89 ideas
| 20910 | Everything happens necessarily, and for a reason [Democritus] |
| Full Idea: Nothing happens at random, but everything for a reason and as the effect of necessity. | |
| From: Democritus (fragments/reports [c.431 BCE], B002), quoted by Pseudo-Plutarch - On the Doctrine of the Philosophers 1.25.4 | |
| A reaction: [In Aetius 'Stob'] This remark reminds us of the link between necessity and sufficient reason. Do all reasons arise for a reason? |
| 9641 | Definitions should be replaceable by primitives, and should not be creative [Brown,JR] |
| Full Idea: The standard requirement of definitions involves 'eliminability' (any defined terms must be replaceable by primitives) and 'non-creativity' (proofs of theorems should not depend on the definition). | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 7) | |
| A reaction: [He cites Russell and Whitehead as a source for this view] This is the austere view of the mathematician or logician. But almost every abstract concept that we use was actually defined in a creative way. |
| 9634 | Set theory says that natural numbers are an actual infinity (to accommodate their powerset) [Brown,JR] |
| Full Idea: The set-theory account of infinity doesn't just say that we can keep on counting, but that the natural numbers are an actual infinite set. This is necessary to make sense of the powerset of ω, as the set of all its subsets, and thus even bigger. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 5) | |
| A reaction: I don't personally find this to be sufficient reason to commit myself to the existence of actual infinities. In fact I have growing doubts about the whole role of set theory in philosophy of mathematics. Shows how much I know. |
| 9613 | Naïve set theory assumed that there is a set for every condition [Brown,JR] |
| Full Idea: In the early versions of set theory ('naïve' set theory), the axiom of comprehension assumed that for any condition there is a set of objects satisfying that condition (so P(x)↔x∈{x:P(x)}), but this led directly to Russell's Paradox. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 2) | |
| A reaction: How rarely any philosophers state this problem clearly (as Brown does here). This is incredibly important for our understanding of how we classify the world. I'm tempted to just ignore Russell, and treat sets in a natural and sensible way. |
| 9615 | Nowadays conditions are only defined on existing sets [Brown,JR] |
| Full Idea: In current set theory Russell's Paradox is avoided by saying that a condition can only be defined on already existing sets. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 2) | |
| A reaction: A response to Idea 9613. This leaves us with no account of how sets are created, so we have the modern notion that absolutely any grouping of daft things is a perfectly good set. The logicians seem to have hijacked common sense. |
| 9617 | The 'iterative' view says sets start with the empty set and build up [Brown,JR] |
| Full Idea: The modern 'iterative' concept of a set starts with the empty set φ (or unsetted individuals), then uses set-forming operations (characterized by the axioms) to build up ever more complex sets. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 2) | |
| A reaction: The only sets in our system will be those we can construct, rather than anything accepted intuitively. It is more about building an elaborate machine that works than about giving a good model of reality. |
| 9642 | A flock of birds is not a set, because a set cannot go anywhere [Brown,JR] |
| Full Idea: Neither a flock of birds nor a pack of wolves is strictly a set, since a flock can fly south, and a pack can be on the prowl, whereas sets go nowhere and menace no one. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 7) | |
| A reaction: To say that the pack menaced you would presumably be to commit the fallacy of composition. Doesn't the number 64 have properties which its set-theoretic elements (whatever we decide they are) will lack? |
| 9605 | If a proposition is false, then its negation is true [Brown,JR] |
| Full Idea: The law of excluded middle says if a proposition is false, then its negation is true | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 1) | |
| A reaction: Surely that is the best statement of the law? How do you write that down? ¬(P)→¬P? No, because it is a semantic claim, not a syntactic claim, so a truth table captures it. Semantic claims are bigger than syntactic claims. |
| 9649 | Axioms are either self-evident, or stipulations, or fallible attempts [Brown,JR] |
| Full Idea: The three views one could adopt concerning axioms are that they are self-evident truths, or that they are arbitrary stipulations, or that they are fallible attempts to describe how things are. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch.10) | |
