Combining Texts

All the ideas for 'The Laws', 'On Second-Order Logic' and 'Thinking About Mathematics'

expand these ideas     |    start again     |     specify just one area for these texts


67 ideas

1. Philosophy / D. Nature of Philosophy / 5. Aims of Philosophy / e. Philosophy as reason
We shouldn't always follow where the argument leads! [Lewis on Plato]
2. Reason / A. Nature of Reason / 1. On Reason
It is foolish to quarrel with the mind's own reasoning processes [Plato]
2. Reason / A. Nature of Reason / 4. Aims of Reason
We ought to follow where the argument leads us [Plato]
2. Reason / A. Nature of Reason / 9. Limits of Reason
Mortals are incapable of being fully rational [Plato]
3. Truth / A. Truth Problems / 3. Value of Truth
Truth has the supreme value, for both gods and men [Plato]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
Boolos reinterprets second-order logic as plural logic [Boolos, by Oliver/Smiley]
Second-order logic metatheory is set-theoretic, and second-order validity has set-theoretic problems [Boolos]
5. Theory of Logic / C. Ontology of Logic / 1. Ontology of Logic
A sentence can't be a truth of logic if it asserts the existence of certain sets [Boolos]
5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle
Intuitionists deny excluded middle, because it is committed to transcendent truth or objects [Shapiro]
5. Theory of Logic / G. Quantification / 2. Domain of Quantification
'∀x x=x' only means 'everything is identical to itself' if the range of 'everything' is fixed [Boolos]
5. Theory of Logic / K. Features of Logics / 4. Completeness
Weak completeness: if it is valid, it is provable. Strong: it is provable from a set of sentences [Boolos]
5. Theory of Logic / K. Features of Logics / 6. Compactness
Why should compactness be definitive of logic? [Boolos, by Hacking]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / b. Types of number
The number 3 is presumably identical as a natural, an integer, a rational, a real, and complex [Shapiro]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / h. Reals from Cauchy
Cauchy gave a formal definition of a converging sequence. [Shapiro]
6. Mathematics / B. Foundations for Mathematics / 1. Foundations for Mathematics
Categories are the best foundation for mathematics [Shapiro]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / e. Peano arithmetic 2nd-order
Many concepts can only be expressed by second-order logic [Boolos]
6. Mathematics / B. Foundations for Mathematics / 5. Definitions of Number / f. Zermelo numbers
Two definitions of 3 in terms of sets disagree over whether 1 is a member of 3 [Shapiro]
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / a. Structuralism
Numbers do not exist independently; the essence of a number is its relations to other numbers [Shapiro]
A 'system' is related objects; a 'pattern' or 'structure' abstracts the pure relations from them [Shapiro]
6. Mathematics / C. Sources of Mathematics / 6. Logicism / d. Logicism critique
Logicism seems to be a non-starter if (as is widely held) logic has no ontology of its own [Shapiro]
6. Mathematics / C. Sources of Mathematics / 7. Formalism
Term Formalism says mathematics is just about symbols - but real numbers have no names [Shapiro]
Game Formalism is just a matter of rules, like chess - but then why is it useful in science? [Shapiro]
Deductivism says mathematics is logical consequences of uninterpreted axioms [Shapiro]
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / b. Intuitionism
Critics resent the way intuitionism cripples mathematics, but it allows new important distinctions [Shapiro]
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / c. Conceptualism
Conceptualist are just realists or idealist or nominalists, depending on their view of concepts [Shapiro]
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / d. Predicativism
'Impredicative' definitions refer to the thing being described [Shapiro]
9. Objects / D. Essence of Objects / 4. Essence as Definition
To grasp a thing we need its name, its definition, and what it really is [Plato]
12. Knowledge Sources / C. Rationalism / 1. Rationalism
Rationalism tries to apply mathematical methodology to all of knowledge [Shapiro]
15. Nature of Minds / A. Nature of Mind / 2. Psuche
Soul is what is defined by 'self-generating motion' [Plato]
16. Persons / B. Nature of the Self / 3. Self as Non-physical
My individuality is my soul, which carries my body around [Plato]
21. Aesthetics / A. Aesthetic Experience / 4. Beauty
People who value beauty above virtue insult the soul by placing the body above it [Plato]
