21 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. |
19682 | Internalists are much more interested in evidence than externalists are [McGrew] |
Full Idea: The notion of evidence generally plays a much more significant role in internalist epistemologies than it does in various forms of externalism. | |
From: Timothy McGrew (Evidence [2011], 'Prop..') | |
A reaction: I'm guessing that this is because evidence needs a certain amount of interpretation, whereas raw facts (which externalists seem to rely on) may never even enter a mind. |
19684 | Does spotting a new possibility count as evidence? [McGrew] |
Full Idea: Does the sudden realization of a heretofore unrecognized possibility count as evidence? | |
From: Timothy McGrew (Evidence [2011], 'Evid..') | |
A reaction: [Nice use of 'heretofore'! Why say 'previously' when you can keep these wonderful old English words alive?] This means that we can imagine new evidence ('maybe the murderer was a snake'!). Wrong. The evidence is what suggests the possibility. |
19687 | Absence of evidence proves nothing, and weird claims need special evidence [McGrew] |
Full Idea: Two well know slogans (popularised by Carl Sagan) are 'absence of evidence is not evidence of absence', ...and 'extraordinary claims require extraordinary evidence'. | |
From: Timothy McGrew (Evidence [2011], 'Absence') | |
A reaction: [Sagan was a popular science writer and broadcaster] The second one is something like Hume's argument against miracles. The old problem of the 'missing link' for human evolution embodied the first idea. |
19688 | Every event is highly unlikely (in detail), but may be perfectly plausible [McGrew] |
Full Idea: At a certain level of detail, almost any claim is unprecedented. How likely is 'Matilda won at Scrabble on Thursday with a score of 438 while drinking mint tea'? But there is nothing particularly unbelievable about the claim. | |
From: Timothy McGrew (Evidence [2011], 'Extraordinary') | |
A reaction: A striking idea, which rules out the simplistic idea that we can just assess evidence by its isolated likelihood. Context is crucial. How good is 438? What if she smoked opium? What if there is no Scrabble set on her island? |
19686 | Criminal law needs two separate witnesses, but historians will accept one witness [McGrew] |
Full Idea: An ancient rule in law is that a criminal conviction needs evidence of two independent witnesses, but in history it is assumed that a document deserves the benefit of the doubt if it cannot be independently verified. | |
From: Timothy McGrew (Evidence [2011], 'Interp..') | |
A reaction: [compressed; McGrew's full account qualifies it a bit] A nice observation. One might even be suspicious of the two 'independent' witnesses, if there were lots of other reasons to doubt someon's guilt. A single weird document is also dubious. |
19680 | Maybe all evidence consists of beliefs, rather than of facts [McGrew] |
Full Idea: Some philosophers have been attracted to the view that, strictly speaking, what counts as evidence is not a set of physical objects or even experiences, but rather a set of believed propositions. | |
From: Timothy McGrew (Evidence [2011], 'Prop..') | |
A reaction: This may be right. However, as always, I think animals are a key test. Do animals respond to evidence? Even if they did, they might need to 'make sense' of what they experienced, and even formulate a non-linguistic proposition. |
19681 | If all evidence is propositional, what is the evidence for the proposition? Do we face a regress? [McGrew] |
Full Idea: Taking evidence as propositional may trade one problem for another. If the bloodstain isn't evidence, but 'this is a bloodstain' is evidence, then what serves as evidence for the belief about the bloodstain? Is there an infinite regress? | |
From: Timothy McGrew (Evidence [2011], 'Prop..') | |
A reaction: [compressed] I quite like evidence being propositional, but then find this. I'll retreat to my beloved coherence. I do not endorse Sellars's 'only a belief can justify a belief', because raw experience has to be part of what is coherent. |
19689 | Several unreliable witnesses can give good support, if they all say the same thing [McGrew] |
Full Idea: The testimony of a number of independent witnesses, none of them particularly reliable, who give substantially the same account of some event, may provide a strong argument in its favor. | |
From: Timothy McGrew (Evidence [2011], 'Testimonial') | |
A reaction: A striking point. It obviously works well for panicking people in a crowd during an incident. Does it also apply to independent scientists who are known to cheat? They may not collaborate, but may all want the same result. |
19683 | Narrow evidentialism relies wholly on propositions; the wider form includes other items [McGrew] |
Full Idea: Evidentialism comes in both narrow and wide forms depending on whether evidence is taken to consist only of propositions or of a wider range of items. | |
From: Timothy McGrew (Evidence [2011], 'Evid..') | |
A reaction: [He cites Conee and Feldman for the wide view, which is not restricted to beliefs] You can hardly rely on occurrent beliefs as evidence, so we often have good knowledge with forgotten justification. But such knowledge has been 'weakened'. |
19685 | Falsificationism would be naive if even a slight discrepancy in evidence killed a theory [McGrew] |
Full Idea: Data do not quite speak for themselves, which speaks against a naive form of falsificationism according to which even the slightest mismatch between theory and evidence suffices to overturn a theory. | |
From: Timothy McGrew (Evidence [2011], 'Interp..') | |
A reaction: [He cites Robert Boyle wisely ignoring some data to get a good fit for his graph] |
13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
Full Idea: In a single day there lies open to men of learning more than there ever does to the unenlightened in the longest of lifetimes. | |
From: Posidonius (fragments/reports [c.95 BCE]), quoted by Seneca the Younger - Letters from a Stoic 078 | |
A reaction: These remarks endorsing the infinite superiority of the educated to the uneducated seem to have been popular in late antiquity. It tends to be the religions which discourage great learning, especially in their emphasis on a single book. |
20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |
Full Idea: Posidonius defined time thus: it is an interval of motion, or the measure of speed and slowness. | |
From: report of Posidonius (fragments/reports [c.95 BCE]) by John Stobaeus - Anthology 1.08.42 | |
A reaction: Hm. Can we define motion or speed without alluding to time? Looks like we have to define them as a conjoined pair, which means we cannot fully understand either of them. |