26 ideas
17990 | Instances of minimal truth miss out propositions inexpressible in current English [Hofweber] |
Full Idea: A standard objection to minimalist truth is the 'incompleteness objection'. Since there are propositions inexpressible in present English the concept of truth isn't captured by all the instances of the Tarski biconditional. | |
From: Thomas Hofweber (Inexpressible Properties and Propositions [2006], 5.3) | |
A reaction: Sounds like a good objection. |
17884 | Mathematical set theory has many plausible stopping points, such as finitism, and predicativism [Koellner] |
Full Idea: There are many coherent stopping points in the hierarchy of increasingly strong mathematical systems, starting with strict finitism, and moving up through predicativism to the higher reaches of set theory. | |
From: Peter Koellner (On the Question of Absolute Undecidability [2006], Intro) |
17893 | 'Reflection principles' say the whole truth about sets can't be captured [Koellner] |
Full Idea: Roughly speaking, 'reflection principles' assert that anything true in V [the set hierarchy] falls short of characterising V in that it is true within some earlier level. | |
From: Peter Koellner (On the Question of Absolute Undecidability [2006], 2.1) |
17988 | Quantification can't all be substitutional; some reference is obviously to objects [Hofweber] |
Full Idea: The view that all quantification is substitutional is not very plausible in general. Some uses of quantifiers clearly seem to have the function to make a claim about a domain of objects out there, no matter how they relate to the terms in our language. | |
From: Thomas Hofweber (Inexpressible Properties and Propositions [2006], 2.1) | |
A reaction: Robust realists like myself are hardly going to say that quantification is just an internal language game. |
17894 | We have no argument to show a statement is absolutely undecidable [Koellner] |
Full Idea: There is at present no solid argument to the effect that a given statement is absolutely undecidable. | |
From: Peter Koellner (On the Question of Absolute Undecidability [2006], 5.3) |
17890 | There are at least eleven types of large cardinal, of increasing logical strength [Koellner] |
Full Idea: Some of the standard large cardinals (in order of increasing (logical) strength) are: inaccessible, Mahlo, weakly compact, indescribable, Erdös, measurable, strong, Wodin, supercompact, huge etc. (...and ineffable). | |
From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4) | |
A reaction: [I don't understand how cardinals can have 'logical strength', but I pass it on anyway] |
17887 | PA is consistent as far as we can accept, and we expand axioms to overcome limitations [Koellner] |
Full Idea: To the extent that we are justified in accepting Peano Arithmetic we are justified in accepting its consistency, and so we know how to expand the axiom system so as to overcome the limitation [of Gödel's Second Theorem]. | |
From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.1) | |
A reaction: Each expansion brings a limitation, but then you can expand again. |
17891 | Arithmetical undecidability is always settled at the next stage up [Koellner] |
Full Idea: The arithmetical instances of undecidability that arise at one stage of the hierarchy are settled at the next. | |
From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4) |
17989 | Since properties have properties, there can be a typed or a type-free theory of them [Hofweber] |
Full Idea: Since properties themselves can have properties there is a well-known division in the theory of properties between those who take a typed and those who take a type-free approach. | |
From: Thomas Hofweber (Inexpressible Properties and Propositions [2006], 2.2) | |
A reaction: A typed approach would imply restrictions on what it can be a property of. 'Green' is a property of surfaces, 'dark' is a property of colours. My first reaction is to opt for type-free. |
8780 | Attributes are functions, not objects; this distinguishes 'square of 2' from 'double of 2' [Geach] |
Full Idea: Attributes should not be thought of as identifiable objects. It is better to follow Frege and compare them to mathematical functions. 'Square of' and 'double of' x are distinct functions, even though they are not distinguishable in thought when x is 2. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §11) | |
A reaction: Attributes are features of the world, of which animals are well aware, and the mathematical model is dubious when dealing with physical properties. The route to arriving at 2 is not the same concept as 2. There are many roads to Rome. |
11910 | Being 'the same' is meaningless, unless we specify 'the same X' [Geach] |