22. Metaethics / C. The Good / 1. Goodness / g. Consequentialism
An action is only just if it is performed by someone with a just character and outlook [Plato]
22. Metaethics / C. The Good / 1. Goodness / i. Moral luck
Attempted murder is like real murder, but we should respect the luck which avoided total ruin [Plato]
22. Metaethics / C. The Good / 3. Pleasure / c. Value of pleasure
It would be strange if the gods rewarded those who experienced the most pleasure in life [Plato]
22. Metaethics / C. The Good / 3. Pleasure / f. Dangers of pleasure
The conquest of pleasure is the noblest victory of all [Plato]
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / c. Motivation for virtue
Every crime is the result of excessive self-love [Plato]
The only worthwhile life is one devoted to physical and moral perfection [Plato]
Virtue is a concord of reason and emotion, with pleasure and pain trained to correct ends [Plato]
A serious desire for moral excellence is very rare indeed [Plato]
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / d. Teaching virtue
Virtue is the aim of all laws [Plato]
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / j. Unity of virtue
The Guardians must aim to discover the common element in the four cardinal virtues [Plato]
23. Ethics / C. Virtue Theory / 3. Virtues / b. Temperance
Excessive laughter and tears must be avoided [Plato]
23. Ethics / C. Virtue Theory / 3. Virtues / c. Justice
Injustice is the mastery of the soul by bad feelings, even if they do not lead to harm [Plato]
23. Ethics / C. Virtue Theory / 4. External Goods / c. Wealth
Virtue and great wealth are incompatible [Plato]
The best people are produced where there is no excess of wealth or poverty [Plato]
24. Political Theory / C. Ruling a State / 2. Leaders / c. Despotism
Totalitarian states destroy friendships and community spirit [Plato]
24. Political Theory / D. Ideologies / 7. Communitarianism / a. Communitarianism
Education in virtue produces citizens who are active but obedient [Plato]
25. Social Practice / B. Equalities / 1. Grounds of equality
Men and women should qualify equally for honours on merit [Plato]
Friendship is impossible between master and slave, even if they are made equal [Plato]
25. Social Practice / C. Rights / 1. Basis of Rights
Sound laws achieve the happiness of those who observe them [Plato]
25. Social Practice / D. Justice / 1. Basis of justice
Justice is granting the equality which unequals deserve [Plato]
25. Social Practice / E. Policies / 5. Education / b. Education principles
Mathematics has the widest application of any subject on the curriculum [Plato]
Children's games should channel their pleasures into adult activity [Plato]
Control of education is the key office of state, and should go to the best citizen [Plato]
25. Social Practice / E. Policies / 5. Education / c. Teaching
Education is channelling a child's feelings into the right course before it understands why [Plato]
The best way to educate the young is not to rebuke them, but to set a good example [Plato]
26. Natural Theory / A. Speculations on Nature / 2. Natural Purpose / a. Final purpose
Creation is not for you; you exist for the sake of creation [Plato]
27. Natural Reality / E. Cosmology / 3. The Beginning
Movement is transmitted through everything, and it must have started with self-generated motion [Plato]
28. God / A. Divine Nature / 6. Divine Morality / d. God decrees morality
In 'The Laws', to obey the law is to be obey god [Plato, by MacIntyre]
28. God / B. Proving God / 3. Proofs of Evidence / a. Cosmological Proof
Self-generating motion is clearly superior to all other kinds of motion [Plato]
The only possible beginning for the endless motions of reality is something self-generated [Plato]
Self-moving soul has to be the oldest thing there is [Plato]
28. God / B. Proving God / 3. Proofs of Evidence / b. Teleological Proof
Soul must be the cause of all the opposites, such as good and evil or beauty and ugliness [Plato]
If all the motions of nature reflect calculations of reason, then the best kind of soul must direct it [Plato]
28. God / C. Attitudes to God / 5. Atheism
If astronomical movements are seen as necessary instead of by divine will, this leads to atheism [Plato]
29. Religion / A. Polytheistic Religion / 1. Animism
The heavens must be full of gods, controlling nature either externally or from within [Plato]
29. Religion / A. Polytheistic Religion / 4. Dualist Religion
There must be at least two souls controlling the cosmos, one doing good, the other the opposite [Plato]