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All the ideas for 'Causation', 'The Morality of Happiness' and 'On Formally Undecidable Propositions'

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41 ideas

3. Truth / F. Semantic Truth / 1. Tarski's Truth / a. Tarski's truth definition
Prior to Gödel we thought truth in mathematics consisted in provability [Gödel, by Quine]
     Full Idea: Gödel's proof wrought an abrupt turn in the philosophy of mathematics. We had supposed that truth, in mathematics, consisted in provability.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Willard Quine - Forward to Gödel's Unpublished
     A reaction: This explains the crisis in the early 1930s, which Tarski's theory appeared to solve.
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
Gödel show that the incompleteness of set theory was a necessity [Gödel, by Hallett,M]
     Full Idea: Gödel's incompleteness results of 1931 show that all axiom systems precise enough to satisfy Hilbert's conception are necessarily incomplete.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Michael Hallett - Introduction to Zermelo's 1930 paper p.1215
     A reaction: [Hallett italicises 'necessarily'] Hilbert axioms have to be recursive - that is, everything in the system must track back to them.
5. Theory of Logic / K. Features of Logics / 1. Axiomatisation
The limitations of axiomatisation were revealed by the incompleteness theorems [Gödel, by Koellner]
     Full Idea: The inherent limitations of the axiomatic method were first brought to light by the incompleteness theorems.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Peter Koellner - On the Question of Absolute Undecidability 1.1
5. Theory of Logic / K. Features of Logics / 2. Consistency
Second Incompleteness: nice theories can't prove their own consistency [Gödel, by Smith,P]
     Full Idea: Second Incompleteness Theorem: roughly, nice theories that include enough basic arithmetic can't prove their own consistency.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Peter Smith - Intro to Gödel's Theorems 1.5
     A reaction: On the face of it, this sounds less surprising than the First Theorem. Philosophers have often noticed that it seems unlikely that you could use reason to prove reason, as when Descartes just relies on 'clear and distinct ideas'.
5. Theory of Logic / K. Features of Logics / 3. Soundness
If soundness can't be proved internally, 'reflection principles' can be added to assert soundness [Gödel, by Halbach/Leigh]
     Full Idea: Gödel showed PA cannot be proved consistent from with PA. But 'reflection principles' can be added, which are axioms partially expressing the soundness of PA, by asserting what is provable. A Global Reflection Principle asserts full soundness.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Halbach,V/Leigh,G.E. - Axiomatic Theories of Truth (2013 ver) 1.2
     A reaction: The authors point out that this needs a truth predicate within the language, so disquotational truth won't do, and there is a motivation for an axiomatic theory of truth.
5. Theory of Logic / K. Features of Logics / 5. Incompleteness
Gödel's First Theorem sabotages logicism, and the Second sabotages Hilbert's Programme [Smith,P on Gödel]
     Full Idea: Where Gödel's First Theorem sabotages logicist ambitions, the Second Theorem sabotages Hilbert's Programme.
     From: comment on Kurt Gödel (On Formally Undecidable Propositions [1931]) by Peter Smith - Intro to Gödel's Theorems 36
     A reaction: Neo-logicism (Crispin Wright etc.) has a strategy for evading the First Theorem.
The undecidable sentence can be decided at a 'higher' level in the system [Gödel]
     Full Idea: My undecidable arithmetical sentence ...is not at all absolutely undecidable; rather, one can always pass to 'higher' systems in which the sentence in question is decidable.
     From: Kurt Gödel (On Formally Undecidable Propositions [1931]), quoted by Peter Koellner - On the Question of Absolute Undecidability 1.1
     A reaction: [a 1931 MS] He says the reals are 'higher' than the naturals, and the axioms of set theory are higher still. The addition of a truth predicate is part of what makes the sentence become decidable.
