25 ideas
| 18274 | Analysis complicates a statement, but only as far as the complexity of its meaning [Wittgenstein] |
| Full Idea: Analysis makes the statement more complicated than it was; but it cannot and ought not to make it more complicated than its meaning (Bedeutung) was to begin with. When the statement is as complex as its meaning, then it is completely analysed. | |
| From: Ludwig Wittgenstein (Notebooks 1914-1916 [1915], 46e) | |
| A reaction: But how do you assess how complex the 'Bedeutung' was before you started? |
| 4901 | Truth has to be correspondence to facts, and a match between relations of ideas and relations in the world [Perry] |
| Full Idea: I think knowledge and truth are a matter of correspondence to facts, despite all the energy spent showing the naïveté of this view. The connections of our ideas in our heads correspond to relations in the outside world. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §8.1) | |
| A reaction: Yes. Modern books offer the difficulties of defining 'correspondence', and finding an independent account of 'facts', as conclusive objections, but I say a brain is a truth machine, and it had better be useful. Indefinability doesn't nullify concepts. |
| 16908 | We can dispense with self-evidence, if language itself prevents logical mistakes [Jeshion on Wittgenstein] |
| Full Idea: The 'self-evidence' of which Russell talks so much can only be dispensed with in logic if language itself prevents any logical mistake. | |
| From: comment on Ludwig Wittgenstein (Notebooks 1914-1916 [1915], 4) by Robin Jeshion - Frege's Notion of Self-Evidence 4 | |
| A reaction: Jeshion presents this as a key idea, turning against Frege, and is the real source of the 'linguistic turn' in philosophy. If self-evidence is abandoned, then language itself is the guide to truth, so study language. I think I prefer Frege. See Quine? |
| 18276 | A statement's logical form derives entirely from its constituents [Wittgenstein] |
| Full Idea: The logical form of the statement must already be given in the forms of its constituents. | |
| From: Ludwig Wittgenstein (Notebooks 1914-1916 [1915], 23e) | |
| A reaction: This would evidently require each constituent to have a 'logical form'. It is hard to see what that could beyond its part of speech. Do two common nouns have the same logical form? |
| 6563 | 'And' and 'not' are non-referring terms, which do not represent anything [Wittgenstein, by Fogelin] |
| Full Idea: Wittgenstein's 'fundamental idea' is that the 'and' and 'not' which guarantee the truth of "not p and not-p" are meaningful, but do not get their meaning by representing or standing for or referring to some kind of entity; they are non-referring terms. | |
| From: report of Ludwig Wittgenstein (Notebooks 1914-1916 [1915], §37) by Robert Fogelin - Walking the Tightrope of Reason Ch.1 | |
| A reaction: Wittgenstein then defines the terms using truth tables, to show what they do, rather than what they stand for. This seems to me to be a candidate for the single most important idea in the history of the philosophy of logic. |
| 23472 | The sense of propositions relies on the world's basic logical structure [Wittgenstein] |
| Full Idea: In order for a proposition to be CAPABLE of making sense, the world must already have the logical structure it has. The logic of the world is prior to all truth and falsehood. | |
| From: Ludwig Wittgenstein (Notebooks 1914-1916 [1915], p.14c) | |
| A reaction: It seems that in Tractatus it is propositions about facts which are true or false, but prior to the facts are substance and the objects, and it is there that we find the logical structure of the world. I see this view as modern stoicism. |
| 4885 | Identity is a very weak relation, which doesn't require interdefinability, or shared properties [Perry] |
| Full Idea: The truth of "a=b" doesn't require much of 'a' and 'b' other than that there is a single thing to which they both refer. They needn't be interdefinable, or have supervenient properties. In this sense, identity is a very weak relation. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §1.2) | |
| A reaction: Interesting. This is seeing the epistemological aspects of identity. Ontologically, identity must invoke Leibniz's Law, and is the ultimately powerful 'relation'. A given student, and the cause of a crop circle, may APPEAR to be quite different. |
| 4899 | Possible worlds thinking has clarified the logic of modality, but is problematic in epistemology [Perry] |
| Full Idea: Using possible worlds to model truth-conditions of statements has led to considerable clarity about the logic of modality. Attempts to use the system for epistemic purposes, however, have been plagued by problems. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §8.1) | |
| A reaction: Presumably what lurks behind this is a distinction between what is logically or naturally possible, and what appears to be possible from the perspective of a conscious mind. Is there a possible world in which I can fly? |
