21 ideas
| 13838 | A decent modern definition should always imply a semantics [Hacking] |
| Full Idea: Today we expect that anything worth calling a definition should imply a semantics. | |
| From: Ian Hacking (What is Logic? [1979], §10) | |
| A reaction: He compares this with Gentzen 1935, who was attempting purely syntactic definitions of the logical connectives. |
| 13833 | 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking] |
| Full Idea: 'Dilution' (or 'Thinning') provides an essential contrast between deductive and inductive reasoning; for the introduction of new premises may spoil an inductive inference. | |
| From: Ian Hacking (What is Logic? [1979], §06.2) | |
| A reaction: That is, inductive logic (if there is such a thing) is clearly non-monotonic, whereas classical inductive logic is monotonic. |
| 13834 | Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking] |
| Full Idea: If A |- B and B |- C, then A |- C. This generalises to: If Γ|-A,Θ and Γ,A |- Θ, then Γ |- Θ. Gentzen called this 'cut'. It is the transitivity of a deduction. | |
| From: Ian Hacking (What is Logic? [1979], §06.3) | |
| A reaction: I read the generalisation as 'If A can be either a premise or a conclusion, you can bypass it'. The first version is just transitivity (which by-passes the middle step). |
| 13835 | Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking] |
| Full Idea: Only the cut rule can have a conclusion that is less complex than its premises. Hence when cut is not used, a derivation is quite literally constructive, building up from components. Any theorem obtained by cut can be obtained without it. | |
| From: Ian Hacking (What is Logic? [1979], §08) |
| 13845 | The various logics are abstractions made from terms like 'if...then' in English [Hacking] |
| Full Idea: I don't believe English is by nature classical or intuitionistic etc. These are abstractions made by logicians. Logicians attend to numerous different objects that might be served by 'If...then', like material conditional, strict or relevant implication. | |
| From: Ian Hacking (What is Logic? [1979], §15) | |
| A reaction: The idea that they are 'abstractions' is close to my heart. Abstractions from what? Surely 'if...then' has a standard character when employed in normal conversation? |
| 13840 | First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking] |
| Full Idea: First-order logic is the strongest complete compact theory with a Löwenheim-Skolem theorem. | |
| From: Ian Hacking (What is Logic? [1979], §13) |
| 13844 | A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking] |
| Full Idea: Henkin proved that there is no first-order treatment of branching quantifiers, which do not seem to involve any idea that is fundamentally different from ordinary quantification. | |
| From: Ian Hacking (What is Logic? [1979], §13) | |
| A reaction: See Hacking for an example of branching quantifiers. Hacking is impressed by this as a real limitation of the first-order logic which he generally favours. |
| 13842 | Second-order completeness seems to need intensional entities and possible worlds [Hacking] |
| Full Idea: Second-order logic has no chance of a completeness theorem unless one ventures into intensional entities and possible worlds. | |
| From: Ian Hacking (What is Logic? [1979], §13) |
| 13837 | With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking] |
| Full Idea: My doctrine is that the peculiarity of the logical constants resides precisely in that given a certain pure notion of truth and consequence, all the desirable semantic properties of the constants are determined by their syntactic properties. | |
| From: Ian Hacking (What is Logic? [1979], §09) | |
| A reaction: He opposes this to Peacocke 1976, who claims that the logical connectives are essentially semantic in character, concerned with the preservation of truth. |
| 13839 | Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking] |
| Full Idea: For some purposes the variables of first-order logic can be regarded as prepositions and place-holders that could in principle be dispensed with, say by a system of arrows indicating what places fall in the scope of which quantifier. | |
| From: Ian Hacking (What is Logic? [1979], §11) | |
| A reaction: I tend to think of variables as either pronouns, or as definite descriptions, or as temporary names, but not as prepositions. Must address this new idea... |
| 13843 | If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking] |
| Full Idea: A Löwenheim-Skolem theorem holds for anything which, on my delineation, is a logic. | |
| From: Ian Hacking (What is Logic? [1979], §13) | |
| A reaction: I take this to be an unusually conservative view. Shapiro is the chap who can give you an alternative view of these things, or Boolos. |
| 23513 | Single neurons can carry out complex functions [Seth] |
| Full Idea: It is increasingly apparent that even single neurons are capable of carrying out highly complex functions all by themselves. | |