6. Mathematics / A. Nature of Mathematics / 1. Mathematics
There can be no single consistent theory from which all mathematical truths can be derived [Gödel, by George/Velleman]
     Full Idea: Gödel's far-reaching work on the nature of logic and formal systems reveals that there can be no single consistent theory from which all mathematical truths can be derived.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.8
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / g. Incompleteness of Arithmetic
Gödel showed that arithmetic is either incomplete or inconsistent [Gödel, by Rey]
     Full Idea: Gödel's theorem states that either arithmetic is incomplete, or it is inconsistent.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Georges Rey - Contemporary Philosophy of Mind 8.7
First Incompleteness: arithmetic must always be incomplete [Gödel, by Smith,P]
     Full Idea: First Incompleteness Theorem: any properly axiomatised and consistent theory of basic arithmetic must remain incomplete, whatever our efforts to complete it by throwing further axioms into the mix.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Peter Smith - Intro to Gödel's Theorems 1.2
     A reaction: This is because it is always possible to formulate a well-formed sentence which is not provable within the theory.
Arithmetical truth cannot be fully and formally derived from axioms and inference rules [Gödel, by Nagel/Newman]
     Full Idea: The vast continent of arithmetical truth cannot be brought into systematic order by laying down a fixed set of axioms and rules of inference from which every true mathematical statement can be formally derived. For some this was a shocking revelation.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by E Nagel / JR Newman - Gödel's Proof VII.C
     A reaction: Good news for philosophy, I'd say. The truth cannot be worked out by mechanical procedures, so it needs the subtle and intuitive intelligence of your proper philosopher (Parmenides is the role model) to actually understand reality.
Gödel's Second says that semantic consequence outruns provability [Gödel, by Hanna]
     Full Idea: Gödel's Second Incompleteness Theorem says that true unprovable sentences are clearly semantic consequences of the axioms in the sense that they are necessarily true if the axioms are true. So semantic consequence outruns provability.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Robert Hanna - Rationality and Logic 5.3
First Incompleteness: a decent consistent system is syntactically incomplete [Gödel, by George/Velleman]
     Full Idea: First Incompleteness Theorem: If S is a sufficiently powerful formal system, then if S is consistent then S is syntactically incomplete.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6
     A reaction: Gödel found a single sentence, effectively saying 'I am unprovable in S', which is neither provable nor refutable in S.
Second Incompleteness: a decent consistent system can't prove its own consistency [Gödel, by George/Velleman]
     Full Idea: Second Incompleteness Theorem: If S is a sufficiently powerful formal system, then if S is consistent then S cannot prove its own consistency
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6
     A reaction: This seems much less surprising than the First Theorem (though it derives from it). It was always kind of obvious that you couldn't use reason to prove that reason works (see, for example, the Cartesian Circle).
There is a sentence which a theory can show is true iff it is unprovable [Gödel, by Smith,P]
     Full Idea: The original Gödel construction gives us a sentence that a theory shows is true if and only if it satisfies the condition of being unprovable-in-that-theory.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Peter Smith - Intro to Gödel's Theorems 20.5
'This system can't prove this statement' makes it unprovable either way [Gödel, by Clegg]
     Full Idea: An approximation of Gödel's Theorem imagines a statement 'This system of mathematics can't prove this statement true'. If the system proves the statement, then it can't prove it. If the statement can't prove the statement, clearly it still can't prove it.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Brian Clegg - Infinity: Quest to Think the Unthinkable Ch.15
     A reaction: Gödel's contribution to this simple idea seems to be a demonstration that formal arithmetic is capable of expressing such a statement.
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / d. Predicativism
Realists are happy with impredicative definitions, which describe entities in terms of other existing entities [Gödel, by Shapiro]
     Full Idea: Gödel defended impredicative definitions on grounds of ontological realism. From that perspective, an impredicative definition is a description of an existing entity with reference to other existing entities.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Stewart Shapiro - Thinking About Mathematics 5.3
     A reaction: This is why constructivists must be absolutely precise about definition, where realists only have to do their best. Compare building a car with painting a landscape.
8. Modes of Existence / C. Powers and Dispositions / 2. Powers as Basic
If dispositions are more fundamental than causes, then they won't conceptually reduce to them [Bird on Lewis]
     Full Idea: Maybe a disposition is a more fundamental notion than a cause, in which case Lewis has from the very start erred in seeking a causal analysis, in a traditional, conceptual sense, of disposition terms.
