Combining Texts

All the ideas for 'Function and Concept', 'Declaration of the Rights of Man' and 'The Boundary Stones of Thought'

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58 ideas

1. Philosophy / E. Nature of Metaphysics / 6. Metaphysics as Conceptual
Logic doesn't have a metaphysical basis, but nor can logic give rise to the metaphysics [Rumfitt]
     Full Idea: There is surely no metaphysical basis for logic, but equally there is no logical basis for metaphysics, if that implies that we can settle the choice of logic in advance of settling any seriously contested metaphysical-cum-semantic issues.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 7.5)
     A reaction: Is this aimed at Tim Williamson's book on treating modal logic as metaphysics? I agree with the general idea that logic won't deliver a metaphysics. I might want to defend a good metaphysics giving rise to a good logic.
3. Truth / A. Truth Problems / 1. Truth
The idea that there are unrecognised truths is basic to our concept of truth [Rumfitt]
     Full Idea: The realist principle that a statement may be true even though no one is able to recognise its truth is so deeply embedded in our ordinary conception of truth that any account that flouts it is liable to engender confusion.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 5.1)
3. Truth / B. Truthmakers / 7. Making Modal Truths
'True at a possibility' means necessarily true if what is said had obtained [Rumfitt]
     Full Idea: A statement is 'true at a possibility' if, necessarily, things would have been as the statement (actually) says they are, had the possibility obtained.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 6.6)
     A reaction: This is deliberately vague about what a 'possibility' is, but it is intended to be more than a property instantiation, and less than a possible world.
4. Formal Logic / A. Syllogistic Logic / 2. Syllogistic Logic
Frege thought traditional categories had psychological and linguistic impurities [Frege, by Rumfitt]
     Full Idea: Frege rejected the traditional categories as importing psychological and linguistic impurities into logic.
     From: report of Gottlob Frege (Function and Concept [1891]) by Ian Rumfitt - The Boundary Stones of Thought 1.2
     A reaction: Resisting such impurities is the main motivation for making logic entirely symbolic, but it doesn't follow that the traditional categories have to be dropped.
4. Formal Logic / B. Propositional Logic PL / 1. Propositional Logic
Semantics for propositions: 1) validity preserves truth 2) non-contradition 3) bivalence 4) truth tables [Rumfitt]
     Full Idea: The classical semantics of natural language propositions says 1) valid arguments preserve truth, 2) no statement is both true and false, 3) each statement is either true or false, 4) the familiar truth tables.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 1.1)
4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / h. System S5
'Absolute necessity' would have to rest on S5 [Rumfitt]
     Full Idea: If there is such a notion as 'absolute necessity', its logic is surely S5.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 3.3)
     A reaction: There are plenty of people (mainly in the strict empiricist tradition) who don't believe in 'absolute' necessity.
4. Formal Logic / E. Nonclassical Logics / 2. Intuitionist Logic
It is the second-order part of intuitionistic logic which actually negates some classical theorems [Rumfitt]
     Full Idea: Although intuitionistic propositional and first-order logics are sub-systems of the corresponding classical systems, intuitionistic second-order logic affirms the negations of some classical theorems.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 1.1)
Intuitionists can accept Double Negation Elimination for decidable propositions [Rumfitt]
     Full Idea: Double Negation Elimination is a rule of inference which the classicist accepts without restriction, but which the intuitionist accepts only for decidable propositions.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 1.1)
     A reaction: This cures me of my simplistic understanding that intuitionists just reject the rules about double negation.
4. Formal Logic / F. Set Theory ST / 1. Set Theory
Most set theorists doubt bivalence for the Continuum Hypothesis, but still use classical logic [Rumfitt]
     Full Idea: Many set theorists doubt if the Generalised Continuum Hypothesis must be either true or false; certainly, its bivalence is far from obvious. All the same, almost all set theorists use classical logic in their proofs.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 7.2)
     A reaction: His point is that classical logic is usually taken to rest on bivalence. He offers the set theorists a helping hand, by defending classical logic without resorting to bivalence.
