48 ideas
| 3099 | Inference is never a conscious process [Harman] |
| Full Idea: Inference is never a conscious process. | |
| From: Gilbert Harman (Thought [1973], 11.2) |
| 3077 | Reasoning might be defined in terms of its functional role, which is to produce knowledge [Harman] |
| Full Idea: Reasoning could be treated as a functionally defined process that is partly defined in terms of its role in giving a person knowledge. | |
| From: Gilbert Harman (Thought [1973], 3.6) |
| 3092 | If you believe that some of your beliefs are false, then at least one of your beliefs IS false [Harman] |
| Full Idea: If a rational man believes he has at least some other false beliefs, it follows that a rational man knows that at least one of his beliefs is false (the one believed false, or this new belief). | |
| From: Gilbert Harman (Thought [1973], 7.2) |
| 7786 | Propositional logic handles negation, disjunction, conjunction; predicate logic adds quantifiers, predicates, relations [Girle] |
| Full Idea: Propositional logic can deal with negation, disjunction and conjunction of propositions, but predicate logic goes beyond it to deal with quantifiers, predicates and relations. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 1.1) | |
| A reaction: This is on the first page of an introduction to the next stage, which is to include modal notions like 'must' and 'possibly'. |
| 7798 | There are three axiom schemas for propositional logic [Girle] |
| Full Idea: The axioms of propositional logic are: A→(B→A); A→(B→C)→(A→B)→(A→C) ; and (¬A→¬B)→(B→A). | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 6.5) |
| 7799 | Proposition logic has definitions for its three operators: or, and, and identical [Girle] |
| Full Idea: The operators of propositional logic are defined as follows: 'or' (v) is not-A implies B; 'and' (ampersand) is not A-implies-not-B; and 'identity' (three line equals) is A-implies-B and B-implies-A. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 6.5) |
| 7797 | Axiom systems of logic contain axioms, inference rules, and definitions of proof and theorems [Girle] |
| Full Idea: An axiom system for a logic contains three elements: a set of axioms; a set of inference rules; and definitions for proofs and theorems. There are also definitions for the derivation of conclusions from sets of premises. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 6.5) |
| 7794 | There are seven modalities in S4, each with its negation [Girle] |
| Full Idea: In S4 there are fourteen modalities: no-operator; necessarily; possibly; necessarily-possibly; possibly-necessarily; necessarily-possibly-necessarily; and possibly-necessarily-possibly (each with its negation). | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 3.5) | |
| A reaction: This is said to be 'more complex' than S5, but also 'weaker'. |
| 7793 | ◊p → □◊p is the hallmark of S5 [Girle] |
| Full Idea: The critical formula that distinguishes S5 from all others is: ◊p → □◊p. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 3.3) | |
| A reaction: If it is possible that it is raining, then it is necessary that it is possible that it is raining. But if it is possible in this world, how can that possibility be necessary in all possible worlds? |
| 7795 | S5 has just six modalities, and all strings can be reduced to those [Girle] |
| Full Idea: In S5 there are six modalities: no-operator; necessarily; and possibly (and their negations). In any sequence of operators we may delete all but the last to gain an equivalent formula. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 3.5) | |
| A reaction: Such drastic simplification seems attractive. Is there really no difference, though, between 'necessarily-possibly', 'possibly-possibly' and just 'possibly'? Could p be contingently possible in this world, and necessarily possible in another? |
| 7787 | Possible worlds logics use true-in-a-world rather than true [Girle] |
| Full Idea: In possible worlds logics a statement is true-in-a-world rather than just true. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 1.1) | |
| A reaction: This sounds relativist, but I don't think it is. It is the facts which change, not the concept of truth. So 'donkeys can talk' may be true in a world, but not in the actual one. |
| 7788 | Modal logic has four basic modal negation equivalences [Girle] |
| Full Idea: The four important logical equivalences in modal logic (the Modal Negation equivalences) are: ¬◊p↔□¬p, ◊¬p↔¬□p, □p↔¬◊¬p, and ◊p↔¬□¬p. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 1.2) | |
| A reaction: [Possibly is written as a diamond, necessarily a square] These are parallel to a set of equivalences between quantifiers in predicate logic. They are called the four 'modal negation (MN) equivalences'. |
| 7796 | Modal logics were studied in terms of axioms, but now possible worlds semantics is added [Girle] |
| Full Idea: Modal logics were, for a long time, studied in terms of axiom systems. The advent of possible worlds semantics made it possible to study them in a semantic way as well. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 6.5) |
| 3093 | Any two states are logically linked, by being entailed by their conjunction [Harman] |
