22 ideas
| 9271 | Human knowledge may not produce well-being; the examined life may not be worth living [Gray] |
| Full Idea: Human knowledge is one thing, human well-being another. There is no predetermined harmony between the two. The examined life may not be worth living. | |
| From: John Gray (Straw Dogs [2002], 1.9) | |
| A reaction: John Gray has set himself up as the Eeyore of modern times, but this point may obviously be correct. Presumably Socrates meant that the examined life was better even if the result was less 'well-being'. Even Gray doesn't want a lobotomy. |
| 11022 | Gentzen introduced a natural deduction calculus (NK) in 1934 [Gentzen, by Read] |
| Full Idea: Gentzen introduced a natural deduction calculus (NK) in 1934. | |
| From: report of Gerhard Gentzen (works [1938]) by Stephen Read - Thinking About Logic Ch.8 |
| 11065 | The inferential role of a logical constant constitutes its meaning [Gentzen, by Hanna] |
| Full Idea: Gentzen argued that the inferential role of a logical constant constitutes its meaning. | |
| From: report of Gerhard Gentzen (works [1938]) by Robert Hanna - Rationality and Logic 5.3 | |
| A reaction: Possibly inspired by Wittgenstein's theory of meaning as use? This idea was the target of Prior's famous connective 'tonk', which has the role of implying anything you like, proving sentences which are not logical consequences. |
| 11023 | The logical connectives are 'defined' by their introduction rules [Gentzen] |
| Full Idea: The introduction rules represent, as it were, the 'definitions' of the symbols concerned, and the elimination rules are no more, in the final analysis, than the consequences of these definitions. | |
| From: Gerhard Gentzen (works [1938]), quoted by Stephen Read - Thinking About Logic Ch.8 | |
| A reaction: If an introduction-rule (or a truth table) were taken as fixed and beyond dispute, then it would have the status of a definition, since there would be nothing else to appeal to. So is there anything else to appeal to here? |
| 11213 | Each logical symbol has an 'introduction' rule to define it, and hence an 'elimination' rule [Gentzen] |
| Full Idea: To every logical symbol there belongs precisely one inference figure which 'introduces' the symbol ..and one which 'eliminates' it. The introductions represent the 'definitions' of the symbols concerned, and eliminations are consequences of these. | |
| From: Gerhard Gentzen (works [1938], II.5.13), quoted by Ian Rumfitt - "Yes" and "No" III | |
| A reaction: [1935 paper] This passage is famous, in laying down the basics of natural deduction systems of logic (ones using only rules, and avoiding axioms). Rumfitt questions whether Gentzen's account gives the sense of the connectives. |
| 13832 | Natural deduction shows the heart of reasoning (and sequent calculus is just a tool) [Gentzen, by Hacking] |
| Full Idea: Gentzen thought that his natural deduction gets at the heart of logical reasoning, and used the sequent calculus only as a convenient tool for proving his chief results. | |
| From: report of Gerhard Gentzen (Investigations into Logical Deduction [1935]) by Ian Hacking - What is Logic? §05 |
| 10067 | Gentzen proved the consistency of arithmetic from assumptions beyond arithmetic [Gentzen, by Musgrave] |
| Full Idea: Gentzen proved the consistency of arithmetic from assumptions which transcend arithmetic. | |
| From: report of Gerhard Gentzen (works [1938]) by Alan Musgrave - Logicism Revisited §5 | |
| A reaction: This does not contradict Gödel's famous result, but reinforces it. The interesting question is what assumptions Gentzen felt he had to make. |
| 9275 | Knowledge does not need minds or nervous systems; it is found in all living things [Gray] |
| Full Idea: Knowledge does not need minds, or even nervous systems. It is found in all living things. | |
| From: John Gray (Straw Dogs [2002], 2.10) | |
| A reaction: I consider it a misnomer to call such things 'knowledge', for which I have much higher standards. Gray is talking about 'information'. Knowledge needs reasons, and possibility of error, not just anticipatory behaviour. |
| 3916 | Hopi consistently prefers verbs and events to nouns and things [Whorf] |
| Full Idea: Hopi, with its preference for verbs, as contrasted to our own liking for nouns, perpetually turns our propositions about things into propositions about events. | |
| From: Benjamin Lee Whorf (An American Indian model of the Universe [1936], p.63) | |
| A reaction: This should provoke careful thought about ontology - without concluding that it is entirely relative to language. |
| 3914 | Language arranges sensory experience to form a world-order [Whorf] |
| Full Idea: Language first of all is a classification and arrangement of the stream of sensory experience which results in a certain world-order. | |
| From: Benjamin Lee Whorf (Punctual and segmentive Hopi verbs [1936], p.55) | |
| A reaction: This is only true to a limited degree. See Davidson's 'On the very idea of a conceptual scheme'. All humans share a world-order, to some extent. |
| 3917 | Scientific thought is essentially a specialised part of Indo-European languages [Whorf] |
| Full Idea: What we call "scientific thought" is a specialisation of the western Indo-European type of language. | |
| From: Benjamin Lee Whorf (An American Indian model of the Universe [1936], p.246) | |
| A reaction: This is the beginnings of an absurd extreme relativist view of science, based on a confusion about meaning and thought. |
| 9276 | The will hardly ever does anything; most of our life just happens to us [Gray] |