| A reaction: Presumably modern platonists like the third version, with others choosing the second, and hardly anyone now having the confidence to embrace the first. |
| 9638 | Berry's Paradox finds a contradiction in the naming of huge numbers [Brown,JR] |
| Full Idea: Berry's Paradox refers to 'the least integer not namable in fewer than nineteen syllables' - a paradox because it has just been named in eighteen syllables. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 5) | |
| A reaction: Apparently George Boolos used this quirky idea as a basis for a new and more streamlined proof of Gödel's Theorem. Don't tell me you don't find that impressive. |
| 9604 | Mathematics is the only place where we are sure we are right [Brown,JR] |
| Full Idea: Mathematics seems to be the one and only place where we humans can be absolutely sure that we got it right. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 1) | |
| A reaction: Apart from death and taxes, that is. Personally I am more certain of the keyboard I am typing on than I am of Pythagoras's Theorem, but the experts seem pretty confident about the number stuff. |
| 9622 | 'There are two apples' can be expressed logically, with no mention of numbers [Brown,JR] |
| Full Idea: 'There are two apples' can be recast as 'x is an apple and y is an apple, and x isn't y, and if z is an apple it is the same as x or y', which makes no appeal at all to mathematics. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 4) | |
| A reaction: He cites this as the basis of Hartry Field's claim that science can be done without numbers. The logic is ∃x∃y∀z(Ax&Ay&(x¬=y)&(Az→z=x∨z=y)). |
| 9648 | π is a 'transcendental' number, because it is not the solution of an equation [Brown,JR] |
| Full Idea: The number π is not only irrational, but it is also (unlike √2) a 'transcendental' number, because it is not the solution of an algebraic equation. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch.10) | |
| A reaction: So is that a superficial property, or a profound one? Answers on a post card. |
| 16146 | Two can't be a self-contained unit, because it would need to be one to do that [Democritus, by Aristotle] |
| Full Idea: Democritus claimed that one substance could not be composed from two nor two from one. …The same will clearly go for number, on the popular assumption that number is a combination of units. Unless two is one, it cannot contain a unit in actuality. | |
| From: report of Democritus (fragments/reports [c.431 BCE]) by Aristotle - Metaphysics 1039a15 | |
| A reaction: Chrysippus followed this up the first part with the memorable example of Dion and Theon. The problem with the second part is that 2, 3 and 4 are three numbers, so they can count as meta-units. |
| 9621 | Mathematics represents the world through structurally similar models. [Brown,JR] |
| Full Idea: Mathematics hooks onto the world by providing representations in the form of structurally similar models. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 4) | |
| A reaction: This is Brown's conclusion. It needs notions of mapping, one-to-one correspondence, and similarity. I like the idea of a 'model', as used in both logic and mathematics, and children's hobbies. The mind is a model-making machine. |
| 9646 | There is no limit to how many ways something can be proved in mathematics [Brown,JR] |
| Full Idea: I'm tempted to say that mathematics is so rich that there are indefinitely many ways to prove anything - verbal/symbolic derivations and pictures are just two. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 9) | |
| A reaction: Brown has been defending pictures as a form of proof. I wonder how long his list would be, if we challenged him to give more details? Some people have very low standards of proof. |
| 9647 | Computers played an essential role in proving the four-colour theorem of maps [Brown,JR] |
| Full Idea: The celebrity of the famous proof in 1976 of the four-colour theorem of maps is that a computer played an essential role in the proof. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch.10) | |
| A reaction: The problem concerns the reliability of the computers, but then all the people who check a traditional proof might also be unreliable. Quis custodet custodies? |
| 9643 | Set theory may represent all of mathematics, without actually being mathematics [Brown,JR] |
| Full Idea: Maybe all of mathematics can be represented in set theory, but we should not think that mathematics is set theory. Functions can be represented as order pairs, but perhaps that is not what functions really are. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 7) | |
