23 ideas
| 15545 | Armstrong's analysis seeks truthmakers rather than definitions [Lewis] |
| Full Idea: I suggest that Armstrong has an unfamiliar notion of analysis, as not primarily a quest for definitions, but as a quest for truth-makers. | |
| From: David Lewis (Armstrong on combinatorial possibility [1992], 'The demand') | |
| A reaction: This is not a dichotomy, I think, but a shift of emphasis. A definition will probably refer to truthmakers; a decent account of truthmakers would approximate a definition. |
| 15546 | Predications aren't true because of what exists, but of how it exists [Lewis] |
| Full Idea: Predications seem, for the most part, to be true not because of whether things are, but because of how things are. | |
| From: David Lewis (Armstrong on combinatorial possibility [1992], 'The demand') | |
| A reaction: This simple point shows that you get into a tangle if you insist that truthmakers just consist of what exists. Lewis says Armstrong offers states of affairs as truthmakers for predications. |
| 15548 | Say 'truth is supervenient on being', but construe 'being' broadly [Lewis] |
| Full Idea: I want to say that 'truth is supervenient on being', but as an Ostrich about universals I want to construe 'being' broadly. | |
| From: David Lewis (Armstrong on combinatorial possibility [1992], 'Truth') | |
| A reaction: [His slogan is borrowed from Bigelow 1988:132-,158-9] This seems much more promising that the more precise and restricted notion of truthmakers, as resting on the existence of particular things. Presentism is the big test case. |
| 14399 | Presentism says only the present exists, so there is nothing for tensed truths to supervene on [Lewis] |
| Full Idea: Presentism says that although there is nothing outside the present, yet there are past-tensed and future-tensed truths that do not supervene on the present, and hence do not supervene on being. | |
| From: David Lewis (Armstrong on combinatorial possibility [1992], p.207) | |
| A reaction: Since I rather like both presentism and truth supervening on being, this observation comes as rather a devastating blow. I thought philosophy would be quite easy, but it's turning out to be rather tricky. Could tensed truths supervene on the present? |
| 11211 | If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt] |
| Full Idea: If a designated conclusion follows from the premisses, but the argument involves two howlers which cancel each other out, then the moral is that the path an argument takes from premisses to conclusion does matter to its logical evaluation. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], II) | |
| A reaction: The drift of this is that our view of logic should be a little closer to the reasoning of ordinary language, and we should rely a little less on purely formal accounts. |
| 11210 | Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt] |
| Full Idea: If 'and' and 'but' really are alike in sense, in what might that likeness consist? Some philosophers of classical logic will reply that they share a sense by virtue of sharing a truth table. | |
| From: Ian Rumfitt ("Yes" and "No" [2000]) | |
| A reaction: This is the standard view which Rumfitt sets out to challenge. |
| 11212 | The sense of a connective comes from primitively obvious rules of inference [Rumfitt] |
| Full Idea: A connective will possess the sense that it has by virtue of its competent users' finding certain rules of inference involving it to be primitively obvious. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], III) | |
| A reaction: Rumfitt cites Peacocke as endorsing this view, which characterises the logical connectives by their rules of usage rather than by their pure semantic value. |
| 20457 | Zeno assumes collecting an infinity of things makes an infinite thing [Rovelli] |
| Full Idea: One possible answer is that Zeno is wrong because it is not true that by accumulating an infinite number of things one ends up with an infinite thing. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 01) | |
| A reaction: I do love it when deep and complex ideas are expressed with perfect simplicity. As long as the simple version is correct. |
| 20468 | Quantum mechanics deals with processes, rather than with things [Rovelli] |
| Full Idea: Quantum mechanics teaches us not to think about the world in terms of 'things' which are in this or that state, but in terms of 'processes' instead. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) |
| 20467 | Quantum mechanics describes the world entirely as events [Rovelli] |
| Full Idea: The world of quantum mechanics is not a world of objects: it is a world of events. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) | |
| A reaction: I presume a philosopher is allowed to ask what an 'event' is. Since, as Rovelli tells it, time is eliminated from the picture, events seem to be unanalysable primitives. |
| 15543 | How do things combine to make states of affairs? Constituents can repeat, and fail to combine [Lewis] |
| Full Idea: To me it is mysterious how a state of affairs is made out of its particular and universal constituents. Different states of affairs may have the very same constituents, and the existence of constituents by no means entails the existence of the states. | |
| From: David Lewis (Armstrong on combinatorial possibility [1992], 'What is there') | |
| A reaction: He is rejecting the structure of states of affairs as wholes made of parts. But then mereology was never going to explain the structure of the world. |
| 11214 | We learn 'not' along with affirmation, by learning to either affirm or deny a sentence [Rumfitt] |
