 2.2 | |
| A reaction: This appears to be Kant's ding-an-sich, paired with Heidegger's Dasein. If those are the only options, then reality is either subjective or unknown, which seems to make Sartre an idealist, but he asserted that phenomena vindicate the in-itself. |
| 20743 | Appearances do not hide the essence; appearances are the essence [Sartre] |
| Full Idea: We reject the dualism of appearance and essence. The appearance does not hide the essence, it reveals it; it is the essence. | |
| From: Jean-Paul Sartre (Being and Nothingness [1943], p.4-5), quoted by Kevin Aho - Existentialism: an introduction 2 'Phenomenology' | |
| A reaction: This idea, expressed in the language of Hegel and Husserl, strikes me as the same as the analytic phenomenalism of Mill and Ayer. Hence I take it to be wrong. |
| 6151 | Sartre says consciousness is just directedness towards external objects [Sartre, by Rowlands] |
| Full Idea: Sartre defends a view of consciousness as nothing but a directedness towards objects, insisting that these objects are transcendent with respect to that consciousness; hence Sartre is one of the first genuine externalists. | |
| From: report of Jean-Paul Sartre (Being and Nothingness [1943]) by Mark Rowlands - Externalism Ch.1 | |
| A reaction: An ancestor here is, I think, Schopenhauer (Idea 4166). The idea is attractive, as we are brought up with idea that we have a thing called 'consciousness', but if you removed its contents there would literally be nothing left. |
| 6164 | Sartre rejects mental content, and the idea that the mind has hidden inner features [Sartre, by Rowlands] |
| Full Idea: Sartre's attack on the idea that consciousness has contents is an attack on the idea that the mental possesses features that are hidden, inner and constituted or revealed by the individual's inwardly directed awareness. | |
| From: report of Jean-Paul Sartre (Being and Nothingness [1943]) by Mark Rowlands - Externalism Ch.5 | |
| A reaction: This is part of the move towards 'externalism' about the mind. The notion of 'content' implies a container. It seems slightly ridiculous, though, to try to say that the mind just 'is the world'. How is reasoning possible, and the relation of ideas? |
| 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. |
| 7074 | Man is a useless passion [Sartre] |
| Full Idea: Man is a useless passion. | |
| From: Jean-Paul Sartre (Being and Nothingness [1943], IV.2.III) | |
| A reaction: Memorable and neat. Since all of existence is ultimately 'useless', that part of it is not a revelation. The notion that we are essentially a 'passion' chimes nicely with David Hume's view, against the enlightenment rational view, and against Aristotle. |
| 6687 | Man is the desire to be God [Sartre] |
| Full Idea: Man fundamentally is the desire to be God. | |
| From: Jean-Paul Sartre (Being and Nothingness [1943], p.556?), quoted by Gordon Graham - Eight Theories of Ethics Ch.5 | |
| A reaction: It is better to see man (as seen all the way through the European tradition) as caught between the self-images of being an angel and being a 'quintessence of dust' (Hamlet). |
| 22228 | Sartre's freedom is not for whimsical action, but taking responsibility for our own values [Sartre, by Daigle] |
| Full Idea: Readers often confuse Sartre's notion of freedom with the freedom of acting whimsically ....but since there is no God, we must create our own values. Freedom is not merely a licence to act whimsically.; it entails responsibility. | |
| From: report of Jean-Paul Sartre (Being and Nothingness [1943]) by Christine Daigle - Jean-Paul Sartre 2.3 | |
| A reaction: The idea that we create our values comes from Nietzsche. Did Sartre want everyone to behave like an übermensch? How can you form a society from individuals who create private values, even if they (somehow) take responsibility for them? |
| 22233 | Love is the demand to be loved [Sartre] |
| Full Idea: Love is the demand to be loved. | |
| From: Jean-Paul Sartre (Being and Nothingness [1943], p.488), quoted by Christine Daigle - Jean-Paul Sartre 2.5 | |
| A reaction: Is that all love is? Hard to imagine someone loving another person without hoping that the other person will reciprocate. You need high self-esteem to 'demand' it. Low self-esteem merely hopes for it. He says the other person may feel the same. |
| 20755 | Fear concerns the world, but 'anguish' comes from confronting my self [Sartre] |
| Full Idea: Anguish is distinguished from fear in that fear is fear of being in the world whereas anguish is anguish before myself. | |
| From: Jean-Paul Sartre (Being and Nothingness [1943], p.65), quoted by Kevin Aho - Existentialism: an introduction 5 'Radical' | |
| A reaction: I'm guessing that the anguish comes from the horror of the infinite choices available to me. Once you've made major life choices with full commitment (such as marriage), does that mean that existentialism becomes irrelevant? |
| 20760 | Sincerity is not authenticity, because it only commits to one particular identity [Sartre, by Aho] |
| Full Idea: Being sincere [in Sartre] has nothing to do with authenticity because, in committing ourselves to a particular identity, we strip away the possibility of transcendence by reducing ourselves to a thing. | |
| From: report of Jean-Paul Sartre (Being and Nothingness [1943]) by Kevin Aho - Existentialism: an introduction 6 'Bad' | |
| A reaction: I take this to mean that sincerity says genuinely what role you are playing (such as a waiter), but authenticity is recognition that you don't have to play that role. I think. |
| 22231 | We flee from the anguish of freedom by seeing ourselves objectively, as determined [Sartre] |
| Full Idea: We are always ready to take refuge in a belief in determinism if this freedom weighs upon us or if we need an excuse. Thus we flee from anguish by attempting to apprehend ourselves from without as an Other or a thing. | |
| From: Jean-Paul Sartre (Being and Nothingness [1943], p.82), quoted by Christine Daigle - Jean-Paul Sartre 2.4 | |
| A reaction: I would have thought we blame social pressures, or biological pressures, rather than metaphysical determinism, but it amounts to the same thing. If we are not free then probably nothing else is. |
| 13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
| Full Idea: In a single day there lies open to men of learning more than there ever does to the unenlightened in the longest of lifetimes. | |
| From: Posidonius (fragments/reports [c.95 BCE]), quoted by Seneca the Younger - Letters from a Stoic 078 | |
| A reaction: These remarks endorsing the infinite superiority of the educated to the uneducated seem to have been popular in late antiquity. It tends to be the religions which discourage great learning, especially in their emphasis on a single book. |
| 20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |
| Full Idea: Posidonius defined time thus: it is an interval of motion, or the measure of speed and slowness. | |
| From: report of Posidonius (fragments/reports [c.95 BCE]) by John Stobaeus - Anthology 1.08.42 | |
| A reaction: Hm. Can we define motion or speed without alluding to time? Looks like we have to define them as a conjoined pair, which means we cannot fully understand either of them. |