31 ideas
4739 | In "if and only if" (iff), "if" expresses the sufficient condition, and "only if" the necessary condition [Engel] |
Full Idea: Necessary and sufficient conditions are usually expressed by "if and only if" (abbr. "iff"), where "if" is the sufficient condition, and "only if" is the necessary condition. | |
From: Pascal Engel (Truth [2002], §1.1) | |
A reaction: 'I take my umbrella if and only if it is raining' (oh, and if I'm still alive). There may be other necessary conditions than the one specified. Oh, and I take it if my wife slips it into my car… |
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) |
4737 | Are truth-bearers propositions, or ideas/beliefs, or sentences/utterances? [Engel] |
Full Idea: The tradition of the Stoics and Frege says that truth-bearers are propositions, Descartes and the classical empiricist say they are ideas or beliefs, and Ockham and Quine say they are sentences or utterances. | |
From: Pascal Engel (Truth [2002], §1.1) | |
A reaction: I'm with propositions, which are unambiguous, can be expressed in a variety of ways, embody the 'logical form' of sentences, and could be physically embodied in brains (the language of thought?). |
4750 | The redundancy theory gets rid of facts, for 'it is a fact that p' just means 'p' [Engel] |
Full Idea: The redundancy theory gets rid of facts, for 'it is a fact that p' just means 'p'. | |
From: Pascal Engel (Truth [2002], §2.2) | |
A reaction: But then when you ask what p means, you have to give the truth-conditions for its assertion, and you find you have to mention the facts after all. |
4744 | We can't explain the corresponding structure of the world except by referring to our thoughts [Engel] |
Full Idea: The correspondence theory implies displaying an identity or similarity of structure between the contents of thoughts and the way the world is structured, but we seem only to be able to say that the world's structure corresponds to our thoughts. | |
From: Pascal Engel (Truth [2002], §1.2) | |
A reaction: I don't accept this. The structure of the world gives rise to our thoughts. There is an epistemological problem here (big time!), but that doesn't alter the metaphysical situation of what truth is supposed to be, which is correspondence. |
4738 | The coherence theory says truth is an internal relationship between groups of truth-bearers [Engel] |
Full Idea: The coherence theory of truth says that it is a relationship between truth-bearers themselves, that is between propositions or beliefs or sentences. | |
From: Pascal Engel (Truth [2002], §1.1) | |
A reaction: We immediately begin to wonder how many truth-bearers are required. Two lies can be coherent. It is hard to make thousands of lies coherent, but not impossible. What fixes the critical number. 'All possible propositions' is not much help. |
4745 | Any coherent set of beliefs can be made more coherent by adding some false beliefs [Engel] |
Full Idea: Any coherent set of beliefs can be made more coherent by adding to it one or more false beliefs. | |
From: Pascal Engel (Truth [2002], §1.3) | |
A reaction: A simple but rather devastating point. It is the policeman manufacturing a bogus piece of evidence to clinch the conviction, the scientist faking a single observation to fill in the last corner of a promising theory. |
4755 | Deflationism cannot explain why we hold beliefs for reasons [Engel] |
Full Idea: The deflationist view is silent about the fact that our assertions and beliefs are generally made or held for certain reasons. | |
From: Pascal Engel (Truth [2002], §2.5) | |
A reaction: The point here must be that I attribute strength to my beliefs, depending on how much support I have for them - how much support for their real truth. I scream "That's really TRUE!" when I have very good reasons. |
4753 | Deflationism seems to block philosophers' main occupation, asking metatheoretical questions [Engel] |
Full Idea: Deflationism about truth seems to deprive us of any hope of asking genuinely metatheoretical questions, which are the questions that occupy philosophers most of the time. | |
From: Pascal Engel (Truth [2002], §2.5) | |
A reaction: This seems like the best reason for moving from deflationism to at least minimalism. Clearly one can talk meaningfully about the success of assertions and theories. You can say a sentence is true, but not assert it. |
4751 | Maybe there is no more to be said about 'true' than there is about the function of 'and' in logic [Engel] |
Full Idea: We could compare the status of 'true' with the status of the logical operator 'and' in logic. Once we have explained how it functions to conjoin two propositions, there is not much more to be said about it. | |
From: Pascal Engel (Truth [2002], §2.4) | |