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
The iterated conception of set requires continual increase in axiom strength [Rumfitt]
     Full Idea: We are doomed to postulate an infinite sequence of successively stronger axiom systems as we try to spell out what is involved in iterating the power set operation 'as far as possible'.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 9.3)
     A reaction: [W.W. Tait is behind this idea] The problem with set theory, then, especially as a foundation of mathematics, is that it doesn't just expand, but has to keep reinventing itself. The 'large cardinal axioms' are what is referred to.
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / b. Axiom of Extensionality I
A set may well not consist of its members; the empty set, for example, is a problem [Rumfitt]
     Full Idea: There seem strong grounds for rejecting the thesis that a set consists of its members. For one thing, the empty set is a perpetual embarrassment for the thesis.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 8.4)
     A reaction: Rumfitt also says that if 'red' has an extension, then membership of that set must be vague. Extensional sets are precise because their objects are decided in advance, but intensional (or logical) sets, decided by a predicate, can be vague.
A set can be determinate, because of its concept, and still have vague membership [Rumfitt]
     Full Idea: Vagueness in respect of membership is consistent with determinacy of the set's identity, so long as a set's identity is taken to consist, not in its having such-and-such members, but in its being the extension of the concept A.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 8.4)
     A reaction: To be determinate, it must be presumed that there is some test which will decide what falls under the concept. The rule can say 'if it is vague, reject it' or 'if it is vague, accept it'. Without one of those, how could the set have a clear identity?
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / g. Axiom of Powers VI
If the totality of sets is not well-defined, there must be doubt about the Power Set Axiom [Rumfitt]
     Full Idea: Someone who is sympathetic to the thesis that the totality of sets is not well-defined ought to concede that we have no reason to think that the Power Set Axiom is true.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 9.6)
     A reaction: The point is that it is only this Axiom which generates the vast and expanding totality. In principle it is hard, though, to see what is intrinsically wrong with the operation of taking the power set of a set. Hence 'limitation of size'?
5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
Logic is higher-order laws which can expand the range of any sort of deduction [Rumfitt]
     Full Idea: On the conception of logic recommended here, logical laws are higher-order laws that can be applied to expand the range of any deductive principles.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 3.3)
     A reaction: You need the concept of a 'deductive principle' to get this going, but I take it that might be directly known, rather than derived from a law.
5. Theory of Logic / A. Overview of Logic / 6. Classical Logic
The case for classical logic rests on its rules, much more than on the Principle of Bivalence [Rumfitt]
     Full Idea: I think it is a strategic mistake to rest the case for classical logic on the Principle of Bivalence: the soundness of the classical logic rules is far more compelling than the truth of Bivalence.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 1.1)
     A reaction: The 'rules' to which he is referring are those of 'natural deduction', which make very few assumptions, and are intended to be intuitively appealing.
Classical logic rules cannot be proved, but various lines of attack can be repelled [Rumfitt]
     Full Idea: There is not the slightest prospect of proving that the rules of classical logic are sound. ….All that the defender of classical logic can do is scrutinize particular attacks and try to repel them.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 1.1)
     A reaction: This is the agenda for Rumfitt's book.
If truth-tables specify the connectives, classical logic must rely on Bivalence [Rumfitt]
     Full Idea: If we specify the senses of the connectives by way of the standard truth-tables, then we must justify classical logic only by appeal to the Principle of Bivalence.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 7)
     A reaction: Rumfitt proposes to avoid the truth-tables, and hence not to rely on Bivalence for his support of classical logic. He accepts that Bivalence is doubtful, citing the undecidability of the Continuum Hypothesis as a problem instance.
5. Theory of Logic / B. Logical Consequence / 1. Logical Consequence
Logical consequence is a relation that can extended into further statements [Rumfitt]
     Full Idea: Logical consequence, I argue, is distinguished from other implication relations by the fact that logical laws may be applied in extending any implication relation so that it applies among some complex statements involving logical connectives.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 3.3)
     A reaction: He offers implication in electronics as an example of a non-logical implication relation. This seems to indicate that logic must be monotonic, that consequence is transitive, and that the Cut Law always applies.
