25 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. |
| 5791 | Reduction is either by elimination, or by explanation [Searle] |
| Full Idea: One sense of 'reduction' is eliminative, in getting rid of a phenomenon by showing that it is really something else (as the earth's rotation eliminates 'sunsets'), but another sense does not get rid of it (as in the explanation of solidity by molecules). | |
| From: John Searle (The Mystery of Consciousness [1997], Ch.2) | |
| A reaction: These are bad analogies. You can't 'eliminate' a sunset - you just accept that the event is relative to a viewpoint. If we are discussing ontology, we will not admit the existence of sunsets, but we won't have an ontological category of 'solidity' either. |
| 5799 | Eliminative reduction needs a gap between appearance and reality, as in sunsets [Searle] |
| Full Idea: Eliminative reductions require a distinction between reality and appearance; for example, the sun appears to set but the reality is that the earth rotates. | |
| From: John Searle (The Mystery of Consciousness [1997], Concl 2.10) | |
| A reaction: A bad analogy. You don't 'eliminate' sunsets. It is just 'Galilean' relativity - you thought it was your train moving, then you discover it was the other one. You don't eliminate hallucinations when you show that they don't correspond to reality. |
| 5790 | A property is 'emergent' if it is caused by elements of a system, when the elements lack the property [Searle] |
| Full Idea: An emergent property of a system is causally explained by elements of the system, but it is not a property of the elements, and cannot be explained by a summation of their properties. The behaviour of H2O explains liquidity, but molecules aren't liquid. | |
| From: John Searle (The Mystery of Consciousness [1997], Ch.1) | |
| A reaction: The genie is 'emergent' from the lamp, and so (in Searle's meaning) is the lamp's solidity. I agree that the mind is 'emergent' in Searle's very weak sense, if that only means that one neuron can't be conscious, but lots together can. |
| 16668 | Modes of things exist in some way, without being full-blown substances [Gassendi] |
| Full Idea: Modes are not nothing but something more than mere nothing; they are therefore 'res' of some kind, not substantial of course, but at least modal. | |
| From: Pierre Gassendi (Disquisitions [1644], II.3.4), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 260 | |
| A reaction: This is the great modern atomist talking pure scholastic metaphysics. He's been reading Suárez. Gassendi seems to accept more than one type of existence. |
| 5792 | Explanation of how we unify our mental stimuli into a single experience is the 'binding problem' [Searle] |
| Full Idea: The 'binding problem' is how to explain how the brain binds all our different stimuli into a single unified experience of an object. | |
| From: John Searle (The Mystery of Consciousness [1997], Ch.2) | |
| A reaction: This may be the best way of expressing what philosophers call (after Chalmers) the 'Hard Question'. Large objects are held together by gravity, and small objects by electro-magnetism. We don't see a 'binding problem' in the function of a leaf. |
| 5786 | A system is either conscious or it isn't, though the intensity varies a lot [Searle] |
| Full Idea: A system is either conscious or it isn't, but within the field of consciousness there are states of intensity ranging from drowsiness to full awareness. | |
| From: John Searle (The Mystery of Consciousness [1997], Ch.1) | |
| A reaction: I think this all-or-nothing view is the last vestiges of Cartesian dualism, and is quite wrong. Heaps of neuroscience (about blindsight, subliminal awareness, neurosis etc.) says we will never understand the mind if we think it is only the conscious part. |
| 5794 | Consciousness has a first-person ontology, which only exists from a subjective viewpoint [Searle] |
| Full Idea: Consciousness has a first-person or subjective ontology, by which I mean that conscious states only exist when experienced by a subject and they exist only from the first-person point of view of that subject. | |
| From: John Searle (The Mystery of Consciousness [1997], Ch.5 App) | |
| A reaction: I think this is nonsense, and I don't think Searle believes it. He ruthlessly attacks so-called 'eliminativists', but the definition he gives here would make him an eliminativist about other minds. There is no such thing as 'first-person' ontology. |
