44 ideas
| 7454 | Gassendi is the first great empiricist philosopher [Hacking] |
| Full Idea: Gassendi is the first in the great line of empiricist philosophers that gradually came to dominate European thought. | |
| From: Ian Hacking (The Emergence of Probability [1975], Ch.5) | |
| A reaction: Epicurus, of course, was clearly an empiricist. British readers should note that Gassendi was not British. |
| 13838 | A decent modern definition should always imply a semantics [Hacking] |
| Full Idea: Today we expect that anything worth calling a definition should imply a semantics. | |
| From: Ian Hacking (What is Logic? [1979], §10) | |
| A reaction: He compares this with Gentzen 1935, who was attempting purely syntactic definitions of the logical connectives. |
| 13833 | 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking] |
| Full Idea: 'Dilution' (or 'Thinning') provides an essential contrast between deductive and inductive reasoning; for the introduction of new premises may spoil an inductive inference. | |
| From: Ian Hacking (What is Logic? [1979], §06.2) | |
| A reaction: That is, inductive logic (if there is such a thing) is clearly non-monotonic, whereas classical inductive logic is monotonic. |
| 13834 | Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking] |
| Full Idea: If A |- B and B |- C, then A |- C. This generalises to: If Γ|-A,Θ and Γ,A |- Θ, then Γ |- Θ. Gentzen called this 'cut'. It is the transitivity of a deduction. | |
| From: Ian Hacking (What is Logic? [1979], §06.3) | |
| A reaction: I read the generalisation as 'If A can be either a premise or a conclusion, you can bypass it'. The first version is just transitivity (which by-passes the middle step). |
| 13835 | Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking] |
| Full Idea: Only the cut rule can have a conclusion that is less complex than its premises. Hence when cut is not used, a derivation is quite literally constructive, building up from components. Any theorem obtained by cut can be obtained without it. | |
| From: Ian Hacking (What is Logic? [1979], §08) |
| 13845 | The various logics are abstractions made from terms like 'if...then' in English [Hacking] |
| Full Idea: I don't believe English is by nature classical or intuitionistic etc. These are abstractions made by logicians. Logicians attend to numerous different objects that might be served by 'If...then', like material conditional, strict or relevant implication. | |
| From: Ian Hacking (What is Logic? [1979], §15) | |
| A reaction: The idea that they are 'abstractions' is close to my heart. Abstractions from what? Surely 'if...then' has a standard character when employed in normal conversation? |
| 13840 | First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking] |
| Full Idea: First-order logic is the strongest complete compact theory with a Löwenheim-Skolem theorem. | |
| From: Ian Hacking (What is Logic? [1979], §13) |
| 13844 | A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking] |
| Full Idea: Henkin proved that there is no first-order treatment of branching quantifiers, which do not seem to involve any idea that is fundamentally different from ordinary quantification. | |
| From: Ian Hacking (What is Logic? [1979], §13) | |
| A reaction: See Hacking for an example of branching quantifiers. Hacking is impressed by this as a real limitation of the first-order logic which he generally favours. |
| 13842 | Second-order completeness seems to need intensional entities and possible worlds [Hacking] |
| Full Idea: Second-order logic has no chance of a completeness theorem unless one ventures into intensional entities and possible worlds. | |
| From: Ian Hacking (What is Logic? [1979], §13) |
| 13837 | With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking] |
| Full Idea: My doctrine is that the peculiarity of the logical constants resides precisely in that given a certain pure notion of truth and consequence, all the desirable semantic properties of the constants are determined by their syntactic properties. | |
| From: Ian Hacking (What is Logic? [1979], §09) | |
| A reaction: He opposes this to Peacocke 1976, who claims that the logical connectives are essentially semantic in character, concerned with the preservation of truth. |
| 13839 | Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking] |
| Full Idea: For some purposes the variables of first-order logic can be regarded as prepositions and place-holders that could in principle be dispensed with, say by a system of arrows indicating what places fall in the scope of which quantifier. | |
| From: Ian Hacking (What is Logic? [1979], §11) | |
| A reaction: I tend to think of variables as either pronouns, or as definite descriptions, or as temporary names, but not as prepositions. Must address this new idea... |