5. Theory of Logic / B. Logical Consequence / 3. Deductive Consequence |-
Normal deduction presupposes the Cut Law [Rumfitt]
     Full Idea: Our deductive practices seem to presuppose the Cut Law.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 2.3)
     A reaction: That is, if you don't believe that deductions can be transitive (and thus form a successful chain of implications), then you don't really believe in deduction. It remains a well known fact that you can live without the Cut Law.
5. Theory of Logic / D. Assumptions for Logic / 1. Bivalence
When faced with vague statements, Bivalence is not a compelling principle [Rumfitt]
     Full Idea: I do not regard Bivalence, when applied to vague statements, as an intuitively compelling principle which we ought to try to preserve.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 8.7)
     A reaction: The point of Rumfitt's book is to defend classical logic despite failures of bivalence. He also cites undecidable concepts such as the Continuum Hypothesis.
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
In specifying a logical constant, use of that constant is quite unavoidable [Rumfitt]
     Full Idea: There is no prospect whatever of giving the sense of a logical constant without using that very constant, and much else besides, in the metalinguistic principle that specifies that sense.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 1.1)
5. Theory of Logic / E. Structures of Logic / 5. Functions in Logic
First-level functions have objects as arguments; second-level functions take functions as arguments [Frege]
     Full Idea: Just as functions are fundamentally different from objects, so also functions whose arguments are and must be functions are fundamentally different from functions whose arguments are objects. The latter are first-level, the former second-level, functions.
     From: Gottlob Frege (Function and Concept [1891], p.38)
     A reaction: In 1884 he called it 'second-order'. This is the standard distinction between first- and second-order logic. The first quantifies over objects, the second over intensional entities such as properties and propositions.
5. Theory of Logic / E. Structures of Logic / 6. Relations in Logic
Relations are functions with two arguments [Frege]
     Full Idea: Functions of one argument are concepts; functions of two arguments are relations.
     From: Gottlob Frege (Function and Concept [1891], p.39)
     A reaction: Nowadays we would say 'two or more'. Another interesting move in the aim of analytic philosophy to reduce the puzzling features of the world to mathematical logic. There is, of course, rather more to some relations than being two-argument functions.
5. Theory of Logic / H. Proof Systems / 4. Natural Deduction
Introduction rules give deduction conditions, and Elimination says what can be deduced [Rumfitt]
     Full Idea: 'Introduction rules' state the conditions under which one may deduce a conclusion whose dominant logical operator is the connective. 'Elimination rules' state what may be deduced from some premises, where the major premise is dominated by the connective.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 1.1)
     A reaction: So Introduction gives conditions for deduction, and Elimination says what can actually be deduced. If my magic wand can turn you into a frog (introduction), and so I turn you into a frog, how does that 'eliminate' the wand?
5. Theory of Logic / I. Semantics of Logic / 3. Logical Truth
Logical truths are just the assumption-free by-products of logical rules [Rumfitt]
     Full Idea: Gentzen's way of formalising logic has accustomed people to the idea that logical truths are simply the by-products of logical rules, that arise when all the assumptions on which a conclusion rests have been discharged.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 2.5)
     A reaction: This is the key belief of those who favour the natural deduction account of logic. If you really believe in separate logic truths, then you can use them as axioms.
5. Theory of Logic / K. Features of Logics / 10. Monotonicity
Monotonicity means there is a guarantee, rather than mere inductive support [Rumfitt]
     Full Idea: Monotonicity seems to mark the difference between cases in which a guarantee obtains and those where the premises merely provide inductive support for a conclusion.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 2.3)
     A reaction: Hence it is plausible to claim that 'non-monotonic logic' is a contradiction in terms.
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / e. Ordinal numbers
Maybe an ordinal is a property of isomorphic well-ordered sets, and not itself a set [Rumfitt]
     Full Idea: Menzel proposes that an ordinal is something isomorphic well-ordered sets have in common, so while an ordinal can be represented as a set, it is not itself a set, but a 'property' of well-ordered sets.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 9.2)
     A reaction: [C.Menzel 1986] This is one of many manoeuvres available if you want to distance mathematics from set theory.
