49 ideas
3600 | Slow and accurate thought makes the greatest progress [Descartes] |
Full Idea: Those who go forward only very slowly can progress much further if they always keep to the right path, than those who run and wander off it. | |
From: René Descartes (A Discourse on Method [1637], §1.2) | |
A reaction: Like Descartes' 'Method'. This seems to place a low value on 'nous' or intuition. |
3601 | Most things in human life seem vain and useless [Descartes] |
Full Idea: Looking at the various activities and enterprises of mankind with the eye of a philosopher, there is hardly one which does not seem to me vain and useless. | |
From: René Descartes (A Discourse on Method [1637], §1.3) | |
A reaction: Well, yes. The obvious retort is that everything is vain and useless; or if not, then certainly metaphysics is. Useful for what? Is ornamental gardening useless, or sport? Art? What is the use of cosmology? He's right, of course. |
3602 | Almost every daft idea has been expressed by some philosopher [Descartes] |
Full Idea: There is nothing one can imagine so strange or so unbelievable that has not been said by one or other of the philosophers. | |
From: René Descartes (A Discourse on Method [1637], §2.16) | |
A reaction: Actually I think that extensive areas of logical possibilities for existence remain totally unexplored. On the other hand, most of the metaphysical beliefs of most of the human race, including the majority of philosophers, strike me as being false. |
3603 | Methodical thinking is cautious, analytical, systematic, and panoramic [Descartes, by PG] |
Full Idea: Descartes' four principles for his method of thinking are: be cautious, analyse the problem, be systematic from simple to complex, and keep an overview of the problem | |
From: report of René Descartes (A Discourse on Method [1637], §2.18) by PG - Db (ideas) |
3612 | Clear and distinct conceptions are true because a perfect God exists [Descartes] |
Full Idea: That the things we grasp very clearly and very distinctly are all true, is assured only because God is or exists, and because he is a perfect Being. | |
From: René Descartes (A Discourse on Method [1637], §4.38) |
3610 | Truth is clear and distinct conception - of which it is hard to be sure [Descartes] |
Full Idea: I take it as a general rule that the things we conceive very clearly and very distinctly are all true, but that there is merely some difficulty in properly discerning which are those which we distinctly conceive. | |
From: René Descartes (A Discourse on Method [1637], §4.33) |
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. |
18806 | Frege thought traditional categories had psychological and linguistic impurities [Frege, by Rumfitt] |
Full Idea: Frege rejected the traditional categories as importing psychological and linguistic impurities into logic. | |
From: report of Gottlob Frege (Function and Concept [1891]) by Ian Rumfitt - The Boundary Stones of Thought 1.2 | |
A reaction: Resisting such impurities is the main motivation for making logic entirely symbolic, but it doesn't follow that the traditional categories have to be dropped. |
8490 | First-level functions have objects as arguments; second-level functions take functions as arguments [Frege] |
Full Idea: Just as functions are fundamentally different from objects, so also functions whose arguments are and must be functions are fundamentally different from functions whose arguments are objects. The latter are first-level, the former second-level, functions. | |
From: Gottlob Frege (Function and Concept [1891], p.38) | |
A reaction: In 1884 he called it 'second-order'. This is the standard distinction between first- and second-order logic. The first quantifies over objects, the second over intensional entities such as properties and propositions. |
8492 | Relations are functions with two arguments [Frege] |
Full Idea: Functions of one argument are concepts; functions of two arguments are relations. | |
From: Gottlob Frege (Function and Concept [1891], p.39) | |
A reaction: Nowadays we would say 'two or more'. Another interesting move in the aim of analytic philosophy to reduce the puzzling features of the world to mathematical logic. There is, of course, rather more to some relations than being two-argument functions. |
8487 | Arithmetic is a development of logic, so arithmetical symbolism must expand into logical symbolism [Frege] |
Full Idea: I am of the opinion that arithmetic is a further development of logic, which leads to the requirement that the symbolic language of arithmetic must be expanded into a logical symbolism. | |
From: Gottlob Frege (Function and Concept [1891], p.30) | |
A reaction: This may the the one key idea at the heart of modern analytic philosophy (even though logicism may be a total mistake!). Logic and arithmetical foundations become the master of ontology, instead of the servant. The jury is out on the whole enterprise. |
18899 | Frege takes the existence of horses to be part of their concept [Frege, by Sommers] |
Full Idea: Frege regarded the existence of horses as a property of the concept 'horse'. | |
From: report of Gottlob Frege (Function and Concept [1891]) by Fred Sommers - Intellectual Autobiography 'Realism' |
4028 | Frege allows either too few properties (as extensions) or too many (as predicates) [Mellor/Oliver on Frege] |
Full Idea: Frege's theory of properties (which he calls 'concepts') yields too few properties, by identifying coextensive properties, and also too many, by letting every predicate express a property. | |
From: comment on Gottlob Frege (Function and Concept [1891]) by DH Mellor / A Oliver - Introduction to 'Properties' §2 | |
A reaction: Seems right; one extension may have two properties (have heart/kidneys), two predicates might express the same property. 'Cutting nature at the joints' covers properties as well as objects. |
8489 | The concept 'object' is too simple for analysis; unlike a function, it is an expression with no empty place [Frege] |
