21 ideas
| 18365 | If truths are just identical with facts, then truths will make themselves true [David] |
| Full Idea: According to the identity theory of truth, a proposition is true if and only if it is identical with a fact. ...This leads to the unacceptable claim that every true proposition makes itself true (because it is identical to its fact). | |
| From: Marian David (Truth-making and Correspondence [2009], n 14) |
| 18362 | Examples show that truth-making is just non-symmetric, not asymmetric [David] |
| Full Idea: That 'there is at least one proposition' ...is a case where something makes itself true, which generates a counterexample to the natural assumption that truth-making is asymmetric; truth-making, it seems, is merely non-symmetric. | |
| From: Marian David (Truth-making and Correspondence [2009], 4) |
| 18360 | It is assumed that a proposition is necessarily true if its truth-maker exists [David] |
| Full Idea: Friends of the truth-maker principle usually hold that the following states a crucial necessary condition on truth-making: if x makes y true, then, necessarily, if x exists then y is true. | |
| From: Marian David (Truth-making and Correspondence [2009], 2) | |
| A reaction: My objection is that the proposition y is taken to pre-exist, primly awaiting the facts that will award it 'truth'. An ontology that contains an infinity of propositions, most of which so far lack a truth-value, is incoherent. You can have x, but no y! |
| 18358 | Two different propositions can have the same fact as truth-maker [David] |
| Full Idea: Two different propositions can have the same fact as truth-maker. For example, 'L is happy or L is hungry', and 'L is happy or L is thirsty', which are both made true by the fact that L is happy. | |
| From: Marian David (Truth-making and Correspondence [2009], 1) |
| 18355 | What matters is truth-making (not truth-makers) [David] |
| Full Idea: The term 'truthmaker' just labels whatever stands in the truth-making relation to a truth. The truth-making relation is crucial. It would have been just as well to refer to the truth-'maker' principle as the truth-'making' principle. | |
| From: Marian David (Truth-making and Correspondence [2009], 1) | |
| A reaction: This is well said. The commitment of this theory is to something which makes each proposition true. There is no initial commitment to any theories about what sorts of things do the job. |
| 18354 | Correspondence is symmetric, while truth-making is taken to be asymmetric [David] |
| Full Idea: Correspondence appears to be a symmetric relation while truth-making appears to be, or is supposed to be, an asymmetric relation. | |
| From: Marian David (Truth-making and Correspondence [2009], Intro) |
| 18356 | Correspondence is an over-ambitious attempt to explain truth-making [David] |
| Full Idea: Truth-maker theory says that the attempt by correspondence to fill in the generic truth-maker principle with something more informative fails. It is too ambitious, offering a whole zoo of funny facts that are not needed. | |
| From: Marian David (Truth-making and Correspondence [2009], 1) | |
| A reaction: A typical funny fact is a disjunctive fact, which makes 'he is hungry or thirsty' true (when it can just be made true by the simple fact that he is thirsty). |
| 18363 | Correspondence theorists see facts as the only truth-makers [David] |
| Full Idea: Correspondence theorists are committed to the view that, since truth is correspondence with a fact, only facts can make true propositions true. | |
| From: Marian David (Truth-making and Correspondence [2009], 4) |
| 18364 | Correspondence theory likes ideal languages, that reveal the structure of propositions [David] |
| Full Idea: Correspondence theorists tend to promote ideal languages, ...which is intended to mirror perfectly the structure of the propositions it expresses. | |
| From: Marian David (Truth-making and Correspondence [2009], n 03) |
| 18357 | What makes a disjunction true is simpler than the disjunctive fact it names [David] |
| Full Idea: The proposition that 'L is happy or hungry' can be made true by the fact that L is happy. This does not have the same complexity or constituent structure as the proposition it makes true. | |
| From: Marian David (Truth-making and Correspondence [2009], 1) |
| 18359 | One proposition can be made true by many different facts [David] |