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / k. Infinitesimals
Infinitesimals do not stand in a determinate order relation to zero [Rumfitt]
     Full Idea: Infinitesimals do not stand in a determinate order relation to zero: we cannot say an infinitesimal is either less than zero, identical to zero, or greater than zero. ….Infinitesimals are so close to zero as to be theoretically indiscriminable from it.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 7.4)
6. Mathematics / B. Foundations for Mathematics / 1. Foundations for Mathematics
Cantor and Dedekind aimed to give analysis a foundation in set theory (rather than geometry) [Rumfitt]
     Full Idea: One of the motivations behind Cantor's and Dedekind's pioneering explorations in the field was the ambition to give real analysis a new foundation in set theory - and hence a foundation independent of geometry.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 9.6)
     A reaction: Rumfitt is inclined to think that the project has failed, although a weaker set theory than ZF might do the job (within limits).
6. Mathematics / C. Sources of Mathematics / 6. Logicism / a. Early logicism
Arithmetic is a development of logic, so arithmetical symbolism must expand into logical symbolism [Frege]
     Full Idea: I am of the opinion that arithmetic is a further development of logic, which leads to the requirement that the symbolic language of arithmetic must be expanded into a logical symbolism.
     From: Gottlob Frege (Function and Concept [1891], p.30)
     A reaction: This may the the one key idea at the heart of modern analytic philosophy (even though logicism may be a total mistake!). Logic and arithmetical foundations become the master of ontology, instead of the servant. The jury is out on the whole enterprise.
7. Existence / A. Nature of Existence / 6. Criterion for Existence
Frege takes the existence of horses to be part of their concept [Frege, by Sommers]
     Full Idea: Frege regarded the existence of horses as a property of the concept 'horse'.
     From: report of Gottlob Frege (Function and Concept [1891]) by Fred Sommers - Intellectual Autobiography 'Realism'
8. Modes of Existence / B. Properties / 10. Properties as Predicates
Frege allows either too few properties (as extensions) or too many (as predicates) [Mellor/Oliver on Frege]
     Full Idea: Frege's theory of properties (which he calls 'concepts') yields too few properties, by identifying coextensive properties, and also too many, by letting every predicate express a property.
     From: comment on Gottlob Frege (Function and Concept [1891]) by DH Mellor / A Oliver - Introduction to 'Properties' §2
     A reaction: Seems right; one extension may have two properties (have heart/kidneys), two predicates might express the same property. 'Cutting nature at the joints' covers properties as well as objects.
9. Objects / A. Existence of Objects / 3. Objects in Thought
The concept 'object' is too simple for analysis; unlike a function, it is an expression with no empty place [Frege]
     Full Idea: I regard a regular definition of 'object' as impossible, since it is too simple to admit of logical analysis. Briefly: an object is anything that is not a function, so that an expression for it does not contain any empty place.
     From: Gottlob Frege (Function and Concept [1891], p.32)
     A reaction: Here is the core of the programme for deriving our ontology from our logic and language, followed through by Russell and Quine. Once we extend objects beyond the physical, it becomes incredibly hard to individuate them.
9. Objects / B. Unity of Objects / 3. Unity Problems / e. Vague objects
An object that is not clearly red or orange can still be red-or-orange, which sweeps up problem cases [Rumfitt]
     Full Idea: A borderline red-orange object satisfies the disjunctive predicate 'red or orange', even though it satisfies neither 'red' or 'orange'. When applied to adjacent bands of colour, the disjunction 'sweeps up' objects which are reddish-orange.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 8.5)
     A reaction: Rumfitt offers a formal principle in support of this. There may be a problem with 'adjacent'. Different colour systems will place different colours adjacent to red. In other examples the idea of 'adjacent' may make no sense. Rumfitt knows this!
