150 ideas
| 1597 | Thales was the first western thinker to believe the arché was intelligible [Roochnik on Thales] |
| 9123 | Someone standing in a doorway seems to be both in and not-in the room [Priest,G, by Sorensen] |
| 8720 | A logic is 'relevant' if premise and conclusion are connected, and 'paraconsistent' allows contradictions [Priest,G, by Friend] |
| 9672 | Free logic is one of the few first-order non-classical logics [Priest,G] |
| 9697 | X1 x X2 x X3... x Xn indicates the 'cartesian product' of those sets [Priest,G] |
| 9685 | <a,b&62; is a set whose members occur in the order shown [Priest,G] |
| 9675 | a ∈ X says a is an object in set X; a ∉ X says a is not in X [Priest,G] |
| 9674 | {x; A(x)} is a set of objects satisfying the condition A(x) [Priest,G] |
| 9673 | {a1, a2, ...an} indicates that a set comprising just those objects [Priest,G] |
| 9677 | Φ indicates the empty set, which has no members [Priest,G] |
| 9676 | {a} is the 'singleton' set of a (not the object a itself) [Priest,G] |
| 9679 | X⊂Y means set X is a 'proper subset' of set Y [Priest,G] |
| 9678 | X⊆Y means set X is a 'subset' of set Y [Priest,G] |
| 9681 | X = Y means the set X equals the set Y [Priest,G] |
| 9683 | X ∩ Y indicates the 'intersection' of sets X and Y, the objects which are in both sets [Priest,G] |
| 9682 | X∪Y indicates the 'union' of all the things in sets X and Y [Priest,G] |
| 9684 | Y - X is the 'relative complement' of X with respect to Y; the things in Y that are not in X [Priest,G] |
| 9694 | The 'relative complement' is things in the second set not in the first [Priest,G] |
| 9693 | The 'intersection' of two sets is a set of the things that are in both sets [Priest,G] |
| 9692 | The 'union' of two sets is a set containing all the things in either of the sets [Priest,G] |
| 9698 | The 'induction clause' says complex formulas retain the properties of their basic formulas [Priest,G] |
| 9695 | An 'ordered pair' (or ordered n-tuple) is a set with its members in a particular order [Priest,G] |
| 9696 | A 'cartesian product' of sets is the set of all the n-tuples with one member in each of the sets [Priest,G] |
| 9686 | A 'set' is a collection of objects [Priest,G] |
| 9689 | The 'empty set' or 'null set' has no members [Priest,G] |
| 9690 | A set is a 'subset' of another set if all of its members are in that set [Priest,G] |
| 9691 | A 'proper subset' is smaller than the containing set [Priest,G] |
| 9688 | A 'singleton' is a set with only one member [Priest,G] |
| 9687 | A 'member' of a set is one of the objects in the set [Priest,G] |
| 9680 | The empty set Φ is a subset of every set (including itself) [Priest,G] |
| 8625 | What physical facts could underlie 0 or 1, or very large numbers? [Frege on Mill] |
| 17895 | Combining two distinct assertions does not necessarily lead to a single 'complex proposition' [Mill] |
| 10427 | All names are names of something, real or imaginary [Mill] |
| 4944 | Mill says names have denotation but not connotation [Mill, by Kripke] |
| 7762 | Proper names are just labels for persons or objects, and the meaning is the object [Mill, by Lycan] |
| 13373 | Typically, paradoxes are dealt with by dividing them into two groups, but the division is wrong [Priest,G] |
| 13368 | The 'least indefinable ordinal' is defined by that very phrase [Priest,G] |
| 13370 | 'x is a natural number definable in less than 19 words' leads to contradiction [Priest,G] |
| 13369 | By diagonalization we can define a real number that isn't in the definable set of reals [Priest,G] |
| 13366 | The least ordinal greater than the set of all ordinals is both one of them and not one of them [Priest,G] |
| 13367 | The next set up in the hierarchy of sets seems to be both a member and not a member of it [Priest,G] |
| 13371 | If you know that a sentence is not one of the known sentences, you know its truth [Priest,G] |
| 13372 | There are Liar Pairs, and Liar Chains, which fit the same pattern as the basic Liar [Priest,G] |
| 9801 | Numbers must be assumed to have identical units, as horses are equalised in 'horse-power' [Mill] |
| 8742 | The only axioms needed are for equality, addition, and successive numbers [Mill, by Shapiro] |
| 9800 | Arithmetic is based on definitions, and Sums of equals are equal, and Differences of equals are equal [Mill] |
| 5201 | Mill says logic and maths is induction based on a very large number of instances [Mill, by Ayer] |
| 9360 | If two black and two white objects in practice produced five, what colour is the fifth one? [Lewis,CI on Mill] |
| 9888 | Mill mistakes particular applications as integral to arithmetic, instead of general patterns [Dummett on Mill] |
| 9794 | There are no such things as numbers in the abstract [Mill] |
| 9796 | Things possess the properties of numbers, as quantity, and as countable parts [Mill] |