| Full Idea: Any two states of affairs are logically connected, simply because both are entailed by their conjunction. | |
| From: Gilbert Harman (Thought [1973], 8.1) |
| 3098 | Deductive logic is the only logic there is [Harman] |
| Full Idea: Deductive logic is the only logic there is. | |
| From: Gilbert Harman (Thought [1973], 10.4) |
| 3094 | You don't have to accept the conclusion of a valid argument [Harman] |
| Full Idea: We may say "From P and If-P-then-Q, infer Q" (modus ponens), but there is no rule of acceptance to say that we should accept Q. Maybe we should stop believing P or If-P-then-Q rather than believe Q. | |
| From: Gilbert Harman (Thought [1973], 10.1) |
| 7789 | Necessary implication is called 'strict implication'; if successful, it is called 'entailment' [Girle] |
| Full Idea: Necessary implication is often called 'strict implication'. The sort of strict implication found in valid arguments, where the conjunction of the premises necessarily implies the conclusion, is often called 'entailment'. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 1.2) | |
| A reaction: These are basic concept for all logic. |
| 3080 | Logical form is the part of a sentence structure which involves logical elements [Harman] |
| Full Idea: The logical form of a sentence is that part of its structure that involves logical elements. | |
| From: Gilbert Harman (Thought [1973], 5.2) |
| 3081 | A theory of truth in a language must involve a theory of logical form [Harman] |
| Full Idea: Some sort of theory of logical form is involved in any theory of truth for a natural language. | |
| From: Gilbert Harman (Thought [1973], 5.2) |
| 3084 | Our underlying predicates represent words in the language, not universal concepts [Harman] |
| Full Idea: The underlying truth-conditional structures of thoughts are language-dependent in the sense that underlying predicates represent words in the language rather than universal concepts common to all languages. | |
| From: Gilbert Harman (Thought [1973], 6.3) |
| 7790 | If an argument is invalid, a truth tree will indicate a counter-example [Girle] |
| Full Idea: The truth trees method for establishing the validity of arguments and formulas is easy to use, and has the advantage that if an argument or formula is not valid, then a counter-example can be retrieved from the tree. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 1.4) |
| 10580 | Mathematics is both necessary and a priori because it really consists of logical truths [Yablo] |
| Full Idea: Mathematics seems necessary because the real contents of mathematical statements are logical truths, which are necessary, and it seems a priori because logical truths really are a priori. | |
| From: Stephen Yablo (Abstract Objects: a Case Study [2002], 10) | |
| A reaction: Yablo says his logicism has a Kantian strain, because numbers and sets 'inscribed on our spectacles', but he takes a different view (in the present Idea) from Kant about where the necessity resides. Personally I am tempted by an a posteriori necessity. |
| 10579 | Putting numbers in quantifiable position (rather than many quantifiers) makes expression easier [Yablo] |
| Full Idea: Saying 'the number of Fs is 5', instead of using five quantifiers, puts the numeral in quantifiable position, which brings expressive advantages. 'There are more sheep in the field than cows' is an infinite disjunction, expressible in finite compass. | |
| From: Stephen Yablo (Abstract Objects: a Case Study [2002], 08) | |
| A reaction: See Hofweber with similar thoughts. This idea I take to be a key one in explaining many metaphysical confusions. The human mind just has a strong tendency to objectify properties, relations, qualities, categories etc. - for expression and for reasoning. |
| 10577 | Concrete objects have few essential properties, but properties of abstractions are mostly essential [Yablo] |
| Full Idea: Objects like me have a few essential properties, and numerous accidental ones. Abstract objects are a different story. The intrinsic properties of the empty set are mostly essential. The relations of numbers are also mostly essential. | |
| From: Stephen Yablo (Abstract Objects: a Case Study [2002], 01) |
| 10578 | We are thought to know concreta a posteriori, and many abstracta a priori [Yablo] |
| Full Idea: Our knowledge of concreta is a posteriori, but our knowledge of numbers, at least, has often been considered a priori. | |
| From: Stephen Yablo (Abstract Objects: a Case Study [2002], 02) |
| 7800 | Analytic truths are divided into logically and conceptually necessary [Girle] |
| Full Idea: It has been customary to see analytic truths as dividing into the logically necessary and the conceptually necessary. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 7.3) | |
| A reaction: I suspect that this neglected distinction is important in discussions of Quine's elimination of the analytic/synthetic distinction. Was Quine too influenced by what is logically necessary, which might shift with a change of axioms? |
| 7801 | Possibilities can be logical, theoretical, physical, economic or human [Girle] |
| Full Idea: Qualified modalities seem to form a hierarchy, if we say that 'the possibility that there might be no hunger' is possible logically, theoretically, physically, economically, and humanly. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 7.3) | |
