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) |
| 20320 | Truth is what unites, and the profound truths create a community [Jaspers] |
| Full Idea: Truth is what unites. ...[p.145] The most profound truth is that which all men might understand so as to form one community. | |
| From: Karl Jaspers (Philosophy [1932], vol.2) | |
| A reaction: Nice slogan, for robust realists like me. The hallmark of truth is our convergence on it. This is a 20th century existentialist perfectly expounding the enlightenment dream. The best rhetoric is truthful rhetoric. |
| 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. |
| 21513 | We can no more expect a precise definition of coherence than we can of the moral ideal [Ewing] |
| Full Idea: I think it is wrong to tie down the advocates of the coherence theory to a precise definition. ...It would be altogether unreasonable to demand that the moral ideal should be exhaustively defined, and the same may be true of the ideal of thought. | |
| From: A.C. Ewing (Idealism: a critical survey [1934], p.231), quoted by Erik J. Olsson - Against Coherence 7.6 | |
| A reaction: I strongly agree. It is not a council of despair. I think the criteria of coherence can be articulated quite well (e.g by Thagard), and the virtues of enquiry can also be quite well specified (e.g. by Zagzebski). Very dissimilar evidence must cohere. |
| 21497 | If undetailed, 'coherence' is just a vague words that covers all possible arguments [Ewing] |
| Full Idea: Without a detailed account, coherence is reduced to the mere muttering of the word 'coherence', which can be interpreted so as to cover all arguments, but only by making its meaning so wide as to rob it of almost all significance. | |
| From: A.C. Ewing (Idealism: a critical survey [1934], p.246), quoted by Erik J. Olsson - Against Coherence 2.2 | |
| A reaction: I'm a fan of coherence, but it is a placeholder, involving no intrinsic or detailed theory. I just think it points to the reality of how we make judgements, especially practical ones. We can categorise the inputs, and explain the required virtues. |
| 20323 | Freedom needs knowledge, the possibility of arbitrariness, and law [Jaspers] |
| Full Idea: Without knowledge there is no freedom ....and without an arbitrary act there is no freedom, ....and there is no freedom without law. | |
| From: Karl Jaspers (Philosophy [1932], vol.2) | |
| A reaction: He emphasises that an arbitrary act is not a free act, but it is a precondition for being free. The submission to law is active freedom. If you believe in education (and you should) you must believe that knowledge is liberating. |
| 20322 | I am aware that freedom is possible, and the freedom is not in theory, but in seeking freedom [Jaspers] |
| Full Idea: Either there is no freedom or it is in asking about it. But what makes me ask is an original will to be free, so my freedom is anticipated in the fact of asking. I cannot prove it first, then will it. I will it because I am conscious of its possibility. | |
| From: Karl Jaspers (Philosophy [1932], vol.2) | |
| A reaction: This presents the subjective claims for free will rather more persuasively than usual. I am conscious of a possibility that I might flap my arms and fly, so that doesn't establish anything. But yearning to be free is a sort of freedom. |
| 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. |
| 20324 | My freedom increases as I broaden my vision of possiblities and motives [Jaspers] |
| Full Idea: I become free by incessantly broadening my worldly orientation, by limitlessly visualising premises and possibilities of action, and by allowing all motives to speak to me. ...The more the totality determines my vision the freer I know I am. | |
| From: Karl Jaspers (Philosophy [1932], vol.2) | |
| A reaction: This matches my naturalistic view of responsibility for actions, which are those performed by the 'full' and knowing self. I note that freedom comes in degrees for him, so he presumably don't believe in absolute freedom. It is wholly subjective. |
| 20318 | My helplessness in philosophising reveals my being, and begins its upsurge [Jaspers] |
| Full Idea: Philosophising, not knowing, brings me to myself. The helplessness to which philosophising reduces me when I doubt its origin is an expressions of the helplessness of my self-being, and the reality of philosophising is the incipient upsurge of that being. | |
| From: Karl Jaspers (Philosophy [1932], vol.2) | |
| A reaction: I like the sound of 'philosophy as a way of life', and loosely aspire to it, but I'm still not sure what it means, other than a good way to pass the time. The idea that it leads to higher modes of being sounds a bit arrogant. But it is a good thing! |
| 20321 | The struggle for Existenz is between people who are equals, and are utterly honest [Jaspers] |
| Full Idea: The struggle for Existenz has to do with ...with utter candour, with the elimination of all kinds of power and superiority, with the other's self-being as well as with my own. | |
| From: Karl Jaspers (Philosophy [1932], vol.2) | |
| A reaction: This is reminiscent of Aristotle's conclusion that democracy is the society which is most conducive to true friendship. I like Jaspers's idea that existential enquiry is a team game. |
| 20325 | Once we grasp freedom 'from' things, then freedom 'for' things becomes urgent [Jaspers] |
| Full Idea: Once the question of 'freedom from what?' has been answered by shattering all objectivities, the question of 'freedom for what?' becomes all the more urgent. | |
| From: Karl Jaspers (Philosophy [1932], vol.2) | |
| A reaction: A quintessential existentialist idea, and its most appealing aspect. Message to all teenagers: don't get bogged down in what you are prevented from doing, but focus on what you can do. The first problem will melt away. (Unless you are in handcuffs....). |
| 20317 | Mundane existence is general, falling under universals, but Existens is unique to individuals [Jaspers] |
| Full Idea: Mundane being, the being we know, is general because it is generally valid for everyone. ...Existenz is never general, and thus not a case that might be subsumed as particular under a universal. | |
| From: Karl Jaspers (Philosophy [1932], vol.2) | |
| A reaction: I'm trying to visualise a mode of existence which would fulfil only me, answering to my unique nature, but it looks like a vain delusion. I may be a one-off combination, but I see all of my ingredients in various other people. |
| 20319 | We want the correct grasp on being that is neither solipsism nor absorption in the crowd [Jaspers] |
| Full Idea: We want our philosophising to illuminate the free, original, communicative grasp on being that will let us meet the constant threat of solipsism or universalism in existence. | |
| From: Karl Jaspers (Philosophy [1932], vol.2) | |
| A reaction: This sounds like the political wing of existentialism: the aim to get the right relationship between citizens - not too withdrawn, and not swallowed in the crowd. Liberal democracy, I should think. |
| 20315 | 'Existenz' is the potential being, which I could have, and ought to have [Jaspers] |
| Full Idea: There is the being which in the phenomenality of existence is not but can be, ought to be, and therefore decides in time whether it is in eternity. This being is myself as 'Existenz'. | |
| From: Karl Jaspers (Philosophy [1932], vol.2) | |
| A reaction: This is quintessentially existentialist, in its claim that my mode of being could be quite other than it is. Personally I aim to fulfil the being I've got. Play the cards you have been dealt. |
| 20316 | Every decision I make moves towards or away from fulfilled Existenz [Jaspers] |
| Full Idea: My Existenz, as a possibility, takes a step toward being or away from being, toward nothingness, in every choice or decision I make. | |
| From: Karl Jaspers (Philosophy [1932], vol.2) | |
| A reaction: The existential idea of action involves what you are, as well as what you do. There seems to be a paradox. My being is plastic, and can change enormously, so I should take responsibility for the change. But who is in charge of the changes? |