     From: comment on David Lewis (Causation [1973]) by Alexander Bird - Nature's Metaphysics 2.2.8
     A reaction: Is this right about Lewis? I see him as reducing both dispositions and causes to a set of bald facts, which exist in possible and actual worlds. Conditionals and counterfactuals also suffer the same fate.
10. Modality / B. Possibility / 9. Counterfactuals
For true counterfactuals, both antecedent and consequent true is closest to actuality [Lewis]
     Full Idea: A counterfactual is non-vacuously true iff it takes less of a departure from actuality to make the consequent true along with the antecedent than it does to make the antecedent true without the consequent.
     From: David Lewis (Causation [1973], p.197)
     A reaction: Almost every theory proposed by Lewis hangs on the meaning of the word 'close', as used here. If you visited twenty Earth-like worlds (watch Startrek?), it would be a struggle to decide their closeness to ours in rank order.
16. Persons / F. Free Will / 6. Determinism / a. Determinism
Determinism says there can't be two identical worlds up to a time, with identical laws, which then differ [Lewis]
     Full Idea: By determinism I mean that the prevailing laws of nature are such that there do not exist any two possible worlds which are exactly alike up to that time, which differ thereafter, and in which those laws are never violated.
     From: David Lewis (Causation [1973], p.196)
     A reaction: This would mean that the only way an action of free will could creep in would be if it accepted being a 'violation' of the laws of nature. Fans of free will would probably prefer to call it a 'natural' phenomenon. I'm with Lewis.
17. Mind and Body / C. Functionalism / 2. Machine Functionalism
Basic logic can be done by syntax, with no semantics [Gödel, by Rey]
     Full Idea: Gödel in his completeness theorem for first-order logic showed that a certain set of syntactically specifiable rules was adequate to capture all first-order valid arguments. No semantics (e.g. reference, truth, validity) was necessary.
     From: report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Georges Rey - Contemporary Philosophy of Mind 8.2
     A reaction: This implies that a logic machine is possible, but we shouldn't raise our hopes for proper rationality. Validity can be shown for purely algebraic arguments, but rationality requires truth as well as validity, and that needs propositions and semantics.
19. Language / D. Propositions / 2. Abstract Propositions / b. Propositions as possible worlds
A proposition is a set of possible worlds where it is true [Lewis]
     Full Idea: I identify a proposition with the set of possible worlds where it is true.
     From: David Lewis (Causation [1973], p.193)
     A reaction: As it stands, I'm baffled by this. How can 'it is raining' be a set of possible worlds? I assume it expands to refer to the truth-conditions, among possibilities as well as actualities. 'It is raining' fits all worlds where it is raining.
20. Action / C. Motives for Action / 3. Acting on Reason / a. Practical reason
'Phronesis' should translate as 'practical intelligence', not as prudence [Annas]
     Full Idea: The best translation of 'phronesis' is probably not 'prudence' (which implies a non-moral motive), or 'practical wisdom' (which makes it sound contemplative), but 'practical intelligence', or just 'intelligence'.
     From: Julia Annas (The Morality of Happiness [1993], 2.3)
22. Metaethics / C. The Good / 3. Pleasure / d. Sources of pleasure
Epicureans achieve pleasure through character development [Annas]
     Full Idea: Since having a virtue does not reduce to performing certain kinds of acts, the Epicurean will achieve pleasure only by aiming at being a certain kind of person.
     From: Julia Annas (The Morality of Happiness [1993], 2.4)
     A reaction: No Epicurean would want to merely possess virtues, without enacting them. I assume that virtues are sought as guides to finding the finest pleasures (such as friendship).
23. Ethics / A. Egoism / 3. Cyrenaic School
Cyrenaics pursue pleasure, but don't equate it with happiness [Annas]
     Full Idea: Cyrenaics claimed our final good was pleasure, best achieved by seeking maximum intensity of pleasurable experiences, but they explicitly admitted that this was not happiness.