The extension of a colour is decided by a concept's place in a network of contraries [Rumfitt]
     Full Idea: On Sainsbury's picture, a colour has an extension that it has by virtue of its place in a network of contrary colour classifications. Something is determined to be 'red' by being a colour incompatible with orange, yellow, green, blue, indigo and violet.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 8.5)
     A reaction: Along with Idea 18839, this gives quite a nice account of vagueness, by requiring a foil to the vague predicate, and using the disjunction of the predicate and its foil to handle anything caught in between them.
10. Modality / A. Necessity / 5. Metaphysical Necessity
Metaphysical modalities respect the actual identities of things [Rumfitt]
     Full Idea: The central characteristic mark of metaphysical necessity is that a metaphysical possibility respects the actual identities of things - in a capacious sense of 'thing'.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 3.4)
     A reaction: He contrast this with logical necessity, and concludes that some truths are metaphysically but not logically necessary, such as 'Hesperus is identical with Phosphorus'. Personally I like the idea of a 'necessity-maker', so that fits.
10. Modality / A. Necessity / 6. Logical Necessity
S5 is the logic of logical necessity [Rumfitt]
     Full Idea: I accept the widely held thesis that S5 is the logic of logical necessity.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 6.4 n16)
     A reaction: It seems plausible that S5 is also the logic of metaphysical necessity, but that does not make them the same thing. The two types of necessity have two different grounds.
10. Modality / B. Possibility / 1. Possibility
Since possibilities are properties of the world, calling 'red' the determination of a determinable seems right [Rumfitt]
     Full Idea: Some philosophers describe the colour scarlet as a determination of the determinable red; since the ways the world might be are naturally taken to be properties of the world, it helps to bear this analogy in mind.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 6.4)
     A reaction: This fits nicely with the disposition accounts of modality which I favour. Hence being 'coloured' is a real property of objects, even in the absence of the name of its specific colour.
If two possibilities can't share a determiner, they are incompatible [Rumfitt]
     Full Idea: Two possibilities are incompatible when no possibility determines both.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 7.1)
     A reaction: This strikes me as just the right sort of language for building up a decent metaphysical picture of the world, which needs to incorporate possibilities as well as actualities.
10. Modality / E. Possible worlds / 1. Possible Worlds / e. Against possible worlds
Possibilities are like possible worlds, but not fully determinate or complete [Rumfitt]
     Full Idea: Possibilities are things of the same general character as possible worlds, on one popular conception of the latter. They differ from worlds, though, in that they are not required to be fully determinate or complete.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 6)
     A reaction: A rather promising approach to such things, even though a possibility is fairly determinate at its core, but very vague at the edges. It is possible that the UK parliament might be located in Birmingham, for example. Is this world 'complete'?
11. Knowledge Aims / A. Knowledge / 2. Understanding
Medieval logicians said understanding A also involved understanding not-A [Rumfitt]
     Full Idea: Mediaeval logicians had a principle, 'Eadem est scientia oppositorum': in order to attain a clear conception of what it is for A to be the case, one needs to attain a conception of what it is for A not to be the case.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 7.2)
     A reaction: Presumably 'understanding' has to be a fairly comprehensive grasp of the matter, so understanding the negation sounds like a reasonable requirement for the real thing.
13. Knowledge Criteria / B. Internal Justification / 3. Evidentialism / a. Evidence
In English 'evidence' is a mass term, qualified by 'little' and 'more' [Rumfitt]
     Full Idea: In English, the word 'evidence' behaves as a mass term: we speak of someone's having little evidence for an assertion, and of one thinker's having more evidence than another for a claim. One the other hand, we also speak of 'pieces' of evidence.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 5.2)
     A reaction: And having 'more' evidence does not mean having a larger number of pieces of evidence, so it really is like an accumulated mass.
18. Thought / D. Concepts / 3. Ontology of Concepts / c. Fregean concepts
Concepts are the ontological counterparts of predicative expressions [Frege, by George/Velleman]
     Full Idea: Concepts, for Frege, are the ontological counterparts of predicative expressions.
     From: report of Gottlob Frege (Function and Concept [1891]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.2
     A reaction: That sounds awfully like what many philosophers call 'universals'. Frege, as a platonist (at least about numbers), I would take to be in sympathy with that. At least we can say that concepts seem to be properties.
