Combining Texts

All the ideas for 'Beginning Logic', 'Problems in Personal Identity' and 'The Metaphysics within Physics'

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


84 ideas

1. Philosophy / E. Nature of Metaphysics / 4. Metaphysics as Science
The metaphysics of nature should focus on physics [Maudlin]
1. Philosophy / E. Nature of Metaphysics / 6. Metaphysics as Conceptual
Kant survives in seeing metaphysics as analysing our conceptual system, which is a priori [Maudlin]
1. Philosophy / E. Nature of Metaphysics / 7. Against Metaphysics
Wide metaphysical possibility may reduce metaphysics to analysis of fantasies [Maudlin]
2. Reason / B. Laws of Thought / 6. Ockham's Razor
If the universe is profligate, the Razor leads us astray [Maudlin]
The Razor rightly prefers one cause of multiple events to coincidences of causes [Maudlin]
4. Formal Logic / B. Propositional Logic PL / 1. Propositional Logic
'Contradictory' propositions always differ in truth-value [Lemmon]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / a. Symbols of PL
We write the conditional 'if P (antecedent) then Q (consequent)' as P→Q [Lemmon]
That proposition that either P or Q is their 'disjunction', written P∨Q [Lemmon]
That proposition that both P and Q is their 'conjunction', written P∧Q [Lemmon]
We write the 'negation' of P (not-P) as ¬ [Lemmon]
We write 'P if and only if Q' as P↔Q; it is also P iff Q, or (P→Q)∧(Q→P) [Lemmon]
If A and B are 'interderivable' from one another we may write A -||- B [Lemmon]
The sign |- may be read as 'therefore' [Lemmon]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / b. Terminology of PL
A 'well-formed formula' follows the rules for variables, ¬, →, ∧, ∨, and ↔ [Lemmon]
The 'scope' of a connective is the connective, the linked formulae, and the brackets [Lemmon]
A 'substitution-instance' is a wff formed by consistent replacing variables with wffs [Lemmon]
A wff is 'inconsistent' if all assignments to variables result in the value F [Lemmon]
'Contrary' propositions are never both true, so that ¬(A∧B) is a tautology [Lemmon]
Two propositions are 'equivalent' if they mirror one another's truth-value [Lemmon]
A wff is 'contingent' if produces at least one T and at least one F [Lemmon]
'Subcontrary' propositions are never both false, so that A∨B is a tautology [Lemmon]
A 'implies' B if B is true whenever A is true (so that A→B is tautologous) [Lemmon]
A wff is a 'tautology' if all assignments to variables result in the value T [Lemmon]
A 'theorem' is the conclusion of a provable sequent with zero assumptions [Lemmon]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / c. Derivation rules of PL
∧I: Given A and B, we may derive A∧B [Lemmon]
CP: Given a proof of B from A as assumption, we may derive A→B [Lemmon]
MPP: Given A and A→B, we may derive B [Lemmon]
∨E: Derive C from A∨B, if C can be derived both from A and from B [Lemmon]
DN: Given A, we may derive ¬¬A [Lemmon]
A: we may assume any proposition at any stage [Lemmon]
∧E: Given A∧B, we may derive either A or B separately [Lemmon]
RAA: If assuming A will prove B∧¬B, then derive ¬A [Lemmon]
MTT: Given ¬B and A→B, we derive ¬A [Lemmon]
∨I: Given either A or B separately, we may derive A∨B [Lemmon]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / d. Basic theorems of PL
'Modus tollendo ponens' (MTP) says ¬P, P ∨ Q |- Q [Lemmon]
'Modus ponendo tollens' (MPT) says P, ¬(P ∧ Q) |- ¬Q [Lemmon]
We can change conditionals into negated conjunctions with P→Q -||- ¬(P ∧ ¬Q) [Lemmon]
We can change conditionals into disjunctions with P→Q -||- ¬P ∨ Q [Lemmon]
De Morgan's Laws make negated conjunctions/disjunctions into non-negated disjunctions/conjunctions [Lemmon]
The Distributive Laws can rearrange a pair of conjunctions or disjunctions [Lemmon]
We can change conjunctions into negated conditionals with P→Q -||- ¬(P → ¬Q) [Lemmon]
4. Formal Logic / B. Propositional Logic PL / 3. Truth Tables
Truth-tables are good for showing invalidity [Lemmon]
A truth-table test is entirely mechanical, but this won't work for more complex logic [Lemmon]
4. Formal Logic / B. Propositional Logic PL / 4. Soundness of PL
If any of the nine rules of propositional logic are applied to tautologies, the result is a tautology [Lemmon]
4. Formal Logic / B. Propositional Logic PL / 5. Completeness of PL
Propositional logic is complete, since all of its tautologous sequents are derivable [Lemmon]
4. Formal Logic / C. Predicate Calculus PC / 2. Tools of Predicate Calculus / a. Symbols of PC
Write '(∀x)(...)' to mean 'take any x: then...', and '(∃x)(...)' to mean 'there is an x such that....' [Lemmon]
'Gm' says m has property G, and 'Pmn' says m has relation P to n [Lemmon]
The 'symbols' are bracket, connective, term, variable, predicate letter, reverse-E [Lemmon]
4. Formal Logic / C. Predicate Calculus PC / 2. Tools of Predicate Calculus / b. Terminology of PC
Our notation uses 'predicate-letters' (for 'properties'), 'variables', 'proper names', 'connectives' and 'quantifiers' [Lemmon]