| Full Idea: The standard view is that affirming not-A is more complex than affirming the atomic sentence A itself, with the latter determining its sense. But we could learn 'not' directly, by learning at once how to either affirm A or reject A. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], IV) | |
| A reaction: [compressed] This seems fairly anti-Fregean in spirit, because it looks at the psychology of how we learn 'not' as a way of clarifying what we mean by it, rather than just looking at its logical behaviour (and thus giving it a secondary role). |
| 20469 | There are probably no infinities, and 'infinite' names what we do not yet know [Rovelli] |
| Full Idea: 'Infinite', ultimately, is the name that we give to what we do not yet know. Nature appears to be telling us that there is nothing truly infinite. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 11) |
| 20461 | The basic ideas of fields and particles are merged in quantum mechanics [Rovelli] |
| Full Idea: The notions of fields and particles, separated by Faraday and Maxwell, end up merging in quantum mechanics. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) | |
| A reaction: This sounds to me just like Anaximander's 'apeiron' - the unlimited [Rovelli agrees! p.168]. Anaximander predicted the wall which enquiry would hit, but we now have more detail. |
| 20462 | Because it is quantised, a field behaves like a set of packets of energy [Rovelli] |
| Full Idea: Since the energy of the electromagnetic field can take on only certain values, the field behaves like a set of packets of energy. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) |
| 20463 | There are about fifteen particles fields, plus a few force fields [Rovelli] |
| Full Idea: There are about fifteen fields, whose quanta are elementary particles (electrons, quarks, muons, neutrinos, Higgs, and little else), plus a few fields similar to the electromagnetic one, which describe forces at a nuclear scale, with quanta like photons. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) | |
| A reaction: According to Rovelli, this sentence describes the essence of physical reality. |
| 20464 | The world consists of quantum fields, with elementary events happening in spacetime [Rovelli] |
| Full Idea: The world is not made up of fields and particles, but of a single type of entity: the quantum field. There are no longer particles which move in space with the passage of time, but quantum fields whose elementary events happen in spacetime. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) | |
| A reaction: If you are not a scientist, there is (I find) a strong tendency to read and digest stuff like this, and then forget it the next day, because it so far from our experience. Folk like me have to develop two parallel views of the nature of reality. |
| 20459 | Electrons only exist when they interact, and their being is their combination of quantum leaps [Rovelli] |
| Full Idea: Electrons don't always exist. They exist when they interact. They materialize when they collide with something. The quantum leap from one orbit to another constitutes their way of being real. An electron is a combination of leaps between interactions. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) | |
| A reaction: If a philosopher with an Aristotelian interest in the nature of matter wants to grasp the modern view, the electron looks like the thing to focus on. You can feel Rovelli battling here to find formulations that might satisfy a philosopher. |
| 20460 | Electrons are not waves, because their collisions are at a point, and not spread out [Rovelli] |
| Full Idea: Schrödinger's wave is a bad image for an electron, because when a particle collides with something else, it is always at a point: it is never spread out in space like a wave. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04 note) | |
| A reaction: And yet there is the diffusion in the two-slit experiment, which Thomas Young discovered for light. I must take Rovelli's word for this. |
| 20466 | Quantum Theory describes events and possible interactions - not how things are [Rovelli] |
| Full Idea: Quantum Theory does not describe things as they are: it describes how things occur and interact with each other. It doesn't describe where there is a particle but how it shows itself to others. The world of existence is reduced to possible interactions. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) | |
| A reaction: Fans of 'process philosophy' should like this, though he is not denying that there may be facts about how things are - it is just that this is not mentioned in the theory. There is not much point in philosophers yearning to know the reality. |
| 20465 | Nature has three aspects: granularity, indeterminacy, and relations [Rovelli] |
| Full Idea: I think that quantum mechanics has revealed three aspects of the nature of things: granularity, indeterminacy, and the relational structure of the world. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 04) |
| 20458 | The world is just particles plus fields; space is the gravitational field [Rovelli] |
| Full Idea: The world is made up of particles + fields, and nothing else; there is no need to add space as an extra ingredient. Newton's space is the gravitational field. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 03) | |
| A reaction: I get the impression that particles are just bumps or waves in the fields [yes! Rovelli p.110], which would mean there are fields and nothing else. And no one seems to know what a field is. |
| 20470 | Only heat distinguishes past from future [Rovelli] |
| Full Idea: It is always heat and only heat that distinguishes the past from the future. | |
| From: Carlo Rovelli (Reality is Not What it Seems [2014], 12) | |
| A reaction: I can remember the past but not the future - so can that fact be reduced to facts about heat? |