| 13843 | If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking] |
| Full Idea: A Löwenheim-Skolem theorem holds for anything which, on my delineation, is a logic. | |
| From: Ian Hacking (What is Logic? [1979], §13) | |
| A reaction: I take this to be an unusually conservative view. Shapiro is the chap who can give you an alternative view of these things, or Boolos. |
| 21554 | Sets always exceed terms, so all the sets must exceed all the sets [Lackey] |
| Full Idea: Cantor proved that the number of sets in a collection of terms is larger than the number of terms. Hence Cantor's Paradox says the number of sets in the collection of all sets must be larger than the number of sets in the collection of all sets. | |
| From: Douglas Lackey (Intros to Russell's 'Essays in Analysis' [1973], p.127) | |
| A reaction: The sets must count as terms in the next iteration, but that is a normal application of the Power Set axiom. |
| 21553 | It seems that the ordinal number of all the ordinals must be bigger than itself [Lackey] |
| Full Idea: The ordinal series is well-ordered and thus has an ordinal number, and a series of ordinals to a given ordinal exceeds that ordinal by 1. So the series of all ordinals has an ordinal number that exceeds its own ordinal number by 1. | |
| From: Douglas Lackey (Intros to Russell's 'Essays in Analysis' [1973], p.127) | |
| A reaction: Formulated by Burali-Forti in 1897. |
| 9240 | Love creates a necessity concerning what to care about [Frankfurt] |
| Full Idea: The necessity with which love binds the will puts an end to indecisiveness concerning what to care about. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 2.13) | |
| A reaction: I put this here as a reminder that there may be more to necessity than the dry concept of metaphysicians and logicians. 'Why did you rescue that man first?' 'Because I love him'. Kit Fine recognises many sorts of necessity. |
| 7447 | Probability was fully explained between 1654 and 1812 [Hacking] |
| Full Idea: There is hardly any history of probability to record before Pascal (1654), and the whole subject is very well understood after Laplace (1812). | |
| From: Ian Hacking (The Emergence of Probability [1975], Ch.1) | |
| A reaction: An interesting little pointer on the question of whether the human race is close to exhausting all the available intellectual problems. What then? |
| 7448 | Probability is statistical (behaviour of chance devices) or epistemological (belief based on evidence) [Hacking] |
| Full Idea: Probability has two aspects: the degree of belief warranted by evidence, and the tendency displayed by some chance device to produce stable relative frequencies. These are the epistemological and statistical aspects of the subject. | |
| From: Ian Hacking (The Emergence of Probability [1975], Ch.1) | |
| A reaction: The most basic distinction in the subject. Later (p.124) he suggests that the statistical form (known as 'aleatory' probability) is de re, and the other is de dicto. |
| 7449 | Epistemological probability based either on logical implications or coherent judgments [Hacking] |
| Full Idea: Epistemological probability is torn between Keynes etc saying it depends on the strength of logical implication, and Ramsey etc saying it is personal judgement which is subject to strong rules of internal coherence. | |
| From: Ian Hacking (The Emergence of Probability [1975], Ch.2) | |
| A reaction: See Idea 7449 for epistemological probability. My immediate intuition is that the Ramsey approach sounds much more plausible. In real life there are too many fine-grained particulars involved for straight implication to settle a probability. |
| 7450 | In the medieval view, only deduction counted as true evidence [Hacking] |
| Full Idea: In the medieval view, evidence short of deduction was not really evidence at all. | |
| From: Ian Hacking (The Emergence of Probability [1975], Ch.3) | |
| A reaction: Hacking says the modern concept of evidence comes with probability in the 17th century. That might make it one of the most important ideas ever thought of, allowing us to abandon certainties and live our lives in a more questioning way. |
| 7451 | Formerly evidence came from people; the new idea was that things provided evidence [Hacking] |
| Full Idea: In the medieval view, people provided the evidence of testimony and of authority. What was lacking was the seventeenth century idea of the evidence provided by things. | |
| From: Ian Hacking (The Emergence of Probability [1975], Ch.4) | |
| A reaction: A most intriguing distinction, which seems to imply a huge shift in world-view. The culmination of this is Peirce's pragmatism, in Idea 6948, of which I strongly approve. |
| 7452 | An experiment is a test, or an adventure, or a diagnosis, or a dissection [Hacking, by PG] |