| A reaction: This seems to me to be the correct view of the situation. If 2 is represented as {φ,{φ}}, why is that asymmetrical? The first digit seems to be the senior and original partner, but how could the digits of 2 differ from one another? |
| 9644 | When graphs are defined set-theoretically, that won't cover unlabelled graphs [Brown,JR] |
| Full Idea: The basic definition of a graph can be given in set-theoretic terms,...but then what could an unlabelled graph be? | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 7) | |
| A reaction: An unlabelled graph will at least need a verbal description for it to have any significance at all. My daily mood-swings look like this.... |
| 9625 | To see a structure in something, we must already have the idea of the structure [Brown,JR] |
| Full Idea: Epistemology is a big worry for structuralists. ..To conjecture that something has a particular structure, we must already have conceived of the idea of the structure itself; we cannot be discovering structures by conjecturing them. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 4) | |
| A reaction: This has to be a crucial area of discussion. Do we have our heads full of abstract structures before we look out of the window? Externalism about the mind is important here; mind and world are not utterly distinct things. |
| 9628 | Sets seem basic to mathematics, but they don't suit structuralism [Brown,JR] |
| Full Idea: Set theory is at the very heart of mathematics; it may even be all there is to mathematics. The notion of set, however, seems quite contrary to the spirit of structuralism. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 4) | |
| A reaction: So much the worse for sets, I say. You can, for example, define ordinality in terms of sets, but that is no good if ordinality is basic to the nature of numbers, rather than a later addition. |
| 9606 | The irrationality of root-2 was achieved by intellect, not experience [Brown,JR] |
| Full Idea: We could not discover irrational numbers by physical measurement. The discovery of the irrationality of the square root of two was an intellectual achievement, not at all connected to sense experience. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 1) | |
| A reaction: Brown declares himself a platonist, and this is clearly a key argument for him, and rather a good one. Hm. I'll get back to you on this one... |
| 9612 | There is an infinity of mathematical objects, so they can't be physical [Brown,JR] |
| Full Idea: A simple argument makes it clear that all mathematical arguments are abstract: there are infinitely many numbers, but only a finite number of physical entities, so most mathematical objects are non-physical. The best assumption is that they all are. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 2) | |
| A reaction: This, it seems to me, is where constructivists score well (cf. Idea 9608). I don't have an infinity of bricks to build an infinity of houses, but I can imagine that the bricks just keep coming if I need them. Imagination is what is unbounded. |
| 9610 | Numbers are not abstracted from particulars, because each number is a particular [Brown,JR] |
| Full Idea: Numbers are not 'abstract' (in the old sense, of universals abstracted from particulars), since each of the integers is a unique individual, a particular, not a universal. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 2) | |
| A reaction: An interesting observation which I have not seen directly stated before. Compare Idea 645. I suspect that numbers should be thought of as higher-order abstractions, which don't behave like normal universals (i.e. they're not distributed). |
| 9620 | Empiricists base numbers on objects, Platonists base them on properties [Brown,JR] |
| Full Idea: Perhaps, instead of objects, numbers are associated with properties of objects. Basing them on objects is strongly empiricist and uses first-order logic, whereas the latter view is somewhat Platonistic, and uses second-order logic. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 4) | |
| A reaction: I don't seem to have a view on this. You can count tomatoes, or you can count red objects, or even 'instances of red'. Numbers refer to whatever can be individuated. No individuation, no arithmetic. (It's also Hume v Armstrong on laws on nature). |
| 9629 | For nomalists there are no numbers, only numerals [Brown,JR] |
| Full Idea: For the instinctive nominalist in mathematics, there are no numbers, only numerals. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 5) | |
| A reaction: Maybe. A numeral is a specific sign, sometimes in a specific natural language, so this seems to miss the fact that cardinality etc are features of reality, not just conventions. |
| 9639 | Does some mathematics depend entirely on notation? [Brown,JR] |
