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All the ideas for 'On the Question of Absolute Undecidability', 'Notebooks' and 'Probabilistic Causality'

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22 ideas

1. Philosophy / A. Wisdom / 3. Wisdom Deflated
Seek wisdom rather than truth; it is easier [Joubert]
     Full Idea: To seek wisdom rather than truth. It is more within our grasp.
     From: Joseph Joubert (Notebooks [1800], 1797)
     A reaction: A nice challenge to the traditional goal of philosophy. The idea that we should 'seek truth' only seems to have emerged during the Reformation. The Greeks may well never have dreamed of such a thing.
1. Philosophy / D. Nature of Philosophy / 1. Philosophy
We must think with our entire body and soul [Joubert]
     Full Idea: Everything we think must be thought with our entire being, body and soul.
     From: Joseph Joubert (Notebooks [1800], 1798)
     A reaction: Not just that thinking must be a whole-hearted activity, but that the very contents of our thinking will be better if it arises out of being a physical creature, and not just a disembodied reasoner. Maybe the bowels are not needed to analyse set theory.
1. Philosophy / E. Nature of Metaphysics / 2. Possibility of Metaphysics
The love of certainty holds us back in metaphysics [Joubert]
     Full Idea: What stops or holds us back in metaphysics is a love of certainty.
     From: Joseph Joubert (Notebooks [1800], 1814)
     A reaction: This is a prominent truth from the age of Descartes, but may have diminished in the twenty-first century. The very best metaphysicians (e.g. Aristotle and Lewis) always end in a trail of dots when things become unsure.
2. Reason / A. Nature of Reason / 9. Limits of Reason
The truths of reason instruct, but they do not illuminate [Joubert]
     Full Idea: There are truths that instruct, perhaps, but they do not illuminate. In this class are all the truths of reasoning.
     From: Joseph Joubert (Notebooks [1800], 1800)
     A reaction: A rather romantic view, which strikes me as false. An inspiring truth can suddenly collapse when you see why it must be false. Equally a line of reasoning can lead to a truth which need becomes an illumination.
3. Truth / A. Truth Problems / 1. Truth
Truth consists of having the same idea about something that God has [Joubert]
     Full Idea: Truth consists of having the same idea about something that God has.
     From: Joseph Joubert (Notebooks [1800], 1800)
     A reaction: Presumably sceptics about the existence of objective truth must also be sceptical about the possibility of such a God. I think Joubert is close to the nature of truth here. It is a remote and barely imaginable ideal.
4. Formal Logic / F. Set Theory ST / 1. Set Theory
Mathematical set theory has many plausible stopping points, such as finitism, and predicativism [Koellner]
     Full Idea: There are many coherent stopping points in the hierarchy of increasingly strong mathematical systems, starting with strict finitism, and moving up through predicativism to the higher reaches of set theory.
     From: Peter Koellner (On the Question of Absolute Undecidability [2006], Intro)
'Reflection principles' say the whole truth about sets can't be captured [Koellner]
     Full Idea: Roughly speaking, 'reflection principles' assert that anything true in V [the set hierarchy] falls short of characterising V in that it is true within some earlier level.
     From: Peter Koellner (On the Question of Absolute Undecidability [2006], 2.1)
5. Theory of Logic / K. Features of Logics / 5. Incompleteness
We have no argument to show a statement is absolutely undecidable [Koellner]
     Full Idea: There is at present no solid argument to the effect that a given statement is absolutely undecidable.
     From: Peter Koellner (On the Question of Absolute Undecidability [2006], 5.3)
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / i. Cardinal infinity
There are at least eleven types of large cardinal, of increasing logical strength [Koellner]
     Full Idea: Some of the standard large cardinals (in order of increasing (logical) strength) are: inaccessible, Mahlo, weakly compact, indescribable, Erdös, measurable, strong, Wodin, supercompact, huge etc. (...and ineffable).
     From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4)
     A reaction: [I don't understand how cardinals can have 'logical strength', but I pass it on anyway]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / d. Peano arithmetic
PA is consistent as far as we can accept, and we expand axioms to overcome limitations [Koellner]
     Full Idea: To the extent that we are justified in accepting Peano Arithmetic we are justified in accepting its consistency, and so we know how to expand the axiom system so as to overcome the limitation [of Gödel's Second Theorem].
     From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.1)
     A reaction: Each expansion brings a limitation, but then you can expand again.
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / g. Incompleteness of Arithmetic
Arithmetical undecidability is always settled at the next stage up [Koellner]
     Full Idea: The arithmetical instances of undecidability that arise at one stage of the hierarchy are settled at the next.
     From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4)
13. Knowledge Criteria / A. Justification Problems / 3. Internal or External / a. Pro-internalism
To know is to see inside oneself [Joubert]
     Full Idea: To know: it is to see inside oneself.