A reaction: A good statement of the minimalist view. I don't believe it, because I don't believe that truth is confined to language. An uneasy feeling I can't put into words can turn out to be true. Truth is a relational feature of mental states. |
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. |
4752 | Deflationism must reduce bivalence ('p is true or false') to excluded middle ('p or not-p') [Engel] |
Full Idea: It is said that deflationism cannot even formulate the principle of bivalence, for 'either p is true or p is false' will amount to the principle of excluded middle, 'either p or not-p'. | |
From: Pascal Engel (Truth [2002], §2.4) | |
A reaction: Presumably deflationists don't lost any sleep over this - in fact, it looks like a good concise way to state the deflationist thesis. However, excluded middle refers to a proposition (not-p) that was never mentioned by bivalence. Cf Idea 6163. |
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. |
4762 | The Humean theory of motivation is that beliefs may be motivators as well as desires [Engel] |
Full Idea: A problem for the Humean theory of motivation is that it is disputed that beliefs are only representational states, which cannot, unlike desires, move us to act. | |
From: Pascal Engel (Truth [2002], §4.2) | |
A reaction: This is a crucial issue for Humeans and empiricists. Rationalists claim that people act for reasons, so that reasons are intrinsically motivational (like the Form of the Good), and reasons may even be considered direct causes of actions. |
4754 | Our beliefs are meant to fit the world (i.e. be true), where we want the world to fit our desires [Engel] |
Full Idea: Belief is said to 'aim at truth', in the sense that beliefs are the kind of mental states that have to be true for the mind to 'fit' the world (where our desires have the opposite 'direction of fit'; the world is supposed to fit our desires). | |
From: Pascal Engel (Truth [2002], §2.5) | |
A reaction: I don't think it is possible to give a plausible definition of belief without mentioning truth. Hume's account of them as thoughts with a funny feeling attached is ridiculous. Thinking is an activity, not a passive state. |
4763 | 'Evidentialists' say, and 'voluntarists' deny, that we only believe on the basis of evidence [Engel] |
Full Idea: The 'evidentialists' (such as Locke and Hume) deny, and the 'voluntarists' (such as William James) affirm, that we ought to, or at least may, believe for other reasons than evidential epistemic reasons (e.g. for pragmatic reasons). | |
From: Pascal Engel (Truth [2002], §5.2) | |
A reaction: No need to be black-or-white here. Blatant evidence compels belief, but we may also come to believe by spotting a coherence, without additional evidence. We can also be in a state of trying to believe something. But see 4764. |
4746 | Pragmatism is better understood as a theory of belief than as a theory of truth [Engel] |
Full Idea: Pragmatism in general is better construed as a certain conception of belief, rather than as a distinctive conception of truth. | |
From: Pascal Engel (Truth [2002], §1.5) | |
A reaction: Which is why aspiring relativists drift towards the pragmatic theory - because they want to dispense with truth (and hence knowledge), and put mere belief in its place. |
4764 | We cannot directly control our beliefs, but we can control the causes of our involuntary beliefs [Engel] |
Full Idea: Direct psychological voluntarism about beliefs seems to be false, but we can have an indirect voluntary control on many of our beliefs, by manipulating the states in us that are involuntary and which lead to certain beliefs. | |
From: Pascal Engel (Truth [2002], §5.2) | |
A reaction: Very nice! This points two ways - to scientific experiments, which can have compelling outcomes (see Fodor), and to brain-washing, and especially auto-brainwashing (only reading articles which support your favourites theories). What magazines do you take? |
1556 | By nature people are close to one another, but culture drives them apart [Hippias] |
Full Idea: I regard you all as relatives - by nature, not by convention. By nature like is akin to like, but convention is a tyrant over humankind and often constrains people to act contrary to nature. | |
From: Hippias (fragments/reports [c.430 BCE]), quoted by Plato - Protagoras 337c8 |
4759 | Mental states as functions are second-order properties, realised by first-order physical properties [Engel] |
Full Idea: For functionalism mental states as roles are second-order properties that have to be realised in various ways in first-order physical properties. | |
From: Pascal Engel (Truth [2002], §3.3) | |
A reaction: I take that to be properties-of-properties, as in 'bright red' or 'poignantly beautiful'. I am inclined to think (with Edelman) that mind is a process, not a property. |
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. |