| A reaction: Girle also mentions conceptual possibility. I take 'physically' to be the same as 'naturally'. I would take 'metaphysically' possible to equate to 'theoretically' rather than 'logically'. Almost anything might be logically possible, with bizarre logic. |
| 7792 | A world has 'access' to a world it generates, which is important in possible worlds semantics [Girle] |
| Full Idea: When one world generates another then it has 'access' to the world it generated. The accessibility relation between worlds is very important in possible worlds semantics. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 3.2) | |
| A reaction: This invites the obvious question what is meant by 'generates'. |
| 3100 | You have to reaffirm all your beliefs when you make a logical inference [Harman] |
| Full Idea: Since inference is inference to the best total account, all your prior beliefs are relevant and your conclusion is everything you believe at the end. So, you constantly reaffirm your beliefs in inference. | |
| From: Gilbert Harman (Thought [1973], 12.1) |
| 3089 | Only lack of imagination makes us think that 'cats are animals' is analytic [Harman] |
| Full Idea: That 'cats are animals' is often cited as an analytic truth. But (as Putnam points out) the inability to imagine this false is just a lack of imagination. They might turn out to be radio-controlled plastic spies from Mars. | |
| From: Gilbert Harman (Thought [1973], 6.7) |
| 3088 | Analyticity is postulated because we can't imagine some things being true, but we may just lack imagination [Harman] |
| Full Idea: Analyticity is postulated to explain why we cannot imagine certain things being true. A better postulate is that we are not good at imagining things. | |
| From: Gilbert Harman (Thought [1973], 6.7) |
| 3101 | Memories are not just preserved, they are constantly reinferred [Harman] |
| Full Idea: I favour the inferential view of memory over the preservation view. …One constantly reinfers old beliefs. | |
| From: Gilbert Harman (Thought [1973], 12.1) | |
| A reaction: This has a grain of truth, but seems a distortion. An image of the old home floats into my mind when I am thinking about something utterly unconnected. When we search memory we may be inferring and explaining, but the same applies to searching images. |
| 3074 | People's reasons for belief are rarely conscious [Harman] |
| Full Idea: The reasons for which people believe things are rarely conscious. | |
| From: Gilbert Harman (Thought [1973], 2.2) | |
| A reaction: Probably correct. The interesting bit is when they bring the beliefs into consciousness and scrutinise them rationally. Philosophers routinely overthrow their natural beliefs in this way. |
| 3097 | We don't distinguish between accepting, and accepting as evidence [Harman] |
| Full Idea: There is no distinction between what we accept as evidence and whatever else we accept. | |
| From: Gilbert Harman (Thought [1973], 10.4) |
| 6369 | In negative coherence theories, beliefs are prima facie justified, and don't need initial reasons [Harman, by Pollock/Cruz] |
| Full Idea: According to Harman's negative coherence theory it is always permissible to adopt a new belief - any new belief; because beliefs are prima facie justified you do not need a reason for adopting a new belief. | |
| From: report of Gilbert Harman (Thought [1973]) by J Pollock / J Cruz - Contemporary theories of Knowledge (2nd) §3.4.1 | |
| A reaction: This must be placed alongside the fact that we don't usually choose our beliefs, but simply find ourselves believing because of the causal impact of evidence. This gives an unstated rational justification for any belief - something caused it. |
| 3096 | Coherence avoids scepticism, because it doesn't rely on unprovable foundations [Harman] |
| Full Idea: Scepticism is undermined once it is seen that the relevant kind of justification is not a matter of derivation from basic principles but is rather a matter of showing that a view fits in well with other things we believe. | |
| From: Gilbert Harman (Thought [1973], 10.4) | |
| A reaction: I would (now) call myself a 'coherentist' about justification, and I agree with this. Coherent justification could not possibly deliver certainty, so it must be combined with fallibilism. |
| 3095 | Induction is an attempt to increase the coherence of our explanations [Harman] |
| Full Idea: Induction is an attempt to increase the explanatory coherence of our view, making it more complete, less ad hoc, more plausible. | |
| From: Gilbert Harman (Thought [1973], 10.2) |
| 3073 | We see ourselves in the world as a map [Harman] |
| Full Idea: Our conception of ourselves in the world is more like a map than a story. | |
| From: Gilbert Harman (Thought [1973], Pref) | |
| A reaction: Dennett offer the 'story' view of the self (Ideas 7381 and 7382). How do we arbitrate this one? A story IS a sort of map. Maps can extend over time as well over space. I think the self is real, and is a location on a map, and the hero of a story. |
| 3076 | Defining dispositions is circular [Harman] |