| Full Idea: Are there mathematical properties which can only be discovered using a particular notation? | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 6) | |
| A reaction: If so, this would seem to be a serious difficulty for platonists. Brown has just been exploring the mathematical theory of knots. |
| 9630 | The most brilliant formalist was Hilbert [Brown,JR] |
| Full Idea: In mathematics, the most brilliant formalist of all was Hilbert | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 5) | |
| A reaction: He seems to have developed his fully formalist views later in his career. See Mathematics|Basis of Mathematic|Formalism in our thematic section. Kreisel denies that Hilbert was a true formalist. |
| 9608 | There are no constructions for many highly desirable results in mathematics [Brown,JR] |
| Full Idea: Constuctivists link truth with constructive proof, but necessarily lack constructions for many highly desirable results of classical mathematics, making their account of mathematical truth rather implausible. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 2) | |
| A reaction: The tricky word here is 'desirable', which is an odd criterion for mathematical truth. Nevertheless this sounds like a good objection. How flexible might the concept of a 'construction' be? |
| 9645 | Constructivists say p has no value, if the value depends on Goldbach's Conjecture [Brown,JR] |
| Full Idea: If we define p as '3 if Goldbach's Conjecture is true' and '5 if Goldbach's Conjecture is false', it seems that p must be a prime number, but, amazingly, constructivists would not accept this without a proof of Goldbach's Conjecture. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 8) | |
| A reaction: A very similar argument structure to Schrödinger's Cat. This seems (as Brown implies) to be a devastating knock-down argument, but I'll keep an open mind for now. |
| 20901 | True Being only occurs when it is completely full, with atoms and no void [Democritus, by Aristotle] |
| Full Idea: In response to defenders of the One, Democritus says that what is, in the proper sense, is being that is completely full, but that such a being is not one, but that they are unlimited in number and invisible because of the smallness of their masses. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A007) by Aristotle - Coming-to-be and Passing-away (Gen/Corr) 325a28 | |
| A reaction: Democritus is in a tangle here. He says proper being has no void, having apparently conceded that motion needs void (which he admits is non-existent). So true being only occurs when everything grinds to a halt, which is not now. But Idea 20902. |
| 20902 | Being does not exist more than non-being [Democritus, by Aristotle] |
| Full Idea: They say that being does not exist more than non-being, because neither does the void exist more than the body. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A006) by Aristotle - Metaphysics 0985b09 | |
| A reaction: The claim that Being and Non-Being are the same thing is pretty startling. It seems to be an expedient to get Void into the picture, even though it is taken to be wholly devoid of qualities. |
| 20904 | The non-existent exists as much as the existent, because it has causal powers [Democritus] |
| Full Idea: What exists does not exist at all more than what does not exist, and both are causes in a similar way for the things that come about. | |
| From: Democritus (fragments/reports [c.431 BCE], A008), quoted by Simplicius - On Aristotle's 'Physics' p.28.4-27 | |
| A reaction: [Simplicius actually attributes this to the shadowy Leucippus] You can see the point. If you drive into a pothole, that has considerable causal powers. |
| 20903 | The only distinctions are Configuration (shape), Disposition (order) and Turning (position) [Democritus, by Aristotle] |
| Full Idea: They say that what is differs only by Configuration ([rhusmos], which is the shape), by Disposition ([diathege], which is the order), and by Turning ([tropê], which is the position. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A006) by Aristotle - Metaphysics 0985b16 | |
| A reaction: If you give the shape, structure and position of an object, there is no much more to say. Perhaps mention time. |
| 20893 | Nothing comes from non-existence, or passes into it [Democritus, by Diog. Laertius] |
| Full Idea: Nothing comes into being from what does not exist, nor is it destroyed into what does not exist. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A001) by Diogenes Laertius - Lives of Eminent Philosophers 09.44 | |
| A reaction: [part of a concise summary of Democritus by DL] Probably an intuition about conservation laws, rather than a speculation about the Big Bang. |