| 4898 | Possible worlds are indices for a language, or concrete realities, or abstract possibilities [Perry] |
| Full Idea: Possible worlds can be thought of as indices for models of the language in question, or as concrete realities (David Lewis), or as abstract ways the world might be (Robert Stalnaker), or in various other ways. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §8.1) | |
| A reaction: I strongly favour the Stalnaker route here. Reducing great metaphysics to mere language I find abhorrent, and I suspect that Lewis was trapped by his commitment to strong empiricism. We must embrace abstractions into our ontology. |
| 23500 | My main problem is the order of the world, and whether it is knowable a priori [Wittgenstein] |
| Full Idea: The great problem around which everything turns that I write is: is there an order in the world a priori, and if so what does it consist in? | |
| From: Ludwig Wittgenstein (Notebooks 1914-1916 [1915], 15.06.01) | |
| A reaction: Morris identifies this as a 'Kantian question'. I trace it back to stoicism. This question has never bothered me. It just seems weird to think that you can infer reality from the examination of your own thinking. Perhaps I should take it more seriously? |
| 2799 | Bayes' theorem explains why very surprising predictions have a higher value as evidence [Horwich] |
| Full Idea: Bayesianism can explain the fact that in science surprising predictions have greater evidential value, as the equation produces a higher degree of confirmation. | |
| From: Paul Horwich (Bayesianism [1992], p.42) |
| 2798 | Probability of H, given evidence E, is prob(H) x prob(E given H) / prob(E) [Horwich] |
| Full Idea: Bayesianism says ideally rational people should have degrees of belief (not all-or-nothing beliefs), corresponding with probability theory. Probability of H, given evidence E, is prob(H) X prob(E given H) / prob(E). | |
| From: Paul Horwich (Bayesianism [1992], p.41) |
| 4887 | We try to cause other things to occur by causing mental events to occur [Perry] |
| Full Idea: We try to cause other things to occur by causing mental events to occur. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §2.4) | |
| A reaction: A small and obvious, but important, point. Mental causation isn't just thoughts leading to physical happenings. Here Perry means that events can be designed to cause thoughts, such as a threatening letter. Not much room for epiphenomenalism here. |
| 4884 | Brain states must be in my head, and yet the pain seems to be in my hand [Perry] |
| Full Idea: The brain state will involve certain parts of the brain, whereas my feeling of pain seems to be located in my hand insofar as it has a bodily location. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §1.2) | |
| A reaction: This seems important to me. The brain is a ventriloquist. Perry implies that pain is quasi-disembodied, but it isn't, it is just experienced as IN the hand. Perhaps it is in the hand? Cutting the nerves loses contact with the pain. |
| 4888 | It seems plausible that many animals have experiences without knowing about them [Perry] |
| Full Idea: It seems quite plausible to me that many animals have experiences without knowing about them. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §3.1) | |
| A reaction: I agree, which makes us acknowledge levels of consciousness, which probably applies to human experience as well. The simplest idea is to distinguish between experiences which involve concepts, and those which don't. Animals sometimes appear surprised. |
| 22323 | The philosophical I is the metaphysical subject, the limit - not a part of the world [Wittgenstein] |
| Full Idea: The philosophical I is not the man, not the human body, or the human soul of wh9ch psychology treats, but the metaphysical subject, the limit - not a part of the world. | |
| From: Ludwig Wittgenstein (Notebooks 1914-1916 [1915], 1916. 2 Sep), quoted by Michael Potter - The Rise of Analytic Philosophy 1879-1930 58 Intro | |
| A reaction: This is to treat the self as a phenomenon of thought, rather than of a human being. So if a machine could think, would it hence necessarily have a metaphysical self? |
| 4891 | If epiphenomenalism just says mental events are effects but not causes, it is consistent with physicalism [Perry] |
| Full Idea: Epiphenomenalism is usually considered to be a form of dualism, but if we define it as the doctrine that conscious events are effects but not causes, it appears to be consistent with physicalism. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §4.2) | |
| A reaction: Interesting. The theory was invented to put mind outside physics, and make the closure of physics possible. However, being capable of causing things seems to be a necessary condition for physical objects. An effect in one domain is a cause in another. |