| Full Idea: One proposition can be made true by many different facts (such as 'there are some happy dogs'). | |
| From: Marian David (Truth-making and Correspondence [2009], 1) |
| 13913 | The four 'perfect syllogisms' are called Barbara, Celarent, Darii and Ferio [Engelbretsen/Sayward] |
| Full Idea: There are four 'perfect syllogisms': Barbara (every M is P, every S is M, so every S is P); Celarent (no M is P, every S is M, so no S is P); Darii (every M is P, some S is M, so some S is P); Ferio (no M is P, some S is M, so some S is not P). | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8) | |
| A reaction: The four names are mnemonics from medieval universities. |
| 13914 | Syllogistic logic has one rule: what is affirmed/denied of wholes is affirmed/denied of their parts [Engelbretsen/Sayward] |
| Full Idea: It has often been claimed (e.g. by Leibniz) that a single rule governs all syllogistic validity, called 'dictum de omni et null', which says that what is affirmed or denied of any whole is affirmed or denied of any part of that whole. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8) | |
| A reaction: This seems to be the rule which is captured by Venn Diagrams. |
| 13915 | Syllogistic can't handle sentences with singular terms, or relational terms, or compound sentences [Engelbretsen/Sayward] |
| Full Idea: Three common kinds of sentence cannot be put into syllogistic ('categorical') form: ones using singular terms ('Mars is red'), ones using relational terms ('every painter owns some brushes'), and compound sentences. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8) |
| 13916 | Term logic uses expression letters and brackets, and '-' for negative terms, and '+' for compound terms [Engelbretsen/Sayward] |
| Full Idea: Term logic begins with expressions and two 'term functors'. Any simple letter is a 'term', any term prefixed by a minus ('-') is a 'negative term', and any pair of terms flanking a plus ('+') is a 'compound term'. Parenthese are used for grouping. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 8) | |
| A reaction: [see Engelbretsen and Sayward for the full formal system] |
| 13850 | In modern logic all formal validity can be characterised syntactically [Engelbretsen/Sayward] |
| Full Idea: One of the key ideas of modern formal logic is that all formally valid inferences can be specified in strictly syntactic terms. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], Ch.2) |
| 13849 | Classical logic rests on truth and models, where constructivist logic rests on defence and refutation [Engelbretsen/Sayward] |
| Full Idea: Classical logic rests on the concepts of truth and falsity (and usually makes use of a semantic theory based on models), whereas constructivist logic accounts for inference in terms of defense and refutation. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], Intro) | |
| A reaction: My instincts go with the classical view, which is that inferences do not depend on the human capacity to defend them, but sit there awaiting revelation. My view isn't platonist, because I take the inferences to be rooted in the physical world. |
| 13851 | Unlike most other signs, = cannot be eliminated [Engelbretsen/Sayward] |
| Full Idea: Unlike ∨, →, ↔, and ∀, the sign = is not eliminable from a logic. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], Ch.3) |
| 13852 | Axioms are ω-incomplete if the instances are all derivable, but the universal quantification isn't [Engelbretsen/Sayward] |
| Full Idea: A set of axioms is said to be ω-incomplete if, for some universal quantification, each of its instances is derivable from those axioms but the quantification is not thus derivable. | |
| From: Engelbretsen,G/Sayward,C (Philosophical Logic: Intro to Advanced Topics [2011], 7) |
| 18361 | A reflexive relation entails that the relation can't be asymmetric [David] |
| Full Idea: An asymmetric relation must be irreflexive: any case of aRa will yield a reductio of the assumption that R is asymmetric. | |
| From: Marian David (Truth-making and Correspondence [2009], 4) |
| 1513 | The Egyptians were the first to say the soul is immortal and reincarnated [Herodotus] |
| Full Idea: The Egyptians were the first to claim that the soul of a human being is immortal, and that each time the body dies the soul enters another creature just as it is being born. | |
| From: Herodotus (The Histories [c.435 BCE], 2.123.2) |