Full Idea: I regard a regular definition of 'object' as impossible, since it is too simple to admit of logical analysis. Briefly: an object is anything that is not a function, so that an expression for it does not contain any empty place. | |
From: Gottlob Frege (Function and Concept [1891], p.32) | |
A reaction: Here is the core of the programme for deriving our ontology from our logic and language, followed through by Russell and Quine. Once we extend objects beyond the physical, it becomes incredibly hard to individuate them. |
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. |
3605 | We can believe a thing without knowing we believe it [Descartes] |
Full Idea: The action of thought by which one believes a thing, being different from that by which one knows that one believes it, they often exist the one without the other. | |
From: René Descartes (A Discourse on Method [1637], §3.23) |
1583 | In morals Descartes accepts the conventional, but rejects it in epistemology [Roochnik on Descartes] |
Full Idea: Descartes' procedure for treating values (accepting normal conventions when faced with uncertainty) is the exact antithesis of that used to attain knowledge. | |
From: comment on René Descartes (A Discourse on Method [1637], §3.23) by David Roochnik - The Tragedy of Reason p.73 |
3607 | In thinking everything else false, my own existence remains totally certain [Descartes] |
Full Idea: While I decided to think that everything was false, it followed necessarily that I who thought thus must be something; the truth 'I think therefore I am' was so certain that the most extravagant scepticism could never shake it. | |
From: René Descartes (A Discourse on Method [1637], §4.32) |
3617 | I aim to find the principles and causes of everything, using the seeds within my mind [Descartes] |
Full Idea: I have tried to find in general the principles or first causes of everything which is or which may be in the world, ..without taking them from any other source than from certain seeds of truth which are naturally in our minds. | |
From: René Descartes (A Discourse on Method [1637], §6.64) |
3611 | Understanding, rather than imagination or senses, gives knowledge [Descartes] |
Full Idea: Neither our imagination nor our senses could ever assure us of anything, if our understanding did not intervene. | |
From: René Descartes (A Discourse on Method [1637], §4.37) |
3606 | I was searching for reliable rock under the shifting sand [Descartes] |
Full Idea: My whole plan had for its aim simply to give me assurance, and the rejection of shifting ground and sand in order to find rock or clay. | |
From: René Descartes (A Discourse on Method [1637], §3.29) | |
A reaction: I take this to be characteristic of an age when religion is being quietly rocked by the revival of ancient scepticism. If he'd settled for fallibilism, our civilization would have gone differently. |
3604 | When rebuilding a house, one needs alternative lodgings [Descartes] |
Full Idea: Before beginning to rebuild the house in which one lives…. one must also provide oneself with some other accommodation in which to be lodge conveniently while the work is going on. | |
From: René Descartes (A Discourse on Method [1637], §3.22) |
3618 | Only experiments can settle disagreements between rival explanations [Descartes] |
Full Idea: I observe almost no individual effect without immediately knowing that it can be deduced in many different ways, ..and I know of no way to resolve this but by experiments such that the results are different according to different explanations. | |
From: René Descartes (A Discourse on Method [1637], §6.65) |
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. |
3615 | Little reason is needed to speak, so animals have no reason at all [Descartes] |
Full Idea: Animals not only have less reason than men, but they have none at all; for we see that very little of it is required in order to be able to speak. | |
From: René Descartes (A Discourse on Method [1637], §5.58) |
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. |
3609 | I am a thinking substance, which doesn't need a place or material support [Descartes] |
Full Idea: I concluded that I was a substance, of which the whole essence or nature consists in thinking, and which, in order to exist, needs no place and depends on no material thing. | |
From: René Descartes (A Discourse on Method [1637], §4.33) | |
A reaction: To me that sounds like "I concluded that I wasn't a human being", which highlights the bizarre wishful thinking that seems to have gripped the human race for the first few thousand years of its serious thinking. |
3608 | I can deny my body and the world, but not my own existence [Descartes] |
Full Idea: I could pretend that I had no body, and that there was no world or place that I was in, but I could not, for all that, pretend that I did not exist. | |
From: René Descartes (A Discourse on Method [1637], §4.32) | |
A reaction: He makes the (in my opinion) appalling blunder of thinking that because he can pretend that he has no body, that therefore he might not have one. I can pretend that gold is an unusual form of cheese. However, "I don't exist" certainly sounds wrong. |
3613 | Reason is universal in its responses, but a physical machine is constrained by its organs [Descartes] |
Full Idea: Whereas reason is a universal instrument which can serve on any kind of occasion, the organs of a machine need a disposition for each action; so it is impossible to have enough different organs in a machine to respond to all the occurrences of life. | |
From: René Descartes (A Discourse on Method [1637], §5.57) | |
A reaction: How can Descartes know that reason is 'universal' rather than just 'very extensive'? Is there any information which cannot be encoded in a computer? It doesn't feel as if there any intrinsic restrictions to reason, but note Idea 4688. |