     From: Julia Annas (The Morality of Happiness [1993], 1)
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / c. Motivation for virtue
Ancient ethics uses attractive notions, not imperatives [Annas]
     Full Idea: Instead of modern 'imperative' notions of ethics (involving obligation, duty and rule-following), ancient ethics uses 'attractive' notions like those of goodness and worth
     From: Julia Annas (The Morality of Happiness [1993], Intro)
23. Ethics / D. Deontological Ethics / 1. Deontology
Principles cover life as a whole, where rules just cover actions [Annas]
     Full Idea: Principles concern not just types of actions, but one's life as a whole, grasping truths about the nature of justice, and the like; they explain rules, giving the 'why' and not just the 'what'.
     From: Julia Annas (The Morality of Happiness [1993], 2.4)
23. Ethics / D. Deontological Ethics / 2. Duty
Virtue theory tries to explain our duties in terms of our character [Annas]
     Full Idea: An ethics of virtue moves from an initial interest in what we ought to do to an interest in the kinds of people we are and hope to be, because the latter is taken to be the best way of understanding the former.
     From: Julia Annas (The Morality of Happiness [1993], 2.5)
23. Ethics / D. Deontological Ethics / 6. Motivation for Duty
If excessively good actions are admirable but not required, then duty isn't basic [Annas]
     Full Idea: Supererogatory actions are admirable and valuable, and we praise people for doing them, but they do not generate obligations to perform them, which casts doubt on obligation as the basic notion in ethics.
     From: Julia Annas (The Morality of Happiness [1993], 2.6)
23. Ethics / E. Utilitarianism / 1. Utilitarianism
We should do good when necessary, not maximise it [Annas]
     Full Idea: Why should I want to maximise my acting courageously? I act courageously when it is required.
     From: Julia Annas (The Morality of Happiness [1993], 1)
26. Natural Theory / C. Causation / 5. Direction of causation
A theory of causation should explain why cause precedes effect, not take it for granted [Lewis, by Field,H]
     Full Idea: Lewis thinks it is a major defect in a theory of causation that it builds in the condition that the time of the cause precede that of the effect: that cause precedes effect is something we ought to explain (which his counterfactual theory claims to do).
     From: report of David Lewis (Causation [1973]) by Hartry Field - Causation in a Physical World
     A reaction: My immediate reaction is that the chances of explaining such a thing are probably nil, and that we might as well just accept the direction of causation as a given. Even philosophers balk at the question 'why doesn't time go backwards?'
I reject making the direction of causation axiomatic, since that takes too much for granted [Lewis]
     Full Idea: One might stipulate that a cause must always precede its effect, but I reject this solution. It won't solve the problem of epiphenomena, it rejects a priori any backwards causation, and it trivializes defining time-direction through causation.
     From: David Lewis (Causation [1973], p.203)
     A reaction: [compressed] Not strong arguments, I would say. Maybe apparent causes are never epiphenomenal. Maybe backwards causation is impossible. Maybe we must use time to define causal direction, and not vice versa.
26. Natural Theory / C. Causation / 8. Particular Causation / d. Selecting the cause
It is just individious discrimination to pick out one cause and label it as 'the' cause [Lewis]
     Full Idea: We sometimes single out one among all the causes of some event and call it 'the' cause. ..We may select the abnormal causes, or those under human control, or those we deem good or bad, or those we want to talk about. This is invidious discrimination.
     From: David Lewis (Causation [1973])
     A reaction: This is the standard view expressed by Mill - presumably the obvious empiricist line. But if we specify 'the pre-conditions' for an event, we can't just mention ANY fact prior to the effect - there is obvious relevance. So why not for 'the' cause as well?
The modern regularity view says a cause is a member of a minimal set of sufficient conditions [Lewis]
     Full Idea: In present-day regularity analyses, a cause is defined (roughly) as any member of any minimal set of actual conditions that are jointly sufficient, given the laws, for the existence of the effect.