4. Formal Logic / C. Predicate Calculus PC / 2. Tools of Predicate Calculus / c. Derivations rules of PC
Universal Elimination (UE) lets us infer that an object has F, from all things having F [Lemmon]
With finite named objects, we can generalise with &-Intro, but otherwise we need ∀-Intro [Lemmon]
UE all-to-one; UI one-to-all; EI arbitrary-to-one; EE proof-to-one [Lemmon]
Predicate logic uses propositional connectives and variables, plus new introduction and elimination rules [Lemmon]
Universal elimination if you start with the universal, introduction if you want to end with it [Lemmon]
4. Formal Logic / C. Predicate Calculus PC / 2. Tools of Predicate Calculus / d. Universal quantifier ∀
If there is a finite domain and all objects have names, complex conjunctions can replace universal quantifiers [Lemmon]
4. Formal Logic / C. Predicate Calculus PC / 2. Tools of Predicate Calculus / e. Existential quantifier ∃
'Some Frenchmen are generous' is rendered by (∃x)(Fx→Gx), and not with the conditional → [Lemmon]
5. Theory of Logic / B. Logical Consequence / 8. Material Implication
The paradoxes of material implication are P |- Q → P, and ¬P |- P → Q [Lemmon]
5. Theory of Logic / D. Assumptions for Logic / 4. Identity in Logic
In logic identity involves reflexivity (x=x), symmetry (if x=y, then y=x) and transitivity (if x=y and y=z, then x=z) [Baillie]
7. Existence / C. Structure of Existence / 5. Supervenience / d. Humean supervenience
The Humean view is wrong; laws and direction of time are primitive, and atoms are decided by physics [Maudlin]
Lewis says it supervenes on the Mosaic, but actually thinks the Mosaic is all there is [Maudlin]
If the Humean Mosaic is ontological bedrock, there can be no explanation of its structure [Maudlin]
The 'spinning disc' is just impossible, because there cannot be 'homogeneous matter' [Maudlin]
7. Existence / D. Theories of Reality / 11. Ontological Commitment / d. Commitment of theories
To get an ontology from ontological commitment, just add that some theory is actually true [Maudlin]
7. Existence / D. Theories of Reality / 11. Ontological Commitment / e. Ontological commitment problems
Naïve translation from natural to formal language can hide or multiply the ontology [Maudlin]
8. Modes of Existence / B. Properties / 5. Natural Properties
A property is fundamental if two objects can differ in only that respect [Maudlin]
8. Modes of Existence / B. Properties / 12. Denial of Properties
Fundamental physics seems to suggest there are no such things as properties [Maudlin]
8. Modes of Existence / D. Universals / 2. Need for Universals
Existence of universals may just be decided by acceptance, or not, of second-order logic [Maudlin]
10. Modality / A. Necessity / 5. Metaphysical Necessity
Logically impossible is metaphysically impossible, but logically possible is not metaphysically possible [Maudlin]
10. Modality / B. Possibility / 9. Counterfactuals
A counterfactual antecedent commands the redescription of a selected moment [Maudlin]
14. Science / C. Induction / 1. Induction
Induction leaps into the unknown, but usually lands safely [Maudlin]
14. Science / D. Explanation / 2. Types of Explanation / e. Lawlike explanations
Laws should help explain the things they govern, or that manifest them [Maudlin]
26. Natural Theory / C. Causation / 9. General Causation / c. Counterfactual causation
Evaluating counterfactuals involves context and interests [Maudlin]
We don't pick a similar world from many - we construct one possibility from the description [Maudlin]
The counterfactual is ruined if some other cause steps in when the antecedent fails [Maudlin]
If we know the cause of an event, we seem to assent to the counterfactual [Maudlin]
If the effect hadn't occurred the cause wouldn't have happened, so counterfactuals are two-way [Maudlin]
26. Natural Theory / D. Laws of Nature / 1. Laws of Nature
Laws are primitive, so two indiscernible worlds could have the same laws [Maudlin]
Fundamental laws say how nature will, or might, evolve from some initial state [Maudlin]
Laws of nature are ontological bedrock, and beyond analysis [Maudlin]
26. Natural Theory / D. Laws of Nature / 4. Regularities / a. Regularity theory
'Humans with prime house numbers are mortal' is not a law, because not a natural kind [Maudlin]
26. Natural Theory / D. Laws of Nature / 4. Regularities / b. Best system theory
If laws are just regularities, then there have to be laws [Maudlin]
27. Natural Reality / D. Time / 1. Nature of Time / a. Absolute time
I believe the passing of time is a fundamental fact about the world [Maudlin]
27. Natural Reality / D. Time / 2. Passage of Time / b. Rate of time
If time passes, presumably it passes at one second per second [Maudlin]
27. Natural Reality / D. Time / 2. Passage of Time / e. Tensed (A) series
There is one ordered B series, but an infinitude of A series, depending on when the present is [Maudlin]