| Full Idea: An experiment is a test (if T, then E implies R, so try E, and if R follows, T seems right), an adventure (no theory, but try things), a diagnosis (reading the signs), or a dissection (taking apart). | |
| From: report of Ian Hacking (The Emergence of Probability [1975], Ch.4) by PG - Db (ideas) | |
| A reaction: A nice analysis. The Greeks did diagnosis, then the alchemists tried adventures, then Vesalius began dissections, then the followers of Bacon concentrated on the test, setting up controlled conditions. 'If you don't believe it, try it yourself'. |
| 7459 | Follow maths for necessary truths, and jurisprudence for contingent truths [Hacking] |
| Full Idea: Mathematics is the model for reasoning about necessary truths, but jurisprudence must be our model when we deliberate about contingencies. | |
| From: Ian Hacking (The Emergence of Probability [1975], Ch.10) | |
| A reaction: Interesting. Certainly huge thinking, especially since the Romans, has gone into the law, and creating rules of evidence. Maybe all philosophers should study law and mathematics? |
| 9264 | Persons are distinguished by a capacity for second-order desires [Frankfurt] |
| Full Idea: The essential difference between persons and other creatures is in the structure of the will, with their peculiar characteristic of being able to form 'second-order desires'. | |
| From: Harry G. Frankfurt (Freedom of the Will and concept of a person [1971], Intro) | |
| A reaction: There are problems with this - notably that all strategies of this kind just shift the problem up to the next order, without solving it - but this still strikes me as a very promising line of thinking when trying to understand ourselves. See Idea 9266. |
| 9266 | A person essentially has second-order volitions, and not just second-order desires [Frankfurt] |
| Full Idea: It is having second-order volitions, and not having second-order desires generally, that I regard as essential to being a person. | |
| From: Harry G. Frankfurt (Freedom of the Will and concept of a person [1971], §II) | |
| A reaction: Watson criticises Frankfurt for just pushing the problem up to the the next level, but Frankfurt is not offering to explain the will. He merely notes that this structure produces the sort of behaviour which is characteristic of persons, and he is right. |
| 9267 | Free will is the capacity to choose what sort of will you have [Frankfurt] |
| Full Idea: The statement that a person enjoys freedom of the will means that he is free to want what he wants to want. More precisely, he is free to will what he wants to will, or to have the will he wants. | |
| From: Harry G. Frankfurt (Freedom of the Will and concept of a person [1971], §III) | |
| A reaction: A good proposal. It covers kleptomaniacs and drug addicts quite well. Thieves have second-order desires (to steal) of which kleptomaniacs are incapable. There is actually no such thing as free will, but this sort of thing will do. |
| 9265 | The will is the effective desire which actually leads to an action [Frankfurt] |
| Full Idea: A person's will is the effective desire which moves (or will or would move) a person all the way to action. The will is not coextensive with what an agent intends to do, since he may do something else instead. | |
| From: Harry G. Frankfurt (Freedom of the Will and concept of a person [1971], §I) | |
| A reaction: Essentially Hobbes's view, but with an arbitrary distinction added. If the desire is only definitely a 'will' if it really does lead to action, then it only becomes the will after the action starts. The error is thinking that will is all-or-nothing. |
| 20015 | Freedom of action needs the agent to identify with their reason for acting [Frankfurt, by Wilson/Schpall] |
| Full Idea: Frankfurt says that basic issues concerning freedom of action presuppose and give weight to a concept of 'acting on a desire with which the agent identifies'. | |
| From: report of Harry G. Frankfurt (Freedom of the Will and concept of a person [1971]) by Wilson,G/Schpall,S - Action 1 | |
| A reaction: [the cite Frankfurt 1988 and 1999] I'm not sure how that works when performing a grim duty, but it sounds quite plausible. |
| 9228 | Ranking order of desires reveals nothing, because none of them may be considered important [Frankfurt] |
| Full Idea: Ranking desires in order of preference is no help, because a person who wants one thing more than another may not regard the former as any more important to him than the latter. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 1.5) | |
| A reaction: A salutary warning. Someone may pursue something with incredible intensity, but only to stave off a boring and empty existence. The only way I can think of to assess what really matters to people is - to ask them! |