| 9619 | David's 'Napoleon' is about something concrete and something abstract [Brown,JR] |
| Full Idea: David's painting of Napoleon (on a white horse) is a 'picture' of Napoleon, and a 'symbol' of leadership, courage, adventure. It manages to be about something concrete and something abstract. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 3) | |
| A reaction: This strikes me as the germ of an extremely important idea - that abstraction is involved in our perception of the concrete, so that they are not two entirely separate realms. Seeing 'as' involves abstraction. |
| 20896 | It is not possible to know what sort each thing is [Democritus] |
| Full Idea: In reality [eteé] to recognise what sort each thing is, belongs to what is impracticable [aporos]. | |
| From: Democritus (fragments/reports [c.431 BCE], B008), quoted by Sextus Empiricus - Against the Logicians (two books) 7.137 | |
| A reaction: On the whole modern scientists (and the rest of us) shoehorn virtually everything into a specific category. It strikes me as wildly bad metaphysics to say that everything necessarily has its category. |
| 3357 | Democritus denies reality to large objects, because atomic entities can't combine to produce new ones [Benardete,JA on Democritus] |
| Full Idea: Democritus appears to rule out from his austere ontology all so-called emergent entities - even mountains and rivers - on the ground that two or more entities can never combine to produce a new one. | |
| From: comment on Democritus (fragments/reports [c.431 BCE]) by José A. Benardete - Metaphysics: the logical approach Ch.24 |
| 598 | Democritus said that substances could never be mixed, so atoms are the substances [Democritus, by Aristotle] |
| Full Idea: Democritus claimed that one substance could not be composed from two nor two from one; for him it is the atoms that are the substances. | |
| From: report of Democritus (fragments/reports [c.431 BCE]) by Aristotle - Metaphysics 1039a10 |
| 1532 | Sensible qualities can't be real if they appear different to different creatures [Democritus, by Theophrastus] |
| Full Idea: As proof of the fact that sensible qualities have no real existence he points to the fact that they do not appear the same to all creatures. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A135) by Theophrastus - On the Senses 63 |
| 20894 | Man is separated from reality [Democritus] |
| Full Idea: It is necessary to recognise that man by virtue of this criterion is separated from reality. | |
| From: Democritus (fragments/reports [c.431 BCE], B006), quoted by Sextus Empiricus - Against the Logicians (two books) 7.137 | |
| A reaction: I don't know what 'this criterion' is, but it strikes me as quite a good slogan for fans (like myself) of the representative theory of perception. Critics say it is the big objection to the representative theory, but I say 'get over it'. |
| 20897 | Obscure knowledge belongs to the five senses, and genuine knowledge is the other type [Democritus] |
| Full Idea: There are two forms of knowledge [gnomé], the one genuine, the other obscure. And to the obscure one belongs all of these: sight, hearing, smell, taste, touch. The other is genuine, and is separated from this one. | |
| From: Democritus (fragments/reports [c.431 BCE], B011), quoted by Sextus Empiricus - Against the Logicians (two books) 7.139 | |
| A reaction: [Sextus goes on to make it clear that the 'genuine' one is knowledge acquired by thought]. I take Parmenides to be the first rationalist. It is interesting that Democritus, who devoted his life to finding causal explanations, seems to be a rationalist. |
| 517 | All evidence comes from senses, so they are indispensable to the mind [Democritus] |
| Full Idea: Mind must never reject the senses, because that is where it gets its evidence, and it would be the mind's downfall. | |
| From: Democritus (fragments/reports [c.431 BCE], B125), quoted by Galen - On Medical Experience 15.8 |
| 577 | Democritus says there is either no truth, or it is concealed from us [Democritus, by Aristotle] |
| Full Idea: Democritus concludes that either there is no truth or it is concealed from us. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A112) by Aristotle - Metaphysics 1009b12 |
| 20895 | We actually know nothing, and opinions are mere flux [Democritus] |
| Full Idea: Certainly this argument too makes it clear that in reality [eteé] we know nothing about anything, but for each person opinion is a rhythmic afflux [epirhusmié]. | |
| From: Democritus (fragments/reports [c.431 BCE], B007), quoted by Sextus Empiricus - Against the Logicians (two books) 7.137 | |
| A reaction: This seems to pick 'all is flux' up from Heraclitus, and make Democritus (along with aspects of Socrates) the true source of ancient scepticism. |
