35 ideas
| 16014 | It is controversial whether only 'numerical identity' allows two things to be counted as one [Noonan] |
| Full Idea: 'Numerical identity' implies the controversial view that it is the only identity relation in accordance with which we can properly count (or number) things: x and y are to be properly counted as one just in case they are numerically identical. | |
| From: Harold Noonan (Identity [2009], §1) | |
| A reaction: Noonan cites Geach, presumably to remind us of relative identity, where two things may be one or two, depending on what they are relative to. The one 'guard on the gate' may actually be two men. |
| 16024 | I could have died at five, but the summation of my adult stages could not [Noonan] |
| Full Idea: Persons have different modal properties from the summations of person-stages. …I might have died when I was five. But the maximal summation of person-stages which perdurantists say is me could not have had a temporal extent of a mere five years. | |
| From: Harold Noonan (Identity [2009], §5) | |
| A reaction: Thus the summation of stages seems to fail Leibniz's Law, since truths about a part are not true of the whole. But my foot might be amputated without me being amputated. The objection is the fallacy of composition? |
| 16023 | Stage theorists accept four-dimensionalism, but call each stage a whole object [Noonan] |
| Full Idea: Stage theorists, accepting the ontology of perdurance, modify the semantics to secure the result that fatness is a property of a cat. Every temporal part of a cat (such as Tabby-on-Monday) is a cat. …(but they pay a price over the counting of cats). | |
| From: Harold Noonan (Identity [2009], §5) | |
| A reaction: [Noonan cites Hawley and Sider for this view. The final parenthesis compresses Noonan] I would take the difficulty over counting cats to be fatal to the view. It produces too many cats, or too few, or denies counting altogether. |
| 16015 | Problems about identity can't even be formulated without the concept of identity [Noonan] |
| Full Idea: If identity is problematic, it is difficult to see how the problem could be resolved, since it is difficult to see how a thinker could have the conceptual resources with which to explain the concept of identity whilst lacking that concept itself. | |
| From: Harold Noonan (Identity [2009], §1) | |
| A reaction: I don't think I accept this. We can comprehend the idea of a mind that didn't think in terms of identities (at least for objects). I suppose any relation of a mind to the world has to distinguish things in some way. Does the Parmenidean One have identity? |
| 16017 | Identity is usually defined as the equivalence relation satisfying Leibniz's Law [Noonan] |
| Full Idea: Numerical identity is usually defined as the equivalence relation (or: the reflexive relation) satisfying Leibniz's Law, the indiscernibility of identicals, where everything true of x is true of y. | |
| From: Harold Noonan (Identity [2009], §2) | |
| A reaction: Noonan says this must include 'is identical to x' among the truths, and so is circular |
| 16016 | Identity definitions (such as self-identity, or the smallest equivalence relation) are usually circular [Noonan] |
| Full Idea: Identity can be circularly defined, as 'the relation everything has to itself and to nothing else', …or as 'the smallest equivalence relation'. | |
| From: Harold Noonan (Identity [2009], §2) | |
| A reaction: The first one is circular because 'nothing else' implies identity. The second is circular because it has to quantify over all equivalence relations. (So says Noonan). |
| 16020 | Identity can only be characterised in a second-order language [Noonan] |
| Full Idea: There is no condition in a first-order language for a predicate to express identity, rather than indiscernibility within the resources of the language. Leibniz's Law is statable in a second-order language, so identity can be uniquely characterised. | |
| From: Harold Noonan (Identity [2009], §2) | |
| A reaction: The point is that first-order languages only refer to all objects, but you need to refer to all properties to include Leibniz's Law. Quine's 'Identity, Ostension and Hypostasis' is the source of this idea. |
| 16018 | Indiscernibility is basic to our understanding of identity and distinctness [Noonan] |
| Full Idea: Leibniz's Law (the indiscernibility of identicals) appears to be crucial to our understanding of identity, and, more particularly, to our understanding of distinctness. | |
| From: Harold Noonan (Identity [2009], §2) | |
| A reaction: True, but indiscernibility concerns the epistemology, and identity concerns the ontology. |
| 16019 | Leibniz's Law must be kept separate from the substitutivity principle [Noonan] |
| Full Idea: Leibniz's Law must be clearly distinguished from the substitutivity principle, that if 'a' and 'b' are codesignators they are substitutable salva veritate. | |
| From: Harold Noonan (Identity [2009], §2) | |
| A reaction: He gives a bunch of well-known problem cases for substitutivity. The Morning Star, Giorgione, and the number of planets won't work. Belief contexts, or facts about spelling, may not be substitutable. |
| 8845 | An experience's having propositional content doesn't make it a belief [Pryor] |
| Full Idea: To say that experiences have propositional content is not to say that experiences are beliefs. | |
| From: James Pryor (There is immediate Justification [2005], §4) | |
| A reaction: This is important for opponents of foundationalism, because they will not allow a raw experience to act as a justification on its own. Even if concepts, or even propositions, are offered by experience, the crucial evaluation must preceded knowledge. |
| 8842 | The best argument for immediate justification is not the Regress Argument, but considering examples [Pryor] |