Full Idea: "The same" is a fragmentary expression, and has no significance unless we say or mean "the same X", where X represents a general term. ...There is no such thing as being just 'the same'. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §16) | |
A reaction: Geach seems oddly unaware of the perfect identity of Hespherus with Phosphorus. His critics don't spot that he was concerned with identity over time (of 'the same man', who ages). Perry's critique emphasises the type/token distinction. |
8775 | A big flea is a small animal, so 'big' and 'small' cannot be acquired by abstraction [Geach] |
Full Idea: A big flea or rat is a small animal, and a small elephant is a big animal, so there can be no question of ignoring the kind of thing to which 'big' or 'small' is referred and forming those concepts by abstraction. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §9) | |
A reaction: Geach is attacking a caricature of the theory. Abstraction is a neat mental trick which has developed in stages, from big rats relative to us, to big relative to other rats, to the concept of 'relative' (Idea 8776!), to the concept of 'relative bigness'. |
8776 | We cannot learn relations by abstraction, because their converse must be learned too [Geach] |
Full Idea: Abstractionists are unaware of the difficulty with relations - that they neither exist nor can be observed apart from the converse relation, the two being indivisible, as in grasping 'to the left of' and 'to the right of'. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §9) | |
A reaction: It is hard to see how a rival account such as platonism could help. It seems obvious to me that 'right' and 'left' would be quite meaningless without some experience of things in space, including an orientation to them. |
2567 | You can't define real mental states in terms of behaviour that never happens [Geach] |
Full Idea: We can't take a statement that two men, whose overt behaviour was not actually different, were in different states of mind as being really a statement that the behaviour of one man would have been different in hypothetical circumstances that never arose. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §3) | |
A reaction: This is the whole problem with trying to define the mind as dispositions. The same might be said of properties, since some properties are active, but others are mere potential or disposition. Hence 'process' looks to me the most promising word for mind. |
2568 | Beliefs aren't tied to particular behaviours [Geach] |
Full Idea: Is there any behaviour characteristic of a given belief? | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §4) | |
A reaction: Well, yes. Belief that a dog is about to bite you. Belief that this nice food is yours, and you are hungry. But he has a good point. He is pointing out that the mental state is a very different thing from the 'disposition' to behave in a certain way. |
8781 | The mind does not lift concepts from experience; it creates them, and then applies them [Geach] |
Full Idea: Having a concept is not recognizing a feature of experience; the mind makes concepts. We then fit our concepts to experience. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §11) | |
A reaction: This seems to imply that we create concepts ex nihilo, which is a rather worse theory than saying that we abstract them from multiple (and multi-level) experiences. That minds create concepts is a truism. How do we do it? |
8769 | If someone has aphasia but can still play chess, they clearly have concepts [Geach] |
Full Idea: If a man struck with aphasia can still play bridge or chess, I certainly wish to say he still has the concepts involved in the game, although he can no longer exercise them verbally. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §5) | |
A reaction: Geach proceeds thereafter to concentrate on language, but this caveat is crucial. To suggest that concepts are entirely verbal has always struck me as ridiculous, and an insult to our inarticulate mammalian cousins. |
8770 | 'Abstractionism' is acquiring a concept by picking out one experience amongst a group [Geach] |
Full Idea: I call 'abstractionism' the doctrine that a concept is acquired by a process of singling out in attention some one feature given in direct experience - abstracting it - and ignoring the other features simultaneously given - abstracting from them. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §6) | |
A reaction: Locke seems to be the best known ancestor of this view, and Geach launches a vigorous attack against it. However, contemporary philosophers still refer to the process, and I think Geach should be crushed and this theory revived. |
8771 | 'Or' and 'not' are not to be found in the sensible world, or even in the world of inner experience [Geach] |
