13 ideas
| 10153 | In everyday language, truth seems indefinable, inconsistent, and illogical [Tarski] |
| Full Idea: In everyday language it seems impossible to define the notion of truth or even to use this notion in a consistent manner and in agreement with the laws of logic. | |
| From: Alfred Tarski (works [1936]), quoted by Feferman / Feferman - Alfred Tarski: life and logic Int III | |
| A reaction: [1935] See Logic|Theory of Logic|Semantics of Logic for Tarski's approach to truth. |
| 19141 | Tarski thought axiomatic truth was too contingent, and in danger of inconsistencies [Tarski, by Davidson] |
| Full Idea: Tarski preferred an explicit definition of truth to axioms. He says axioms have a rather accidental character, only a definition can guarantee the continued consistency of the system, and it keeps truth in harmony with physical science and physicalism. | |
| From: report of Alfred Tarski (works [1936]) by Donald Davidson - Truth and Predication 2 n2 | |
| A reaction: Davidson's summary, gleaned from various sources in Tarski. A big challenge for modern axiom systems is to avoid inconsistency, which is extremely hard to do (given that set theory is not sure of having achieved it). |
| 10048 | There is no clear boundary between the logical and the non-logical [Tarski] |
| Full Idea: No objective grounds are known to me which permit us to draw a sharp boundary between the two groups of terms, the logical and the non-logical. | |
| From: Alfred Tarski (works [1936]), quoted by Alan Musgrave - Logicism Revisited §3 | |
| A reaction: Musgrave is pointing out that this is bad news if you want to 'reduce' something like arithmetic to logic. 'Logic' is a vague object. |
| 10479 | Logical consequence: true premises give true conclusions under all interpretations [Tarski, by Hodges,W] |
| Full Idea: Tarski's definition of logical consequence (1936) is that in a fully interpreted formal language an argument is valid iff under any allowed interpretation of its nonlogical symbols, if the premises are true then so is the conclusion. | |
| From: report of Alfred Tarski (works [1936]) by Wilfrid Hodges - Model Theory 3 | |
| A reaction: The idea that you can only make these claims 'under an interpretation' seems to have had a huge influence on later philosophical thinking. |
| 10694 | Logical consequence is when in any model in which the premises are true, the conclusion is true [Tarski, by Beall/Restall] |
| Full Idea: Tarski's 1936 definition of logical consequence is that in any model in which the premises are true, the conclusion is true too (so that no model can make the conclusion false). | |
| From: report of Alfred Tarski (works [1936]) by JC Beall / G Restall - Logical Consequence 3 | |
| A reaction: So the general idea is that a logical consequence is distinguished by being unstoppable. Sounds good. But then we have monotonic and non-monotonic logics, which (I'm guessing) embody different notions of consequence. |
| 10157 | Tarski improved Hilbert's geometry axioms, and without set-theory [Tarski, by Feferman/Feferman] |
| Full Idea: Tarski found an elegant new axiom system for Euclidean geometry that improved Hilbert's earlier version - and he formulated it without the use of set-theoretical notions. | |
| From: report of Alfred Tarski (works [1936]) by Feferman / Feferman - Alfred Tarski: life and logic Ch.9 |
| 20180 | A happy and joyous life must largely be a quiet life [Russell] |
| Full Idea: A happy life must to a great extent be a quiet life, for it is only in an atmosphere of quiet that true joy can live. | |
| From: Bertrand Russell (The Conquest of Happiness [1930], 4) | |
| A reaction: Most people's image of happiness is absorption in an interesting task, or relaxing in good company. The idea that happiness is wild excitement exists, but is a minority view. |
| 20177 | Boredom always involves not being fully occupied [Russell] |
| Full Idea: It is one of the essentials of boredom that one's faculties must not be fully occupied. | |
| From: Bertrand Russell (The Conquest of Happiness [1930], 4) | |
| A reaction: He gives running for your life as an example of non-boredom. I suspect that this is only the sort of boredom that troubled Russell, and not the sort of profound boredom that led the actor George Sanders to suicide (according to his last note). |
| 20178 | Life is now more interesting, but boredom is more frightening [Russell] |
| Full Idea: We are less bored than our ancestors were, but we are more afraid of boredom | |
| From: Bertrand Russell (The Conquest of Happiness [1930], 4) | |
| A reaction: I get the impression that the invention of the powerful mobile phone has largely banished boredom from human life, except when you are obliged to switch it off. The fear of boredom may hence be even greater now. |
| 20176 | Boredom is an increasingly strong motivating power [Russell] |
| Full Idea: Boredom has been, I believe, one of the great motive powers throughout the historical epoch, and is so at the present day more than ever. | |
| From: Bertrand Russell (The Conquest of Happiness [1930], 4) | |
| A reaction: Most of his essay tells us how to avoid boredom, rather than how it motivates. |
| 20179 | Happiness involves enduring boredom, and the young should be taught this [Russell] |
| Full Idea: A certain power of enduring boredom is essential to a happy life, and is one of the things that ought to be taught to the young. | |
| From: Bertrand Russell (The Conquest of Happiness [1930], 4) | |
| A reaction: As an example he suggests that Wordsworth would never have written 'The Prelude' is he had never been bored when young. Which suggests that Russell doesn't really get boredom, seeing it merely as a stimulus to work. |
| 1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
| Full Idea: Archelaus was the first person to say that the universe is boundless. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 02.Ar.3 |
| 5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |
| Full Idea: Archelaus wrote that life on Earth began in a primeval slime. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Malcolm Schofield - Archelaus | |
| A reaction: This sounds like a fairly clearcut assertion of the production of life by evolution. Darwin's contribution was to propose the mechanism for achieving it. We should honour the name of Archelaus for this idea. |