An assertion about the concept 'horse' must indirectly speak of an object [Frege, by Hale]
     Full Idea: Frege had a notorious difficulty over the concept 'horse', when he suggests that if we wish to assert something about a concept, we are obliged to proceed indirectly by speaking of an object that represents it.
     From: report of Gottlob Frege (Function and Concept [1891], Ch.2.II) by Bob Hale - Abstract Objects
     A reaction: This sounds like the thin end of a wedge. The great champion of objects is forced to accept them here as a façon de parler, when elsewhere they have ontological status.
A concept is a function whose value is always a truth-value [Frege]
     Full Idea: A concept in logic is closely connected with what we call a function. Indeed, we may say at once: a concept is a function whose value is always a truth-value. ..I give the name 'function' to what is meant by the 'unsaturated' part.
     From: Gottlob Frege (Function and Concept [1891], p.30)
     A reaction: So a function becomes a concept when the variable takes a value. Problems arise when the value is vague, or the truth-value is indeterminable.
18. Thought / D. Concepts / 4. Structure of Concepts / a. Conceptual structure
Unlike objects, concepts are inherently incomplete [Frege, by George/Velleman]
     Full Idea: For Frege, concepts differ from objects in being inherently incomplete in nature.
     From: report of Gottlob Frege (Function and Concept [1891]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.2
     A reaction: This is because they are 'unsaturated', needing a quantified variable to complete the sentence. This could be a pointer towards Quine's view of properties, as simply an intrinsic feature of predication about objects, with no separate identity.
19. Language / A. Nature of Meaning / 4. Meaning as Truth-Conditions
We understand conditionals, but disagree over their truth-conditions [Rumfitt]
     Full Idea: It is striking that our understanding of conditionals is not greatly impeded by widespread disagreement about their truth-conditions.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 4.2)
     A reaction: Compare 'if you dig there you might find gold' with 'if you dig there you will definitely find gold'. The second but not the first invites 'how do you know that?', implying truth. Two different ifs.
19. Language / B. Reference / 5. Speaker's Reference
I may regard a thought about Phosphorus as true, and the same thought about Hesperus as false [Frege]
     Full Idea: From sameness of meaning there does not follow sameness of thought expressed. A fact about the Morning Star may express something different from a fact about the Evening Star, as someone may regard one as true and the other false.
     From: Gottlob Frege (Function and Concept [1891], p.14)
     A reaction: This all gets clearer if we distinguish internalist and externalist theories of content. Why take sides on this? Why not just ask 'what is in the speaker's head?', 'what does the sentence mean in the community?', and 'what is the corresponding situation?'
19. Language / F. Communication / 3. Denial
The truth grounds for 'not A' are the possibilities incompatible with truth grounds for A [Rumfitt]
     Full Idea: The truth-grounds of '¬A' are precisely those possibilities that are incompatible with any truth-ground of A.
     From: Ian Rumfitt (The Boundary Stones of Thought [2015], 7.1)
     A reaction: This is Rumfitt's proposal for the semantics of 'not', based on the central idea of a possibility, rather than a possible world. The incompatibility tracks back to an absence of shared grounding.
24. Political Theory / B. Nature of a State / 1. Purpose of a State
The purpose of society is to protect the rights of liberty, property, security and resistance [Mirabeau/committee]
     Full Idea: The aim of all political associations is the conservation of the natural and imprescriptible rights of man. These rights are liberty, property, security, and resistance to oppression.
     From: Mirabeau and committee (Declaration of the Rights of Man [1789], 02)
     A reaction: Radical thinkers will obviously be doubtful about property being on the list, because that entrenches huge inequalities, between peasants and their landlords. Resistance to oppression will bother the likes of Edmund Burke.
24. Political Theory / B. Nature of a State / 2. State Legitimacy / d. General will
The law expresses the general will, and all citizens can participate [Mirabeau/committee]
     Full Idea: The law is the expression of the general will. All citizens have the right to take part in person or through their representatives in its formulation. It must be the same for all, whether it protects or whether it punishes.