| Full Idea: We think our actions express our decisions, but in nearly all of our life, willing decides nothing. We cannot wake up or fall asleep, remember or forget our dreams, summon or banish our thoughts, by deciding to do so. | |
| From: John Gray (Straw Dogs [2002], 2.12) | |
| A reaction: Gray's point does not rule out occasional total control over mental life, but his point is important. The traditional picture is of a life controlled, so the will is seen as at the centre of a person, but it just isn't the case. |
| 9278 | Nowadays we identify the free life with the good life [Gray] |
| Full Idea: We do not value freedom more than people did in earlier times, but we have identified the good life with the chosen life. | |
| From: John Gray (Straw Dogs [2002], 3.13) | |
| A reaction: Interesting. This is Enlightenment liberalism gradually filtering down into common consciousness, especially via the hegemony of American culture. I sympathise the Gray; don't get me wrong, but I think freedom is overrated. |
| 3915 | The Hopi have no concept of time as something flowing from past to future [Whorf] |
| Full Idea: A Hopi has no general notion or intuition of time as a smooth flowing continuum in which everything in the universe proceeds at an equal rate, out of a future, through a present, into a past. | |
| From: Benjamin Lee Whorf (An American Indian model of the Universe [1936], p.57) | |
| A reaction: If true, this would not so much support relativism of language as the view that that conception of time is actually false. |
| 9280 | Over forty percent of the Earth's living tissue is human [Gray] |
| Full Idea: Humans co-opt over forty per cent of the Earth's living tissue. | |
| From: John Gray (Straw Dogs [2002], 4.15) | |
| A reaction: If you add our domestic animals, I understand that the figure goes up to 95 per cent! I take this to be virtually the only significant ecological fact - population, population, population. Why are there so many cars? So many carbon footprints? |
| 23061 | Free atheism should start by questioning its faith in humanity [Gray] |
| Full Idea: A free-thinking atheism would begin by questioning the prevailing faith in humanity. But there is little prospect of contemporary atheists giving up their reverence for this phantom. | |
| From: John Gray (Seven Types of Atheism [2018], Conc) | |
| A reaction: He seems to be referring to 'humanism', which I take to be quite different from atheism. I take it as obvious that simple atheism is entirely neutral on the question of whether we should have 'faith' in humanity (which presumably mean optimism). |
| 23057 | Gnosticism has a supreme creator God, giving way to a possibly hostile Demiurge [Gray] |
| Full Idea: Gnostic traditions envisage a supreme God that created the universe and then withdrew into itself, leaving the world to be ruled by a lesser god, or Demiurge, which might be indifferent or hostile to mankind. | |
| From: John Gray (Seven Types of Atheism [2018], Intro) | |
| A reaction: It doesn't seem to solve any problems, given that the first God is 'supreme', and is therefore responsible for the introduction and actions of the later Demiurge. |
| 23056 | Judaism only became monotheistic around 550 BCE [Gray] |
| Full Idea: It was only sometime around the sixth century BC, during the period when the Israelites returned to Jerusalem, that the idea that there is only one God emerged in Jewish religion. | |
| From: John Gray (Seven Types of Atheism [2018], Intro) | |
| A reaction: There seems to be a parallel move among the Greeks to elevate Zeus to special status. |
| 9272 | Without Christianity we lose the idea that human history has a meaning [Gray] |
| Full Idea: For Christians, it is because they occur in history that the lives of humans have a meaning that the lives of other animals do not. ..If we truly leave Christianity behind, we must give up the idea that human history has a meaning. | |
| From: John Gray (Straw Dogs [2002], 2.3) | |
| A reaction: Interesting. Compare the dispute between 'whig' and 'tory' historians, the former of whom believe that history is going somewhere. |
| 9279 | What was our original sin, and how could Christ's suffering redeem it? [Gray] |
| Full Idea: No one can say what was humankind's original sin, and no one understands how the suffering of Christ can redeem it. | |
| From: John Gray (Straw Dogs [2002], 4.1) | |
| A reaction: This nicely articulates a problem that has half bothered me, but I have never put into words. I always assumed Eve committed the sin, and Adam cops the blame for not controlling his woman. Dying for our sins has always puzzled me. |
| 23055 | Christians introduced the idea that a religion needs a creed [Gray] |
| Full Idea: The notion that religions are creeds - lists of propositions or doctrines that everyone must accept or reject - emerged only with Christianity. | |
| From: John Gray (Seven Types of Atheism [2018], Intro) | |
| A reaction: With a creed comes the possibility of heresy. I''m not happy with children being taught to recite something which begins 'I believe…', but which they have never thought about and barely understand. |
| 23058 | Buddhism has no divinity or souls, and the aim is to lose the illusion of a self [Gray] |
| Full Idea: Buddhism says nothing of any divine mind and rejects any idea of the soul. The world consists of processes and events. The human sense of self is an illusion; freedom is found in ridding oneself of this illusion. | |
| From: John Gray (Seven Types of Atheism [2018], Intro) | |
| A reaction: I'm not clear why shaking off the illusion of a self is a superior state. Freedom to do what? Presumably nothing at all, since there is no self to desire anything. |