     From: David Lewis (Causation [1973], p.193)
     A reaction: This is the view Lewis is about to reject. It seem to summarise the essence of the Mackie INUS theory. This account would make the presence of oxygen a cause of almost every human event.
26. Natural Theory / C. Causation / 9. General Causation / a. Constant conjunction
Regularity analyses could make c an effect of e, or an epiphenomenon, or inefficacious, or pre-empted [Lewis]
     Full Idea: In the regularity analysis of causes, instead of c causing e, c might turn out to be an effect of e, or an epiphenomenon, or an inefficacious effect of a genuine cause, or a pre-empted cause (by some other cause) of e.
     From: David Lewis (Causation [1973], p.194)
     A reaction: These are Lewis's reasons for rejecting the general regularity account, in favour of his own particular counterfactual account. It is unlikely that c would be regularly pre-empted or epiphenomenal. If we build time's direction in, it won't be an effect.
26. Natural Theory / C. Causation / 9. General Causation / c. Counterfactual causation
The counterfactual view says causes are necessary (rather than sufficient) for their effects [Lewis, by Bird]
     Full Idea: The Humean idea, developed by Lewis, is that rather than being sufficient for their effects, causes are (counterfactual) necessary for their effects.
     From: report of David Lewis (Causation [1973]) by Alexander Bird - Causation and the Manifestation of Powers p.162
Lewis has basic causation, counterfactuals, and a general ancestral (thus handling pre-emption) [Lewis, by Bird]
     Full Idea: Lewis's basic account has a basic causal relation, counterfactual dependence, and the general causal relation is the ancestral of this basic one. ...This is motivated by counterfactual dependence failing to be general because of the pre-emption problem.
     From: report of David Lewis (Causation [1973]) by Alexander Bird - Causation and the Manifestation of Powers p.161
     A reaction: It is so nice when you struggle for ages with a topic, and then some clever person summarises it clearly for you.
Counterfactual causation implies all laws are causal, which they aren't [Tooley on Lewis]
     Full Idea: Some counterfactuals are based on non-causal laws, such as Newton's Third Law of Motion. 'If no force one way, then no force the other'. Lewis's counterfactual analysis implies that one force causes the other, which is not the case.
     From: comment on David Lewis (Causation [1973]) by Michael Tooley - Causation and Supervenience 5.2
     A reaction: So what exactly does 'cause' my punt to move forwards? Basing causal laws on counterfactual claims looks to me like putting the cart before the horse.
My counterfactual analysis applies to particular cases, not generalisations [Lewis]
     Full Idea: My (counterfactual) analysis is meant to apply to causation in particular cases; it is not an analysis of causal generalizations. Those presumably quantify over particulars, but it is hard to match natural language to the quantifiers.
     From: David Lewis (Causation [1973], p.195)
     A reaction: What authority could you have for asserting a counterfactual claim, if you only had one observation? Isn't the counterfactual claim the hallmark of a generalisation? For one case, 'if not-c, then not-e' is just a speculation.
One event causes another iff there is a causal chain from first to second [Lewis]
     Full Idea: One event is the cause of another iff there exists a causal chain leading from the first to the second.
     From: David Lewis (Causation [1973], p.200)
     A reaction: It will be necessary to both explain and identify a 'chain'. Some chains are extremely tenuous (Alexander could stop a barrel of beer). Go back a hundred years, and the cause of any present event is everything back then.
26. Natural Theory / D. Laws of Nature / 9. Counterfactual Claims
Lewis's account of counterfactuals is fine if we know what a law of nature is, but it won't explain the latter [Cohen,LJ on Lewis]
     Full Idea: Lewis can elucidate the logic of counterfactuals on the assumption that you are not at all puzzled about what a law of nature is. But if you are puzzled about this, it cannot contribute anything towards resolving your puzzlement.
     From: comment on David Lewis (Causation [1973]) by L. Jonathan Cohen - The Problem of Natural Laws p.219
     A reaction: This seems like a penetrating remark. The counterfactual theory is wrong, partly because it is epistemological instead of ontological, and partly because it refuses to face the really difficult problem, of what is going on out there.