     From: Mirabeau and committee (Declaration of the Rights of Man [1789], 06)
     A reaction: Now you are wondering who qualifies as a 'citizen'. Rousseau would have been excited until he found that the citizens could send 'representatives', instead of voting themselves. Rousseau aimed at foundational laws, not all of the laws.
24. Political Theory / B. Nature of a State / 3. Constitutions
There is only a constitution if rights are assured, and separation of powers defined [Mirabeau/committee]
     Full Idea: Any society in which the guarantee of Rights is not assured, nor the separation of Power determined, has no Constitution.
     From: Mirabeau and committee (Declaration of the Rights of Man [1789], 16)
     A reaction: I wonder if they had Britain in mind with this one? The British latched onto Magna Carta in the early 19th century, because it offered some semblance of a constitution.
25. Social Practice / A. Freedoms / 2. Freedom of belief
No one should be molested for their opinions, if they do not disturb the established order [Mirabeau/committee]
     Full Idea: No man is to be molested on account of his opinions, even his religious opinions, provided that their manifestation does not disturb the public order established by law.
     From: Mirabeau and committee (Declaration of the Rights of Man [1789], 10)
     A reaction: Virtually any opinion will 'disturb' the established order a little bit, so this gives the option of suppressing quite mild beliefs, on the grounds of their small disturbance. It is still a wonderful proposal, though.
25. Social Practice / A. Freedoms / 3. Free speech
Free speech is very precious, and everyone may speak and write freely (but take responsibility for it) [Mirabeau/committee]
     Full Idea: The free communication of thoughts and opinions is one of man's most precious rights. Every citizen may therefore speak, write, and publish freely; except that he shall be responsible for the abuse of that freedom in cases determined by law.
     From: Mirabeau and committee (Declaration of the Rights of Man [1789], 11)
     A reaction: Wonderful, and very nicely expressed. Tom Paine will have been a huge influence on this clause.
25. Social Practice / B. Equalities / 2. Political equality
All citizens are eligible for roles in the state, purely on the basis of merit [Mirabeau/committee]
     Full Idea: All citizens being equal in the eyes of the law are equally eligible to all honours, offices, and public employments, according to their abilities and without other distinction than that of their virtues and talents.
     From: Mirabeau and committee (Declaration of the Rights of Man [1789], 06)
     A reaction: This proclamation of meritocracy must have rung bells around the cities of Europe, and was a reason why many people enjoyed being invaded by Napoleon.
25. Social Practice / C. Rights / 4. Property rights
Property is a sacred right, breached only when essential, and with fair compensation [Mirabeau/committee]
     Full Idea: Since property is an inviolable and sacred right, no man may be deprived of it except when public necessity, lawfully constituted, evidently requires it; and on condition that a just indemnity be paid in advance.
     From: Mirabeau and committee (Declaration of the Rights of Man [1789], 17)
     A reaction: This covers compulsory purchase orders. Is the ownership of slaves inviolable? Will aristocrats be compensated for the confiscation of their vast estates?
25. Social Practice / E. Policies / 4. Taxation
Everyone must contribute to the state's power and administration, in just proportion [Mirabeau/committee]
     Full Idea: For the maintenance of public force and the expenses of administration, a common contribution is indispensable. It must be equally apportioned among all citizens according to their abilities.
     From: Mirabeau and committee (Declaration of the Rights of Man [1789], 13)
     A reaction: Presumably this enshrines graduated income tax, an eighteenth century invention. Could you contribute just by your labour, or by fighting for the army? Those may be greater contributions than mere money.
28. God / B. Proving God / 2. Proofs of Reason / b. Ontological Proof critique
The Ontological Argument fallaciously treats existence as a first-level concept [Frege]
     Full Idea: The ontological proof of God's existence suffers from the fallacy of treating existence as a first-level concept.
     From: Gottlob Frege (Function and Concept [1891], p.38 n)
     A reaction: [See Idea 8490 for first- and second-order functions] This is usually summarised as the idea that existence is a quantifier rather than a predicate.