| 5795 | There isn't one consciousness (information-processing) which can be investigated, and another (phenomenal) which can't [Searle] |
| Full Idea: There are not two kinds of consciousness, an information-processing consciousness that is amenable to scientific investigation and a phenomenal, what-it-subjectively-feels-like form of consciousness that will forever remain mysterious. | |
| From: John Searle (The Mystery of Consciousness [1997], Concl.1) | |
| A reaction: Fodor appears to be the main target of this remark. The view that we can explain intentionality but not qualia is currently very fashionable. I am sympathetic to Searle here. Consciousness isn't an epiphenomenon, it is essential to all thought. |
| 5788 | The use of 'qualia' seems to imply that consciousness and qualia are separate [Searle] |
| Full Idea: I am hesitant to use the word 'quale/qualia', because it gives the impression that there are two separate phenomena, consciousness and qualia. | |
| From: John Searle (The Mystery of Consciousness [1997], Ch.1) | |
| A reaction: He is trying to resist going back to 'sense-data', sitting uneasily between reality and our experience of it. Personally I am quite happy with qualia as an aspect of consciousness - just as I am happy with consciousness as an 'aspect' of brain. |
| 5789 | I now think syntax is not in the physics, but in the eye of the beholder [Searle] |
| Full Idea: It seems to me now that syntax is not intrinsic to the physics of the system, but is in the eye of the beholder. | |
| From: John Searle (The Mystery of Consciousness [1997], Ch.1) | |
| A reaction: This seems right, in that whether strung beads are a toy or an abacus depends on the user. It doesn't follow that the 'beholder' stands outside the physics. A beholder is another physical system, of a particular type of high complexity. |
| 5798 | Consciousness has a first-person ontology, so it cannot be reduced without omitting something [Searle] |
| Full Idea: Consciousness has a first-person or subjective ontology and so cannot be reduced to anything that has third-person or objective ontology. If you try to reduce or eliminate one in favour of the other you leave something out. | |
| From: John Searle (The Mystery of Consciousness [1997], Concl 2.10) | |
| A reaction: Misconceived. There is no such thing as 'first-person' ontology, though there are subjective viewpoints, but then a camera has a viewpoint which is lost if you eliminate it. If consciousness is physical events, that leaves viewpoints untouched. |
| 5787 | There is non-event causation between mind and brain, as between a table and its solidity [Searle] |
| Full Idea: The solidity of a table is explained causally by the behaviour of the molecules of which it is composed, but the solidity is not an extra event, it is just a feature of the table. This non-event causation models the relationship of mind and brain. | |
| From: John Searle (The Mystery of Consciousness [1997], Ch.1) | |
| A reaction: He calls it 'non-event' causation, while referring to the 'behaviour of molecules'. Ask a physicist what a 'feature' is. Better to think of it as one process 'emerging' as another process at the macro-level. |
| 5797 | The pattern of molecules in the sea is much more complex than the complexity of brain neurons [Searle] |
| Full Idea: The pattern of molecules in the ocean is vastly more complex than any pattern of neurons in my brain. | |
| From: John Searle (The Mystery of Consciousness [1997], Concl 2.6) | |
| A reaction: A nice warning for anyone foolish enough to pin their explanatory hopes simply on 'complexity', but we would not be so foolish. A subtler account of complexity (e.g. by Edelman and Tononi) might make brains much more complex than oceans. |
| 5796 | If tree rings contain information about age, then age contains information about rings [Searle] |
| Full Idea: You could say that tree-rings contain information about the age of a tree, but you could as well say that the age of a tree in years contains information about the number of rings in a tree stump. ..'Information' is not a real causal feature of the world. | |
| From: John Searle (The Mystery of Consciousness [1997], Concl 2.5) | |
| A reaction: A nice point for fans of 'information' to ponder. However, you cannot deny the causal connection between the age and the rings. Information has a subjective aspect, but you cannot, for example, eliminate the role of DNA in making organisms. |