| 9795 | Numbers have generalised application to entities (such as bodies or sounds) [Mill] |
| 9798 | Different parcels made from three pebbles produce different actual sensations [Mill] |
| 9797 | '2 pebbles and 1 pebble' and '3 pebbles' name the same aggregation, but different facts [Mill] |
| 9799 | 3=2+1 presupposes collections of objects ('Threes'), which may be divided thus [Mill] |
| 9802 | Numbers denote physical properties of physical phenomena [Mill] |
| 9803 | We can't easily distinguish 102 horses from 103, but we could arrange them to make it obvious [Mill] |
| 9804 | Arithmetical results give a mode of formation of a given number [Mill] |
| 9805 | 12 is the cube of 1728 means pebbles can be aggregated a certain way [Mill] |
| 8741 | Numbers must be of something; they don't exist as abstractions [Mill] |
| 12411 | Mill is too imprecise, and is restricted to simple arithmetic [Kitcher on Mill] |
| 5656 | Empirical theories of arithmetic ignore zero, limit our maths, and need probability to get started [Frege on Mill] |
| 9624 | Numbers are a very general property of objects [Mill, by Brown,JR] |
| 9806 | Whatever is made up of parts is made up of parts of those parts [Mill] |
| 11156 | The essence is that without which a thing can neither be, nor be conceived to be [Mill] |
| 12190 | Necessity is what will be, despite any alternative suppositions whatever [Mill] |
| 22623 | Necessity can only mean what must be, without conditions of any kind [Mill] |
| 3013 | Nothing is stronger than necessity, which rules everything [Thales, by Diog. Laertius] |
| 3583 | External objects are permanent possibilities of sensation [Mill] |
| 16859 | Most perception is one-tenth observation and nine-tenths inference [Mill] |
| 9082 | Clear concepts result from good observation, extensive experience, and accurate memory [Mill] |
| 16860 | Inductive generalisation is more reliable than one of its instances; they can't all be wrong [Mill] |
| 16845 | The whole theory of induction rests on causes [Mill] |
| 16843 | Mill's methods (Difference,Agreement,Residues,Concomitance,Hypothesis) don't nail induction [Mill, by Lipton] |
| 17086 | Surprisingly, empiricists before Mill ignore explanation, which seems to transcend experience [Mill, by Ruben] |
| 17091 | Explanation is fitting of facts into ever more general patterns of regularity [Mill, by Ruben] |
| 16805 | Causal inference is by spotting either Agreements or Differences [Mill, by Lipton] |
| 16835 | The Methods of Difference and of Agreement are forms of inference to the best explanation [Mill, by Lipton] |
| 3537 | I judge others' feeling by analogy with my body and behaviour [Mill] |
| 9079 | We can focus our minds on what is common to a whole class, neglecting other aspects [Mill] |
| 9081 | We don't recognise comparisons by something in our minds; the concepts result from the comparisons [Mill] |
| 9080 | General conceptions are a necessary preliminary to Induction [Mill] |
| 9078 | The study of the nature of Abstract Ideas does not belong to logic, but to a different science [Mill] |
| 3772 | The will, in the beginning, is entirely produced by desire [Mill] |
| 7222 | It is a crime for someone with a violent disposition to get drunk [Mill] |
| 3769 | With early training, any absurdity or evil may be given the power of conscience [Mill] |
| 3767 | Motive shows the worth of the agent, but not of the action [Mill] |
| 7076 | Mill wondered if he would be happy if all his aims were realised, and answered no [Mill, by Critchley] |
| 3771 | Virtues only have value because they achieve some further end [Mill] |
| 3768 | Orthodox morality is the only one which feels obligatory [Mill] |
| 7214 | Ethics rests on utility, which is the permanent progressive interests of people [Mill] |
| 7202 | The English believe in the task of annihilating evil for the victory of good [Nietzsche on Mill] |
| 5935 | Mill's qualities of pleasure is an admission that there are other good states of mind than pleasure [Ross on Mill] |
| 3764 | Actions are right if they promote pleasure, wrong if they promote pain [Mill] |
| 3776 | Utilitarianism only works if everybody has a totally equal right to happiness [Mill] |
| 3765 | Only pleasure and freedom from pain are desirable as ends [Mill] |
| 3763 | Ultimate goods such as pleasure can never be proved to be good [Mill] |
| 3766 | Better to be Socrates dissatisfied than a fool satisfied [Mill] |
| 3770 | General happiness is only desirable because individuals desire their own happiness [Mill] |
| 6697 | Moral rules protecting human welfare are more vital than local maxims [Mill] |
| 7212 | Individuals have sovereignty over their own bodies and minds [Mill] |
| 3773 | No individual has the right to receive our benevolence [Mill] |