Full Idea: Nowhere in the sensible world could you find anything to be suitably labelled 'or' or 'not'. So the abstractionist appeals to an 'inner sense', or hesitation for 'or', and of frustration or inhibition for 'not'. Personally I see a threat in 'or else'! | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §7) | |
A reaction: This is a key argument of Geach's against abstractionism. As a logician he prefers to discuss connectives rather than, say, colours. I think they might be meta-abstractions, which you create internally once you have picked up the knack. |
8772 | We can't acquire number-concepts by extracting the number from the things being counted [Geach] |
Full Idea: The number-concepts just cannot be got by concentrating on the number and abstracting from the kind of things being counted. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §8) | |
A reaction: This point is from Frege - that if you 'abstract away' everything apart from the number, you are simply left with nothing in experience. The objection might, I think, be met by viewing it as second-order abstraction, perhaps getting to a pattern first. |
8773 | Abstractionists can't explain counting, because it must precede experience of objects [Geach] |
Full Idea: The way counting is learned is wholly contrary to abstractionist preconceptions, because the series of numerals has to be learned before it can be applied. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §8) | |
A reaction: You might learn to parrot the names of numbers, but you could hardly know what they meant if you couldn't count anything. See Idea 3907. I would have thought that individuating objects must logically and pedagogically precede counting. |
8774 | The numbers don't exist in nature, so they cannot have been abstracted from there into our languages [Geach] |
Full Idea: The pattern of the numeral series that is grasped by a child exists nowhere in nature outside human languages, so the human race cannot possibly have discerned this pattern by abstracting it from some natural context. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §8) | |
A reaction: This is a spectacular non sequitur, which begs the question. Abstractionists precisely claim that the process of abstraction brings numerals into human language from the natural context. Structuralism is an attempt to explain the process. |
8778 | Blind people can use colour words like 'red' perfectly intelligently [Geach] |
Full Idea: It is not true that men born blind can form no colour-concepts; a man born blind can use the word 'red' with a considerable measure of intelligence; he can show a practical grasp of the logic of the word. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §10) | |
A reaction: Weak. It is obvious that they pick up the word 'red' from the usage of sighted people, and the usage of the word doesn't guarantee a grasp of the concept, as when non-mathematicians refer to 'calculus'. Compare Idea 7377 and Idea 7866. |
8777 | If 'black' and 'cat' can be used in the absence of such objects, how can such usage be abstracted? [Geach] |
Full Idea: Since we can use the terms 'black' and 'cat' in situations not including any black object or any cat, how could this part of the use be got by abstraction? | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §10) | |
A reaction: [He is attacking H.H. Price] It doesn't seem a huge psychological leap to apply the word 'cat' when we remember a cat, and once it is in the mind we can play games with our abstractions. Cats are smaller than dogs. |
8779 | We can form two different abstract concepts that apply to a single unified experience [Geach] |
Full Idea: It is impossible to form the concept of 'chromatic colour' by discriminative attention to a feature given in my visual experience. In seeing a red window-pane, I do not have two sensations, one of redness and one of chromatic colour. | |
From: Peter Geach (Mental Acts: their content and their objects [1957], §10) | |
A reaction: Again Geach begs the question, because abstractionists claim that you can focus on two different 'aspects' of the one experience, as that it is a 'window', or it is 'red', or it is not a wall, or it is not monochrome. |
17991 | Holism says language can't be translated; the expressibility hypothesis says everything can [Hofweber] |
Full Idea: Holism says that nothing that can be said in one language can be said in another one. The expressibility hypothesis says that everything that can be said in one language can be said in every other one. | |
From: Thomas Hofweber (Inexpressible Properties and Propositions [2006], 6.4) | |
A reaction: Obviously expressibility would only refer to reasonably comprehensive languages (with basic logical connectives, for example). Personally I vote for the expressibility hypothesis, which Hofweber seems to favour. |