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### Ideas of Fraser MacBride, by Text

#### [British, fl. 2004, Reader at Birkbeck College, London, then at Cambridge, then Manchester.]

 2007 Structuralism Reconsidered
 §1 p.563 8923 Numbers are identified by their main properties and relations, involving the successor function Full Idea: The mathematically significant properties and relations of natural numbers arise from the successor function that orders them; the natural numbers are identified simply as the objects that answer to this basic function. From: Fraser MacBride (Structuralism Reconsidered [2007], §1) A reaction: So Julius Caesar would be a number if he was the successor of Pompey the Great? I would have thought that counting should be mentioned - cardinality as well as ordinality. Presumably Peano's Axioms are being referred to.
 §3 p.585 8926 For mathematical objects to be positions, positions themselves must exist first Full Idea: The identification of mathematical objects with positions in structures rests upon the prior credibility of the thesis that positions are objects in their own right. From: Fraser MacBride (Structuralism Reconsidered [2007], §3) A reaction: Sounds devastating, but something has to get the whole thing off the ground. This is why Resnik's word 'patterns' is so appealing. Patterns stare you in the face, and they don't change if all the objects making it up are replaced by others.
 2013 Truthmakers
 1.1 p.3 18466 If truthmaking is classical entailment, then anything whatsoever makes a necessary truth Full Idea: If a truthmaker entails its truth, this threatens to over-generate truth-makers for necessary truths - at least if the entailment is classical. It's a feature of this notion that anything whatsoever entails a given necessary truth. From: Fraser MacBride (Truthmakers [2013], 1.1) A reaction: This is a good reason to think that the truth-making relation does not consist of logical entailment.
 1.6 p.10 18471 Different types of 'grounding' seem to have no more than a family resemblance relation Full Idea: The concept of 'grounding' appears to cry out for treatment as a family resemblance concept, a concept whose instances have no more in common than different games do. From: Fraser MacBride (Truthmakers [2013], 1.6) A reaction: I like the word 'determinations', though MacBride's point my also apply to that. I take causation to be one species of determination, and truth-making to be another. They form a real family, with no adoptees.
 1.6 p.10 18472 Which has priority - 'grounding' or 'truth-making'? Full Idea: Some philosophers define 'grounding' in terms of 'truth-making', rather than the other way around. From: Fraser MacBride (Truthmakers [2013], 1.6) A reaction: [Cameron exemplifies the first, and Schaffer the second] I would have thought that grounding was in the world, but truth-making required the introduction of propositions about the world by minds, so grounding is prior. Schaffer is right.
 2.1 p.11 18473 'Maximalism' says every truth has an actual truthmaker Full Idea: The principle of 'maximalism' is that for every truth, then there must be something in the world that makes it true. From: Fraser MacBride (Truthmakers [2013], 2.1) A reaction: That seems to mean that no truths can be uttered about anything which is not in the world. If I say 'pigs might have flown', that isn't about the modal profile of actual pigs, it is about what might have resulted from that profile.
 2.1.1 p.11 18474 Does 'this sentence has no truth-maker' have a truth-maker? Reductio suggests it can't have Full Idea: If the sentence 'This sentence has no truth-maker' has a truth-maker, then it must be true. But then what it says must be the case, so it has no truth-maker. Hence by reductio the sentence has no truth-maker. From: Fraser MacBride (Truthmakers [2013], 2.1.1) A reaction: [Argument proposed by Peter Milne 2005] Rodriguez-Pereyra replies that the sentence is meaningless, so that it can't possibly be true. The Liar sentence is also said to be meaningless. The argument opposes Maximalism.
 2.1.3 p.12 18475 Russell allows some complex facts, but Wittgenstein only allows atomic facts Full Idea: The logical atomism of Russell admitted some logically complex facts but not others - in contrast to Wittgenstein's version which admitted only atomic facts. From: Fraser MacBride (Truthmakers [2013], 2.1.3) A reaction: For truthmakers, it looks as if the Wittgenstein version might do a better job (e.g. with negative truths). I quite like the Russell approach, where complex facts underwrite the logical connectives. Disjunctive, negative, conjunctive, hypothetical facts.