| Full Idea: There is no noncircular way to specify dispositions; for they are dispositions to behave given certain situations, and the situations must be include beliefs about the situation, and desires concerning it. | |
| From: Gilbert Harman (Thought [1973], 3.3) | |
| A reaction: This is nowadays accepted dogmatically as the biggest objection to behaviourism, but it could be challenged. Your analysis may begin by mentioning beliefs and desires, but if you keep going they may eventually fade out of the picture. |
| 3075 | Could a cloud have a headache if its particles formed into the right pattern? [Harman] |
| Full Idea: If the right pattern of electrical discharges occurred in a cloud instead of in a brain, would that also be a headache? | |
| From: Gilbert Harman (Thought [1973], 3.2) | |
| A reaction: The standard objection to functionalism is to propose absurd implementations of a mind, but probably only a brain could produce the right electro-chemical combination. |
| 3086 | Are there any meanings apart from in a language? [Harman] |
| Full Idea: The theory of language-independent meanings or semantic representations is mistaken. | |
| From: Gilbert Harman (Thought [1973], 6.5) | |
| A reaction: This would make him (in Dummett's terms) a 'philosopher of language' rather than a 'philosopher of thought'. Personally I disagree. Don't animals have 'meanings'? Can two sentences share a meaning? |
| 3078 | Speech acts, communication, representation and truth form a single theory [Harman] |
| Full Idea: The various theories are not in competition. The theory of truth is part of the theory of representational character, which is presupposed by the theory of communication, which in turn is contained in the more general theory of speech acts. | |
| From: Gilbert Harman (Thought [1973], 4.3) | |
| A reaction: Certainly it seems that the supposed major contenders for a theory of meaning are just as much complements as they are competitors. |
| 3090 | There is only similarity in meaning, never sameness in meaning [Harman] |
| Full Idea: The only sort of sameness of meaning we know is similarity in meaning, not exact sameness of meaning. | |
| From: Gilbert Harman (Thought [1973], 6.8) | |
| A reaction: The Eiffel Tower and le tour Eiffel? If you want to be difficult, you can doubt whether the word 'fast' ever has exactly the same meaning in two separate usages of the word. |
| 3082 | Ambiguity is when different underlying truth-conditional structures have the same surface form [Harman] |
| Full Idea: Ambiguity results from the possibility of transforming different underlying truth-conditional structures into the same surface form. | |
| From: Gilbert Harman (Thought [1973], 5.3) | |
| A reaction: Personally I would call a 'truth-conditional structure' a 'proposition', and leave it to the philosophers to decide what a proposition is. |
| 3079 | Truth in a language is explained by how the structural elements of a sentence contribute to its truth conditions [Harman] |
| Full Idea: A theory of truth for a language shows how the truth conditions of any sentence depend on the structure of that sentence. The theory will say, for each element of structure, what its contribution is. | |
| From: Gilbert Harman (Thought [1973], 5.1) | |
| A reaction: This just seems to push the problem of truth back a stage, as you need to know where the truth is to be found in the elements from which the structure is built. |
| 3085 | Sentences are different from propositions, since two sentences can express one proposition [Harman] |
| Full Idea: 'Bob and John play golf' and 'John and Bob play golf' are equivalent; but if they were to be derived from the same underlying structure, one or the other of Bob and John would have to come first; and either possibility is arbitrary. | |
| From: Gilbert Harman (Thought [1973], 6.4) | |
| A reaction: If I watch Bob and John play golf, neither of them 'comes first'. A proposition about them need not involve 'coming first'. Only if you insist on formulating a sentence must you decide on that. |
| 3087 | The analytic/synthetic distinction is a silly division of thought into encyclopaedia and dictionary [Harman] |
| Full Idea: No purpose is served by thinking that certain principles available to a person are contained in his internal encyclopaedia - and therefore only synthetic - whereas other principles are part of his internal dictionary - and are therefore analytic. | |
| From: Gilbert Harman (Thought [1973], 6.5) | |
| A reaction: If it led to two different ways to acquire knowledge, then quite a lot of purpose would be served. He speaks like a pragmatist. The question is whether some statements just are true because of some feature of meaning. Why not? |
| 3083 | Many predicates totally resist translation, so a universal underlying structure to languages is unlikely [Harman] |
| Full Idea: There are many predicates of a given language that resist translation into another language, …so it is unlikely that there is a basic set of underlying structures common to all languages. | |
| From: Gilbert Harman (Thought [1973], 5.4) | |
| A reaction: Not convincing. 'Structures' are not the same as 'predicates'. Once a language has mapped its predicates, that blocks the intrusions of differently sliced alien predicates. No gaps. |