     From: Joseph Joubert (Notebooks [1800], 1800)
     A reaction: Extreme internalism about justification! Personally I am becoming convinced that 'know' (unlike 'believe' and 'true') is an entirely social concept. Fools spend a lot of time instrospecting; wise people ask around, and check in books.
15. Nature of Minds / C. Capacities of Minds / 2. Imagination
The imagination has made more discoveries than the eye [Joubert]
     Full Idea: The imagination has made more discoveries than the eye.
     From: Joseph Joubert (Notebooks [1800], 1797)
     A reaction: As a fan of the imagination, I love this one. I suspect that imagination, which was marginalised by Descartes, is actually the single most important aspect of thought (in slugs as well as humans). Abstraction requires imagination.
18. Thought / A. Modes of Thought / 1. Thought
A thought is as real as a cannon ball [Joubert]
     Full Idea: A thought is a thing as real as a cannon ball.
     From: Joseph Joubert (Notebooks [1800], 1801)
     A reaction: Nice. The realisation of a thought can strike someone as if they have been assaulted, and hearing some remarks can be as bad as being stabbed. That is quite apart from political consequences. Joubert is good on the physicality of thinking.
18. Thought / D. Concepts / 2. Origin of Concepts / c. Nativist concepts
Where does the bird's idea of a nest come from? [Joubert]
     Full Idea: The idea of the nest in the bird's mind, where does it come from?
     From: Joseph Joubert (Notebooks [1800], 1800)
     A reaction: I think this is a very striking example in support of innate ideas. Most animal behaviour can be explained as responses to stimuli, but the bird seems to hold a model in its mind while it collects its materials.
22. Metaethics / C. The Good / 3. Pleasure / b. Types of pleasure
He gives his body up to pleasure, but not his soul [Joubert]
     Full Idea: He gives his body up to pleasure, but not his soul.
     From: Joseph Joubert (Notebooks [1800], 1799)
     A reaction: A rather crucial distinction in the world of hedonism. There seems something sincere about someone who pursues pleasure body and soul, and something fractured about the pursuit of pleasure without real commitment. The split seems possible.
22. Metaethics / C. The Good / 3. Pleasure / c. Value of pleasure
What will you think of pleasures when you no longer enjoy them? [Joubert]
     Full Idea: What will you think of pleasures when you no longer enjoy them?
     From: Joseph Joubert (Notebooks [1800], 1802)
     A reaction: A lovely test question for aspiring young hedonists! It doesn't follow at all that we will despise past pleasures. The judgement may be utilitarian - that we regret the pleasures that harmed others, but love the harmless ones. Shame is social.
23. Ethics / C. Virtue Theory / 1. Virtue Theory / b. Basis of virtue
Virtue is hard if we are scorned; we need support [Joubert]
     Full Idea: It would be difficult to be scorned and to live virtuously. We have need of support.
     From: Joseph Joubert (Notebooks [1800], 1800)
     A reaction: He seems to have hit on what I take to be one of the keys to Aristotle: that virtue is a social matter, requiring both upbringing and a healthy culture. But we can help to create that culture, as well as benefiting from it.
25. Social Practice / E. Policies / 5. Education / a. Aims of education
In raising a child we must think of his old age [Joubert]
     Full Idea: In raising a child we must think of his old age.
     From: Joseph Joubert (Notebooks [1800], 1809)
     A reaction: Very nice, and Aristotle would approve. If educators think much about the future, it rarely extends before the child's first job. We should be preparing good grand-parents, as well as parents and employees. Educate for retirement!
26. Natural Theory / C. Causation / 8. Particular Causation / e. Probabilistic causation
Probabilistic causal concepts are widely used in everyday life and in science [Salmon]
     Full Idea: Probabilistic causal concepts are used in innumerable contexts of everyday life and science. ...In causes of cancer, road accidents, or food poisoning, for example.
     From: Wesley Salmon (Probabilistic Causality [1980], p.137)
     A reaction: [Second half compresses his examples] This strikes me as rather a weak point. No one ever thought that a particular road accident was actually caused by the high probability of it at a particular location. Causes are in the mechanisms.
28. God / A. Divine Nature / 6. Divine Morality / c. God is the good
We can't exactly conceive virtue without the idea of God [Joubert]
     Full Idea: If we exclude the idea of God, it is impossible to have an exact idea of virtue.
     From: Joseph Joubert (Notebooks [1800], 1808)
     A reaction: I suspect that an 'exact' idea is impossible even with an idea of God. This is an interesting defence of the importance of God in moral thinking, but it only requires the concept of a supreme being, and not belief.
29. Religion / B. Monotheistic Religion / 4. Christianity / a. Christianity
We cannot speak against Christianity without anger, or speak for it without love [Joubert]
     Full Idea: We cannot speak against Christianity without anger, or speak for it without love.
     From: Joseph Joubert (Notebooks [1800], 1801)
     A reaction: This seems to be rather true at the present time, when a wave of anti-religious books is sweeping through our culture. Presumably this remark used to be true of ancient paganism, but it died away. Christianity, though, is very personal.