| 4900 | Prior to Kripke, the mind-brain identity theory usually claimed that the identity was contingent [Perry] |
| Full Idea: Advocates of the mind-body identity theory typically claimed that identity between particular mental states and brain states was contingent, until Kripke argued persuasively that identity is always necessary. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §8.1) | |
| A reaction: Kripke wanted to argue against the identity theory, but what he seems to have done is reformulate it into a much more powerful version (involving necessary identity). |
| 4892 | If physicalists stick with identity (not supervenience), Martian pain will not be like ours [Perry] |
| Full Idea: The physicalist should not retreat to causal supervenience but should stick with identity. This means we will have to accept that a Martian and I (when in pain) are not in the same phenomenal state. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §4.3) | |
| A reaction: We naturally presume that frogs feel pain as we do, but many different phenomenal states could lead to the same behavioural end. Only an unpleasant feeling is required. A foul smell would do. Frogs could function with inverted qualia, too. |
| 4889 | Although we may classify ideas by content, we individuate them differently, as their content can change [Perry] |
| Full Idea: Although we classify ideas by content for many purposes, we do not individuate them by content. The content of an idea can change. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §3.2) | |
| A reaction: As the compiler of this database, I find this very appealing. The mind works exactly like a database. I have a 'file' (Perry's word) marked "London", the content of which undergoes continual change. I am a database management system. |
| 4896 | The intension of an expression is a function from possible worlds to an appropriate extension [Perry] |
| Full Idea: In possible-worlds semantics, expressions have intensions, which are functions from possible worlds to appropriate extensions (names to individuals, n-place predicates to n-tuples, and sentences to truth values, built from parts). | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §8.1) | |
| A reaction: Interesting. Perry distinguishes 'referential' (or 'subject matter') content, which is prior to the link to extensions - a link which creates 'reflexive' content. He is keen that they should not become confused. True knowledge is 'situated'. |
| 23481 | Propositions assemble a world experimentally, like the model of a road accident [Wittgenstein] |
| Full Idea: In the proposition a world is as it were put together experimentally. (As when in the law court in Paris a motor-car accident is represented by means of dolls, etc). | |
| From: Ludwig Wittgenstein (Notebooks 1914-1916 [1915], 14.09.29) | |
| A reaction: [see Tractatus 4.031] This is the first appearance of LW's picture (or model) theory of meaning. It may well be the best theory of meaning anyone has come up with, since meaning being out in the world strikes me as absurd. |
| 4897 | A proposition is a set of possible worlds for which its intension delivers truth [Perry] |
| Full Idea: The proposition expressed by a sentence can be thought of as a set of possible worlds, the worlds for which its intension delivers truth. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §8.1) | |
| A reaction: It has always struck me as important to hang on to the concept of a 'proposition' (over and above sentences). This idea gives a metaphysics for the concept, and the 'language of thought' offers appropriate brain structures. A neat picture. |
| 4890 | A sharp analytic/synthetic line can rarely be drawn, but some concepts are central to thought [Perry] |
| Full Idea: Although there is seldom a sharp analytic/synthetic distinction to be drawn in the case of our concepts, there are clearly things that are more and less central. | |
| From: John Perry (Knowledge, Possibility and Consciousness [2001], §3.2) | |
| A reaction: Most Americans seem enslaved to Quine on this one, so it is nice to see the obvious being stated for once. Human thought is an organic offshoot of the natural world. To think it is all arbitrary and changeable is human arrogance. |
| 4678 | Absolute prohibitions are the essence of ethics, and suicide is the most obvious example [Wittgenstein] |
| Full Idea: If suicide is allowed, then everything is allowed. If anything is not allowed, then suicide is not allowed. This throws a light on the nature of ethics, for suicide is, so to speak, the elementary sin. | |
| From: Ludwig Wittgenstein (Notebooks 1914-1916 [1915], end), quoted by Jonathan Glover - Causing Death and Saving Lives §13 | |
| A reaction: This reveals the religious streak in Wittgenstein. I am reluctant to judge suicide, but this seems wrong. Should a 'jumper' worry if they land on someone else and kill them? Of course they should. |