| Full Idea: The best argument for immediate justification is not the Regress Argument, but from considering examples, such as I have a headache, I am raising my arm, I am imagining my grandmother, or seeing how dominoes could fill a chessboard. | |
| From: James Pryor (There is immediate Justification [2005], §3) | |
| A reaction: Most of his examples depend on the fact that they cannot be challenged by anyone else, because they are within his own mind. The dominoes require complex thought. The first two could be erroneous if he was dreaming. |
| 8843 | Impure coherentists accept that perceptions can justify, unlike pure coherentists [Pryor] |
| Full Idea: Pure coherentists claim that a belief can only be justified by its relations to other beliefs; impure coherentists are willing to give some non-beliefs, such as perceptual experiences, a justifying role. | |
| From: James Pryor (There is immediate Justification [2005], §4) | |
| A reaction: I think I would vote for the pure version. The distinction that is needed, I think, is between justification and evidence. You have to surmise causal links and explanations before you can see an experience as evidence, and then justification. |
| 8844 | Coherentism rests on the claim that justifications must be beliefs, with propositional content [Pryor] |
| Full Idea: The Master Argument for coherentism is the claim that a justifier requires asserted propositional content, and that only beliefs represent propositions assertively. | |
| From: James Pryor (There is immediate Justification [2005], §4) | |
| A reaction: I think this claim (which Pryor attacks) is correct. A key point is that almost any experience can be delusional, and in need of critical evaluation. We would even only accept an experience as being necessarily veridical after critical evaluation. |
| 8846 | Reasons for beliefs can be cited to others, unlike a raw headache experience [Pryor] |
| Full Idea: If you have reasons for your belief, they should be considerations you could in principle cite, or give, to someone who doubted or challenged the belief. You can't give some else a non-propositional state like a headache. | |
| From: James Pryor (There is immediate Justification [2005], §6) | |
| A reaction: On the whole I agree, but if someone asked you to justify your claim that there is a beautiful sunset over the harbour, you could just say 'Look!'. Headaches are too private. The person must still see that the sunset is red, and not the window. |
| 8847 | Beliefs are not chosen, but you can seek ways to influence your belief [Pryor] |
| Full Idea: Ordinarily we make no intentional choices about what to believe, but one can choose to believe something, and then seek ways to get oneself to believe it. | |
| From: James Pryor (There is immediate Justification [2005], §7) | |
| A reaction: Deliberately reading the articles of a philosopher that you seem to agree with would be an example. Presumably the belief that this is a good belief and should be given support is not itself voluntarily chosen. Ultimately we are helpless. See Idea 1854. |
| 21181 | Relativity and Quantum theory give very different accounts of forces [Hesketh] |
| Full Idea: General Relativity and quantum mechanics are the two great theories in physics today but they give two very different ideas for how forces work. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 01) | |
| A reaction: Relativity says it is space curvature, and quantum theory says it is particle exchange? But is there a Relativity account of the strong nuclear force? |
| 21183 | Thermodynamics introduced work and entropy, to understand steam engine efficiency [Hesketh] |
| Full Idea: The Laws of Thermodynamics introduced the concepts of entropy and work; put simply, how much useful energy you can really get out of a steam engine. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 03) | |
| A reaction: The point of science by this stage was to introduce measurable and quantifiable concepts |
| 21191 | Photons are B and W° bosons, linked by the Higgs mechanism [Hesketh] |
| Full Idea: The photon is actually a mix of two deeper things, the B and the W°, tied together by the Higgs mechanism. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 06) | |
| A reaction: The B (for 'Boson') transmits a force associated with the 'winding symmetry'. (I record this without properly understanding it.) |
| 21199 | Spinning electric charge produces magnetism, so all fermions are magnets [Hesketh] |
| Full Idea: The muon, like all fermions, spins - and because a spinning electric charge generates a magnetic field all fermions act like tiny bar magnets. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 11) |
| 21189 | Electrons may have smaller components, bound by a new force [Hesketh] |
| Full Idea: Quarks, leptons or bosons may actually be made up of something even smaller, bound together by a conjectural new force. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 05) | |
| A reaction: Electrons are a type of lepton. Compare Idea 21180, from the same book. If electrons are not fundamental, what matters is not some 'stuff' they are made of, but a different force that would bind the ingredients. |
| 21180 | Electrons are fundamental and are not made of anything; they are properties without size [Hesketh] |
| Full Idea: As far as we can tell, electrons (and quarks) are fundamental. They are not small lumps of material, because we could always ask what the material is. The electron just ...is. They are collections of properties, with no apparent size. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 01) | |
| A reaction: This idea from physics HAS to be of interest to philosophers! The bundle theory is discredited for normal objects and for minds, and so is the substrate idea for supporting properties. But rigorous physics accepts a bundle theory. |