| 9270 | A 'wanton' is not a person, because they lack second-order volitions [Frankfurt] |
| Full Idea: I use the term 'wanton' to refer to agents who have first-order desires but who are not persons because, whether or not they have desires of the second-order, they have no second-order volitions. | |
| From: Harry G. Frankfurt (Freedom of the Will and concept of a person [1971], §II) | |
| A reaction: He seems to be describing someone who behaves like an animal, performing actions without ever stopping to think about them. Presumably some persons occasionally become wantons, if, for example, they have an anger problem. |
| 9269 | A person may be morally responsible without free will [Frankfurt] |
| Full Idea: It is not true that a person is morally responsible for what he has done only if his will was free when he did it. He may be morally responsible for having done it even though his will was not free at all. | |
| From: Harry G. Frankfurt (Freedom of the Will and concept of a person [1971], §IV) | |
| A reaction: Frankfurt seems to be one of the first to assert this break with the traditional view. Good for him. I take moral responsibility to hinge on an action being caused by a person, but not with a mystical view of what a person is. |
| 9238 | Morality isn't based on reason; moral indignation is quite unlike disapproval of irrationality [Frankfurt] |
| Full Idea: The ultimate warrant for moral principles cannot be found in reason. The sort of opprobrium that attaches to moral transgressions is quite unlike the sort of opprobrium that attaches to the requirements of reason. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 2.5 n6) | |
| A reaction: More like a piece of evidence than a proper argument. We may not feel indignant if someone fails a maths exam, but we might if they mess up the arithmetic of our bank account, even though they meant well. |
| 9232 | It is by caring about things that we infuse the world with importance [Frankfurt] |
| Full Idea: It is by caring about things that we infuse the world with importance. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 1.10) | |
| A reaction: This book is a lovely attempt at getting to the heart of where values come from. 'Football isn't a matter of life and death; it's more important than that' - Bill Shankly (manager of Liverpool). Frankfurt is right. |
| 9234 | If you don't care about at least one thing, you can't find reasons to care about anything [Frankfurt] |
| Full Idea: It is not possible for a person who does not already care at least about something to discover reasons for caring about anything. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 1.11) | |
| A reaction: This is the key idea of this lovely book. Without a glimmer of love somewhere, it is not possible to bootstrap a meaningful life. The glimmer of caring about one thing is transferable. See the Ancient Mariner and the watersnake. |
| 9229 | What is worthwhile for its own sake alone may be worth very little [Frankfurt] |
| Full Idea: What is worth having or worth doing for its own sake alone may nonetheless be worth very little. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 1.5) | |
| A reaction: That is one of my cherished notions sunk without trace! Aristotle's idea that ends are what matter, not means, always struck me as crucial. But Frankfurt is right. Collecting trivia is done for its own sake. Great tasks are performed as a means. |
| 9233 | Our criteria for evaluating how to live offer an answer to the problem [Frankfurt] |
| Full Idea: Identifying the criteria to be employed in evaluating various ways of living is also tantamount to providing an answer to the question of how to live. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 1.10) | |
| A reaction: Presumably critical reflection is still possible about those criteria, even though he implies that they just arise out of you (in a rather Nietzschean way). The fear is that critical reflection on basic criteria kills in infant in its cradle. |
| 9235 | Rather than loving things because we value them, I think we value things because we love them [Frankfurt] |
| Full Idea: It is often understood that we begin loving things because we are struck by their value. ..However, what I have in mind is rather that what we love necessarily acquires value for us because we love it. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 2.3) | |
| A reaction: The uneasy thought here is that this makes value much less rational. If you love because you value, you could probably give reasons for the value. If love comes first it must be instinctive. He says he loved his children before they were born. |
| 9236 | Love can be cool, and it may not involve liking its object [Frankfurt] |