 2.1.4 p.13 18476 'A is F' may not be positive ('is dead'), and 'A is not-F' may not be negative ('is not blind') Full Idea: Statements of the form 'a is F' aren't invariably positive ('a is dead'), and nor are statements of the form 'a isn't F' ('a isn't blind') always negative. From: Fraser MacBride (Truthmakers [2013], 2.1.4) A reaction: The point is that the negation may be implicit in the predicate. There are many ways to affirm or deny something, other than by use of the standard syntax.
 2.1.4.1 p.14 18478 Wittgenstein's plan to show there is only logical necessity failed, because of colours Full Idea: It is almost universally acknowledged that Wittgenstein's plan to show all necessity is logical necessity ended in failure - indeed foundered upon the very problem of explaining colour incompatibilities. From: Fraser MacBride (Truthmakers [2013], 2.1.4.1) A reaction: I'm not sure whether you can 'show' that colour incompatibility is some sort of necessity, though intuitively it seems so. I'm thinking that 'necessity' is a unitary concept, with a wide variety of sources generating it.
 2.1.4.1 p.14 18479 There are different types of truthmakers for different types of negative truth Full Idea: We recognise that what makes it true that there is no oil in this engine is different from what makes it true that there are no dodos left. From: Fraser MacBride (Truthmakers [2013], 2.1.4.1) A reaction: This looks like a local particular negation up against a universal negation. I'm not sure there is a big difference between 'my dodo's gone missing' (like my oil), and 'all the dodos have gone permanently missing'.
 2.1.4.1 p.14 18477 There aren't enough positive states out there to support all the negative truths Full Idea: It's not obvious that there are enough positive states out there to underwrite all the negative truths. Even though it may be true that this liquid is odourless this needn't be because there's something further about it that excludes its being odourless. From: Fraser MacBride (Truthmakers [2013], 2.1.4.1) A reaction: What is the ontological status of all these hypothetical truths? What is the truthmaker for 'a trillion trillion negative truths exist'? What is the status of 'this is not not-red'?
 2.1.4.2 p.16 18480 Maybe it only exists if it is a truthmaker (rather than the value of a variable)? Full Idea: 'To be is to be a truth-maker' has been proposed as a replacement the standard conception of ontological commitment, that to be is to be the value of a variable. From: Fraser MacBride (Truthmakers [2013], 2.1.4.2) A reaction: [He cites Ross Cameron 2008] Unconvincing. What does it mean to say that some remote unexperienced bit of the universe 'makes truths'? How many truths? Where do these truths reside when they aren't doing anything useful?
 2.2 p.17 18481 Maximalism follows Russell, and optimalism (no negative or universal truthmakers) follows Wittgenstein Full Idea: If maximalism is intellectual heir to Russell's logical atomism, then 'optimalism' (the denial that universal and negative statements need truth-makers) is heir to Wittgenstein's version, where only atomic propositions represent states of affairs. From: Fraser MacBride (Truthmakers [2013], 2.2) A reaction: Wittgenstein's idea is that you can use the logical connectives to construct all the other universal and negative facts. 'Optimalism' restricts truthmaking to atomic statements.
 2.2 p.18 18482 Optimalists say that negative and universal are true 'by default' from the positive truths Full Idea: Optimalists say that negative truths are 'true by default' (having the opposite truth value of p), and universal truths are too. Universal truths are equivalent to negative existential truths, which are true by default. From: Fraser MacBride (Truthmakers [2013], 2.2) A reaction: The background idea is Wittgenstein's, that if p is false, then not-p is true by default, without anyone having to assert the negation. This strikes me as a very promising approach to truthmaking. See Simons 2008.
 2.4.1 p.20 18483 The main idea of truth-making is that what a proposition is about is what matters Full Idea: According the Lewis, the kernel of truth in truth-making is the idea that propositions have a subject matter. They are about things, so whether they are true or false depends on how those things stand. From: Fraser MacBride (Truthmakers [2013], 2.4.1) A reaction: [Lewis 'Things Qua Truth-makers' 2003] That sounds like the first step in the story, rather than the 'kernel' of the truth-making approach.