3616 | The soul must unite with the body to have appetites and sensations [Descartes] |
Full Idea: It is not sufficient that the reasonable soul should be lodged in the body like a pilot in a ship, unless perhaps to move its limbs, but it needs to be united more closely with the body in order to have sensations and appetites, and so be a true man. | |
From: René Descartes (A Discourse on Method [1637], §5.59) | |
A reaction: The idea that the pineal gland is the link suggests that Descartes has the 'pilot' view, but this idea shows that he believes in very close and complex interaction between mind and body. But how can a mind 'have' appetites if it has no physical needs? |
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. |
3614 | A machine could speak in response to physical stimulus, but not hold a conversation [Descartes] |
Full Idea: One may conceive of a machine made so as to emit words, and even emit them in response to a change in its bodily organs, such as being touched, but not to reply to the sense of everything said in its presence, as the most unintelligent men can. | |
From: René Descartes (A Discourse on Method [1637], §5.56) | |
A reaction: A critique of the Turing Test, written in 1637! You have to admire. Because of the advent of the microprocessor, we can 'conceive' more sophisticated, multi-level machines than Descartes could come up with. |
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'. |
9947 | Concepts are the ontological counterparts of predicative expressions [Frege, by George/Velleman] |
Full Idea: Concepts, for Frege, are the ontological counterparts of predicative expressions. | |
From: report of Gottlob Frege (Function and Concept [1891]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.2 | |
A reaction: That sounds awfully like what many philosophers call 'universals'. Frege, as a platonist (at least about numbers), I would take to be in sympathy with that. At least we can say that concepts seem to be properties. |
10319 | An assertion about the concept 'horse' must indirectly speak of an object [Frege, by Hale] |
Full Idea: Frege had a notorious difficulty over the concept 'horse', when he suggests that if we wish to assert something about a concept, we are obliged to proceed indirectly by speaking of an object that represents it. | |
From: report of Gottlob Frege (Function and Concept [1891], Ch.2.II) by Bob Hale - Abstract Objects | |
A reaction: This sounds like the thin end of a wedge. The great champion of objects is forced to accept them here as a façon de parler, when elsewhere they have ontological status. |
8488 | A concept is a function whose value is always a truth-value [Frege] |
Full Idea: A concept in logic is closely connected with what we call a function. Indeed, we may say at once: a concept is a function whose value is always a truth-value. ..I give the name 'function' to what is meant by the 'unsaturated' part. | |
From: Gottlob Frege (Function and Concept [1891], p.30) | |
A reaction: So a function becomes a concept when the variable takes a value. Problems arise when the value is vague, or the truth-value is indeterminable. |
9948 | Unlike objects, concepts are inherently incomplete [Frege, by George/Velleman] |
Full Idea: For Frege, concepts differ from objects in being inherently incomplete in nature. | |
From: report of Gottlob Frege (Function and Concept [1891]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.2 | |
A reaction: This is because they are 'unsaturated', needing a quantified variable to complete the sentence. This could be a pointer towards Quine's view of properties, as simply an intrinsic feature of predication about objects, with no separate identity. |
4972 | I may regard a thought about Phosphorus as true, and the same thought about Hesperus as false [Frege] |
Full Idea: From sameness of meaning there does not follow sameness of thought expressed. A fact about the Morning Star may express something different from a fact about the Evening Star, as someone may regard one as true and the other false. | |
From: Gottlob Frege (Function and Concept [1891], p.14) | |
A reaction: This all gets clearer if we distinguish internalist and externalist theories of content. Why take sides on this? Why not just ask 'what is in the speaker's head?', 'what does the sentence mean in the community?', and 'what is the corresponding situation?' |
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. |
1581 | Greeks elevate virtues enormously, but never explain them [Descartes] |
Full Idea: The ancient pagans place virtues on a high plateau and make them appear the most valuable thing in the world, but they do not sufficiently instruct us about how to know them. | |
From: René Descartes (A Discourse on Method [1637], §1.8) |
16686 | God has established laws throughout nature, and implanted ideas of them within us [Descartes] |
Full Idea: I have noticed certain laws that God has so established in nature, and of which he has implanted such notions in our souls, that …we cannot doubt that they are exactly observed in everything that exists or occurs in the world. | |
From: René Descartes (A Discourse on Method [1637], pt 5), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 15.5 | |
A reaction: This is the view of laws which still seems to be with us (and needs extirpating) - that some outside agency imposes them on nature. I suspect that even Richard Feynman thought of laws like that, because he despised philosophy, and was thus naïve. |
8491 | The Ontological Argument fallaciously treats existence as a first-level concept [Frege] |
Full Idea: The ontological proof of God's existence suffers from the fallacy of treating existence as a first-level concept. | |
From: Gottlob Frege (Function and Concept [1891], p.38 n) | |
A reaction: [See Idea 8490 for first- and second-order functions] This is usually summarised as the idea that existence is a quantifier rather than a predicate. |