| Full Idea: It is not among the defining features of love that it must be hot rather than cool, ..and nor is it essential that a person like what he loves. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 2.4) | |
| A reaction: An interesting pair of observations. The greatness of love would probably be measured by length, or by sacrifice. Extreme heat makes us a little suspicious. It would be hard to love something that was actually disliked. |
| 9237 | The paradigm case of pure love is not romantic, but that between parents and infants [Frankfurt] |
| Full Idea: Relationships that are primarily romantic or sexual do not provide very authentic or illuminating paradigms of love. ...The love of parents for their small children comes closest to offering recognizably pure instances of love. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 2.4) | |
| A reaction: Excellent. Though perhaps a relationships which began romantically might settle into something like the more 'pure' love that he has in mind. Such a relationship must, I trust, be possible between adults. |
| 9239 | I value my children for their sake, but I also value my love for them for its own sake [Frankfurt] |
| Full Idea: Beside the fact that my children are important to me for their own sakes, there is the additional fact that loving my children is important to me for its own sake. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 2.7) | |
| A reaction: This is at the heart of Frankfurt's thesis, that love is the bedrock of our values in life, and we therefore all need to love in order to generate any values in our life, quite apart from what our love is directed at. Nice thought. |
| 9227 | We might not choose a very moral life, if the character or constitution was deficient [Frankfurt] |
| Full Idea: People who are scrupulously moral may nonetheless be destined by deficiencies of character or of constitution to lead lives that no reasonable person would freely choose. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 1.2) | |
| A reaction: This fairly firmly refutes any Greek dream that all there is to happiness is leading a virtuous life. Frankfurt is with Aristotle more than with the Stoics. It would be tempting to sacrifice virtue to get a sunny character and good health. |
| 9230 | People want to fulfill their desires, but also for their desires to be sustained [Frankfurt] |
| Full Idea: Besides wanting to fulfil his desire, the person who cares about what he desires wants something else as well: he wants the desire to be sustained. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 1.6) | |
| A reaction: Plato, in 'Gorgias', makes this fact sound like a nightmare, resembling drug addiction, but in Frankfurt's formulation it looks like a good thing. If you want to make your family happy because you love them, you would dread finding your love had died. |
| 9241 | Loving oneself is not a failing, but is essential to a successful life [Frankfurt] |
| Full Idea: Far from demonstrating a flaw in character or being a sign of weakness, coming to love oneself is the deepest and most essential - and by no means the most readily attainable - achievement of a serious and successful life. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 2.14) | |
| A reaction: Obviously it will be necessary to dilineate the healthy form of self-love, which Frankfurt attempts to do. Ruthless vanity and self-seeking certainly look like the worst possible weaknesses of character. With that proviso, he is right. |
| 9300 | Boredom is serious, not just uncomfortable; it threatens our psychic survival [Frankfurt] |
| Full Idea: Boredom is a serious matter. It is not a condition that we seek to avoid just because we do not find it enjoyable. ..It threatens the very continuation of conscious mental life. ..Avoiding bored is a primitive urge for psychic survival. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 2.8) | |
| A reaction: Presumably nihilism will flood into the emptiness created by boredom. Frankfurt will see it as a lack of love for anything in your life, and hence an absence of value. Frankfurt is very good. |
| 9231 | Freedom needs autonomy (rather than causal independence) - embracing our own desires and choices [Frankfurt] |
| Full Idea: What counts as far as freedom goes is not causal independence, but autonomy. It is a matter of whether we are active rather than passive in our motives and choices, whether those are what we really want, and not alien to us. | |
| From: Harry G. Frankfurt (The Reasons of Love [2005], 1.8) | |
| A reaction: This is why setting your own targets is excellent, but having targets set for you by authorities is pernicious. These kind of principles need to be clear before any plausible theory of liberalism can be developed. |