 3.1 p.22 18484 Phenomenalists, behaviourists and presentists can't supply credible truth-makers Full Idea: For Martin the fatal error of phenomenalists was their inability to supply credible truth-makers for truths about unobserved objects; the same error afflicted Ryle's behaviourism, ...and Prior's Presentism (for past-tensed and future-tensed truths). From: Fraser MacBride (Truthmakers [2013], 3.1) A reaction: This seems to be the original motivation for the modern rise of the truthmaker idea. Personally I find 'Napoleon won at Austerlitz' is a perfectly good past-tensed truthmaker which is compatible with presentism. Truth-making is an excellent challenge.
 3.1 p.22 18485 Even idealists could accept truthmakers, as mind-dependent Full Idea: Even an idealist could accept that there are truth-makers whilst thinking of them as mind-dependent entities. From: Fraser MacBride (Truthmakers [2013], 3.1) A reaction: This undercuts anyone (me, perhaps?) who was hoping to prop up their robust realism with an angry demand to be shown the truthmakers.
 3.3 p.23 18486 We might define truth as arising from the truth-maker relation Full Idea: We might define truth using the truth-maker relation, albeit in a roundabout way, according to the pattern of saying 'S is true' is equivalent to 'there is something which makes S true'. From: Fraser MacBride (Truthmakers [2013], 3.3) A reaction: [MacBride gives it more algebraically, but I prefer English!] You would need to explain 'truth-making' without reference to truth. Horwich objects, reasonably, that ordinary people grasp 'truth' much more clearly than 'truth-making'. Bad idea, I think.
 3.7 p.26 18489 Connectives link sentences without linking their meanings Full Idea: The 'connectives' are expressions that link sentences but without expressing a relation that holds between the states of affairs, facts or tropes that these sentences denote. From: Fraser MacBride (Truthmakers [2013], 3.7) A reaction: MacBride notes that these contrast with ordinary verbs, which do express meaningful relations.
 3.7 p.26 18490 Maybe 'makes true' is not an active verb, but just a formal connective like 'because'? Full Idea: Maybe the truth-maker panegyrists have misconstrued the logical form of 'makes true'. They have taken it to be a verb like 'x hits y', when really it is akin to the connective '→' or 'because'. From: Fraser MacBride (Truthmakers [2013], 3.7) A reaction: [He cites Melia 2005] This isn't any sort of refutation of truth-making, but an offer of how to think of the phenomenon if you reject the big principle. I like truth-making, but resist the 'makes' that brings unthought propositions into existence.
 3.8 p.27 18493 Truthmaker talk of 'something' making sentences true, which presupposes objectual quantification Full Idea: When supporters of truth-making talk of 'something' which makes a sentence true, they make the assumption that it is an objectual quantifier in name position. From: Fraser MacBride (Truthmakers [2013], 3.8) A reaction: We might say, more concisely, that they are 'reifying' the something. This makes it sound as if Armstrong and Bigelow have made a mistake, but that are simply asserting that this particular quantification is indeed objectual.
 2016 Relations
 1 p.2 21352 'Multigrade' relations are those lacking a fixed number of relata Full Idea: A 'unigrade' relation R has a definite degree or adicity: R is binary, or ternary....or n-ary (for some unique n). By contrast a relation is 'multigrade' if it fails to be unigrade. Causation appears to be multigrade. From: Fraser MacBride (Relations [2016], 1) A reaction: He also cites entailment, which may have any number of premises.
 3 p.5 21353 Internal relations are fixed by existences, or characters, or supervenience on characters Full Idea: Internal relations are determined either by the mere existence of the things they relate, or by their intrinsic characters, or they supervene on the intrinsic characters of the things they relate. From: Fraser MacBride (Relations [2016], 3) A reaction: Suggesting that they 'supervene' doesn't explain anything (and supervenience never explains anything). I vote for the middle one - the intrinsic character. It has to be something about the existence, and not the mere fact of existence.
 3 p.5 21354 It may be that internal relations like proportion exist, because we directly perceive it Full Idea: Some philosophers maintain that we literally perceive proportions and other internal relations. These relations must exist, otherwise we couldn't perceive them. From: Fraser MacBride (Relations [2016], 3) A reaction: [He cites Mulligan 1991, and Hochberg 2013:232] This seems a rather good point. You can't perceive the differing heights of two people, yet fail to perceive that one is taller. You also perceive 'below', which is external.