| 21182 | Quantum mechanics is our only theory, and is very precise, and repeatedly confirmed [Hesketh] |
| Full Idea: Quantum mechanics is the only working description of the universe that we have. It is amazingly precise, and so far every experimental test has verified its predictions. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 02) | |
| A reaction: I take it from this that quantum mechanics is simply TRUE. Get over it! It will never turn out to be wrong, but may be subsumed within some more fine-grained or extensive theory. |
| 21184 | Physics was rewritten to explain stable electron orbits [Hesketh] |
| Full Idea: Explaining the stable electron orbits would require a complete rewriting of the physics of subatomic particles. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 03) | |
| A reaction: This really looks like a simple and major landmark moment. You can ignore a single anomaly, but not a central feature of your entire theory. |
| 21187 | Virtual particles can't be measured, and can ignore the laws of physics [Hesketh] |
| Full Idea: We can never measure these virtual (transitory) particles directly, and it turns out that they don't even have to obey the laws of physics. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 05) | |
| A reaction: These seems to be the real significance of the Uncertainty Principle. Such particles 'borrow' huge amounts of energy for very short times. |
| 21185 | Colour charge is positive or negative, and also has red, green or blue direction [Hesketh] |
| Full Idea: Colour charge is 'three-dimensional'. As well as the charge having a positive or negative sign, it can also have a direction, and for convenience these three different directions (pointing like a weather vane) are labelled 'red', 'green' and 'blue'. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 04) |
| 21194 | The Standard Model omits gravity, because there are no particles involved [Hesketh] |
| Full Idea: Gravity is not included in the Standard Model because we simply cannot study it using particles. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 09) | |
| A reaction: I'm guessing that Einstein describes how gravity behaves, but not what it is. |
| 21195 | In Supersymmetry the Standard Model simplifies at high energies [Hesketh] |
| Full Idea: Supersymmetry suggest that the Standard Model becomes much simpler at high energies. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 10) |
| 21197 | Standard Model forces are one- two- and three-dimensional [Hesketh] |
| Full Idea: The forces in the Standard Model are built on gauge symmetries, with a one-dimensional charge (like electromagnetism), a two-dimensional charge (the weak force), and a three dimensional charge (the strong force). | |
| From: Gavin Hesketh (The Particle Zoo [2016], 10) | |
| A reaction: See also Idea 21185. |
| 21188 | Quarks and leptons have a weak charge, for the weak force [Hesketh] |
| Full Idea: For the weak force there must be a corresponding 'weak charge', and all the fermions, all the quarks and leptons carry it. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 05) | |
| A reaction: So electrons carry a weak charge, as well as an electromagnetic charge. Like owning several passports. |
| 21186 | Quarks rush wildly around in protons, restrained by the gluons [Hesketh] |
| Full Idea: Inside a proton the quarks are rushing around like caged animals, free to move until they push against the bars to try to escape, when the gluons pull them back in. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 04) |
| 21192 | Neutrinos only interact with the weak force, but decays produce them in huge numbers [Hesketh] |
| Full Idea: Neutrinos only interact with the weak force, which means they barely interact at all, but because the weak force is crucial in the decays of so many other particles, neutrinos are still produced in huge numbers. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 08) | |
| A reaction: They only interact with the W and Z bosons. |
| 21196 | To combine the forces, they must all be the same strength at some point [Hesketh] |
| Full Idea: If all the forces are to combine, at some point they must all be the same strength, and Supersymmetry (SuSy) makes this happen. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 10) | |
| A reaction: This sounds like an impressive reason for favouring supersymmetry - as long as you have an a priori preference for everything combining. |
| 21190 | 'Space' in physics just means location [Hesketh] |
| Full Idea: 'Space' in physics really just means location. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 06) | |
| A reaction: Location can, of course, only be specified relative to something else. Space is really an abstraction, but at least it means there is some sort of background to locate all the fundamental fields. |
| 21193 | The universe is 68% dark energy, 27% dark matter, 5% regular matter [Hesketh] |
| Full Idea: The most precise surveys of the stars and galaxies tell us that the universe is made up of 68% dark energy, 27% dark matter, and just 5% regular matter (the stuff of the Standard Model of particle physics). | |
| From: Gavin Hesketh (The Particle Zoo [2016], 09) | |
| A reaction: Regular matter - that's me, that is. |
| 21198 | If a cosmic theory relies a great deal on fine-tuning basic values, it is probably wrong [Hesketh] |
| Full Idea: If a theory has to rely on excessive 'fine-tuning', a series of extremely unlikely events in order to produce the universe we see around us, then it is extremely unlikely that this theory is correct. | |
| From: Gavin Hesketh (The Particle Zoo [2016], 10) | |
| A reaction: He says the Standard Model has 26 parameters which are only known by experiment, rather than by theory. So instead of saying '...so there is a God', we should say '...so our theory isn't very good'. |