| From: Anil Seth (Being You [2021], I.1 n) | |
| A reaction: Bang goes the simple connectionist account of consciousness. |
| 23514 | The cerbellum has a huge number of neurons, but little involvement in consciousness [Seth] |
| Full Idea: The cerebellum [at the back] has about four times as many neurons as the rest of the brain put together, but seems barely involved in consciousness. | |
| From: Anil Seth (Being You [2021], I.2) | |
| A reaction: I wonder if it also has four times as many connections? |
| 23516 | Maybe a system is conscious if the whole generates more information than its parts [Seth] |
| Full Idea: The main claim of Tononi's 'integrated information theory' is that a system is conscious to the extent that its whole generates more information than its parts. | |
| From: Anil Seth (Being You [2021], I.3) | |
| A reaction: Seth seems to present this as an 'interesting' proposal. I find it unlikely that consciousness could be explain in terms of information, or that a machine constructed on this principle would thus become conscious. (Databases pass this test). |
| 23519 | The self is embodied, perspectival, volitional, narrative and social [Seth, by PG] |
| Full Idea: The elements of a self are 1) embodied - related directly to the body, 2) perspectival - having a viewpoint, 3) volitional - being an agent, 4) narrative - aware of past and future, and 5) social - as others perceive me. | |
| From: report of Anil Seth (Being You [2021], III.8) by PG - Db (ideas) | |
| A reaction: [summarised] Seth says there are distinctive emotions associated with each of these aspects of the self. This list is very helpful, as a discouragement for anyone who wants to pick one of these as the sole true nature of the self. |
| 23518 | Modern AI is mostly machine-based pattern recognition [Seth] |
| Full Idea: Much of today's AI is best described as sophisticated machine-based pattern recognition. | |
| From: Anil Seth (Being You [2021], IV.13) | |
| A reaction: Personally I wouldn't want to underestimate the extent to which human intelligence is also pattern recognition (across time as well as in space). |
| 23517 | Volition is felt as doing what you want, with possible alternatives, and a source from within [Seth] |
| Full Idea: The experience of volition is defined by 1) the feeling that I am doing what I want to do, 2) that I could have done otherwise, and 3) that voluntary actions seem to come from within. | |
| From: Anil Seth (Being You [2021], III.11) | |
| A reaction: Note that these can all be cited without reference to their feeling 'free'. |
| 20420 | The emotion expressed is non-conscious, but feels oppressive until expression relieves it [Collingwood] |
| Full Idea: The emotion expressed is one of whose nature the person feeling it is no longer conscious. As unexpressed, he feels it in a helpless and oppressed way; as expressed, the oppression has vanished. His mind is somehow lightened and eased. | |
| From: R.G. Collingwood (The Principles of Art [1938], p.110), quoted by Gary Kemp - Croce and Collingwood 1 | |
| A reaction: It sounds like the regular smoking of cigarettes. This is Collingwood answer the doubts I felt about Idea 20419. I would have thought the desire of Picasso was to create another painting, but not to express yet another new oppressive feeling. |
| 20421 | Art exists ideally, purely as experiences in the mind of the perceiver [Collingwood, by Kemp] |
| Full Idea: For Collingwood (and Croce) the work of art is an ideal object; …they are things that exist only in the mind, that is, only when one perceives. …The physical work exists to make this experience available. | |
| From: report of R.G. Collingwood (The Principles of Art [1938]) by Gary Kemp - Croce and Collingwood 2 | |
| A reaction: This means that the paintings in a gallery cease to be works of art when the gallery is shut, which sounds odd. I suppose 'work of art' is ambiguous, between the experience (right) and the facilitator of the experience (wrong). |
| 20406 | Art clarifies the artist's mind and feelings, thus leading to self-knowledge [Collingwood, by Davies,S] |
| Full Idea: Collingwood suggests art should be thought of not as product or artifact but as an act or process of expression through which the artist clarifies her initially vague emotions and states of mind. As such, it is a source of self-knowledge. | |
| From: report of R.G. Collingwood (The Principles of Art [1938], Ch.6) by Stephen Davies - The Philosophy of Art (2nd ed) 8.4 | |
| A reaction: I might believe this of writing novels, but not much else. |
| 23515 | Human exceptionalism plagues biology, and most other human thinking [Seth] |
| Full Idea: Human exceptionalism has repeatedly plagued biology, and has darkened the history of human thought everywhere. | |
| From: Anil Seth (Being You [2021], I.2) | |
| A reaction: I increasingly agree with this, as much in philosophy as in biology. We really need to get used to our place in evolution. |