| 3774 | Rights are a matter of justice, not of benevolence [Mill] |
| 7210 | The will of the people is that of the largest or most active part of the people [Mill] |
| 7227 | It is evil to give a government any more power than is necessary [Mill] |
| 7228 | Individuals often do things better than governments [Mill] |
| 7230 | Aim for the maximum dissemination of power consistent with efficiency [Mill] |
| 20515 | Maximise happiness by an area of strict privacy, and an area of utilitarian interventions [Mill, by Wolff,J] |
| 7229 | People who transact their own business will also have the initiative to control their government [Mill] |
| 20508 | How people vote should be on public record, so they can be held accountable [Mill, by Wolff,J] |
| 20507 | Voting is a strict duty, like jury service, and must only be aimed at the public good [Mill] |
| 20505 | Direct democracy is inexperience judging experience, and ignorance judging knowledge [Mill] |
| 20504 | People can only participate in decisions in small communities, so representatives are needed [Mill] |
| 7211 | Prevention of harm to others is the only justification for exercising power over people [Mill] |
| 7231 | The worth of a State, in the long run, is the worth of the individuals composing it [Mill] |
| 7217 | The main argument for freedom is that interference with it is usually misguided [Mill] |
| 7213 | Liberty arises at the point where people can freely and equally discuss things [Mill] |
| 20517 | Utilitarianism values liberty, but guides us on which ones we should have or not have [Mill, by Wolff,J] |
| 20516 | Mill defends freedom as increasing happiness, but maybe it is an intrinsic good [Wolff,J on Mill] |
| 7215 | True freedom is pursuing our own good, while not impeding others [Mill] |
| 7218 | Individuals are not accountable for actions which only concern themselves [Mill] |
| 7221 | Blocking entry to an unsafe bridge does not infringe liberty, since no one wants unsafe bridges [Mill] |
| 7223 | Pimping and running a gambling-house are on the border between toleration and restraint [Mill] |
| 7220 | Restraint for its own sake is an evil [Mill] |
| 3775 | A right is a valid claim to society's protection [Mill] |
| 7219 | Society can punish actions which it believes to be prejudicial to others [Mill] |
| 7226 | Benefits performed by individuals, not by government, help also to educate them [Mill] |
| 7224 | We need individual opinions and conduct, and State education is a means to prevent that [Mill] |
| 7225 | It is a crime to create a being who lacks the ordinary chances of a desirable existence [Mill] |
| 1494 | Thales said water is the first principle, perhaps from observing that food is moist [Thales, by Aristotle] |
| 8345 | A cause is the total of all the conditions which inevitably produce the result [Mill] |
| 10391 | Causes and conditions are not distinct, because we select capriciously from among them [Mill] |
| 14547 | The strict cause is the total positive and negative conditions which ensure the consequent [Mill] |
| 8377 | Causation is just invariability of succession between every natural fact and a preceding fact [Mill] |
| 14545 | A cause is an antecedent which invariably and unconditionally leads to a phenomenon [Mill] |
| 4773 | Mill's regularity theory of causation is based on an effect preceded by a conjunction of causes [Mill, by Psillos] |
| 4775 | In Mill's 'Method of Agreement' cause is the common factor in a range of different cases [Mill, by Psillos] |
| 4776 | In Mill's 'Method of Difference' the cause is what stops the effect when it is removed [Mill, by Psillos] |
| 9417 | What are the fewest propositions from which all natural uniformities could be inferred? [Mill] |
| 1713 | Thales must have thought soul causes movement, since he thought magnets have soul [Thales, by Aristotle] |
| 21332 | We don't get a love of 'order' from nature - which is thoroughly chaotic [Mill] |
| 1742 | Thales said the gods know our wrong thoughts as well as our evil actions [Thales, by Diog. Laertius] |
| 7216 | The ethics of the Gospel has been supplemented by barbarous Old Testament values [Mill] |
| 21333 | Evil comes from good just as often as good comes from evil [Mill] |
| 21335 | Belief that an afterlife is required for justice is an admission that this life is very unjust [Mill] |
| 21334 | No necessity ties an omnipotent Creator, so he evidently wills human misery [Mill] |
| 21329 | Nature dispenses cruelty with no concern for either mercy or justice [Mill] |
| 21328 | Killing is a human crime, but nature kills everyone, and often with great tortures [Mill] |
| 21330 | Nature makes childbirth a miserable experience, often leading to the death of the mother [Mill] |
| 21331 | Hurricanes, locusts, floods and blight can starve a million people to death [Mill] |