| 1528 | We in fact know nothing, but we each restructure our reality with beliefs [Democritus] |
| Full Idea: In reality we know nothing about anything, but belief restructures things for each of us. | |
| From: Democritus (fragments/reports [c.431 BCE], B007), quoted by Sextus Empiricus - Against the Professors (six books) 7.136 |
| 492 | It is obviously impossible to understand the reality of each thing [Democritus] |
| Full Idea: It will be obvious that it is impossible to understand how in reality each thing is. | |
| From: Democritus (fragments/reports [c.431 BCE], B008), quoted by Sextus Empiricus - Against the Professors (six books) 7.137 |
| 515 | We know nothing in reality; for truth lies in an abyss [Democritus] |
| Full Idea: We know nothing in reality; for truth lies in an abyss. | |
| From: Democritus (fragments/reports [c.431 BCE], B117), quoted by Diogenes Laertius - Lives of Eminent Philosophers 09.72.10 |
| 20892 | Democritus was devoted to discovering causal explanations [Democritus, by Eusebius] |
| Full Idea: Democritus himself, as they say, stated that he would rather discover a single causal explanation [aitiologia] than become the King of the Persians. | |
| From: report of Democritus (fragments/reports [c.431 BCE], B118) by Eusebius - Preparation for the Gospel 14.27.4 | |
| A reaction: Democritus seems to be clearly the father of the physical sciences, because he focused single-mindedly on physical and causal explanations. David Lewis says all explanations are causal. |
| 5882 | Democritus says soul consists of smooth round bodies brought together in accidental collision [Democritus, by Cicero] |
| Full Idea: Since Democritus makes the soul consist of minute smooth round bodies brought together in some sort of accidental collision, let us pass him over. | |
| From: report of Democritus (fragments/reports [c.431 BCE]) by M. Tullius Cicero - Tusculan Disputations I.xi.23 | |
| A reaction: If we accept that Democritus thought the collision of atoms 'accidental', then it doesn't sound like a very good theory. What would Cicero say if we replaced 'accidental' with 'naturally selected'? |
| 6034 | Atomists say soul has a rational part in the chest, and a diffused non-rational part [Democritus, by Aetius] |
| Full Idea: Democritus and Epicurus say the soul has two parts, one which is rational and is situated in the chest area, and the other which is non-rational and is spread throughout the entire compound of the body. | |
| From: report of Democritus (fragments/reports [c.431 BCE]) by Aetius - fragments/reports 4.4.6 | |
| A reaction: The spread part corresponds to such things as feeling fear in the stomach, or excitement throughout the limbs. I can't think what grounds there would be for choosing the chest as the home of reason. I suppose you can hear reason thumping in there.. |
| 20912 | The soul is the same as the mind [Democritus, by Aristotle] |
| Full Idea: Democritus says the soul is the same thing as the mind. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A101) by Aristotle - De Anima 405a10 | |
| A reaction: This is not in contrast to the Christian concept of the soul, but in contrast to the normal view of psuché, which is more like the life that permeates the whole body. Democritus was more in tune than Aristotle with modern thought on this. |
| 20916 | Animals have a share of reason [Democritus, by Porphyry] |
| Full Idea: Democritus recognised that animals have a share of reason. | |
| From: report of Democritus (fragments/reports [c.431 BCE]) by Porphyry - On Abstinence 3.6.7 | |
| A reaction: Since he considers thinking to be the interaction of atoms in the body, which animals evidently possess, this seems consistent. No one seems to observed animals closely before the 20th century, other than to exploit them. |
| 20914 | The directive centre is located in the whole head [Democritus, by Ps-Plutarch] |
| Full Idea: Democritus says [the directive centre is located] in the whole head. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A105) by Pseudo-Plutarch - On the Doctrine of the Philosophers 4.5.1 | |
| A reaction: The whole head is not quite the brain, but he is getting very warm indeed, and long before anyone else got so close. |
| 6033 | Democritus said everything happens of necessity, by natural motion of atoms [Democritus, by Cicero] |
| Full Idea: Democritus, the founder of atomism, preferred to accept that all things happened by necessity than to tear from the atomic bodies their natural motions. | |
| From: report of Democritus (fragments/reports [c.431 BCE]) by M. Tullius Cicero - On Fate ('De fato') §22 | |
| A reaction: This is in opposition to Epicurus, who said that atoms can have a 'swerve', making free will possible. It is suggested that Epicurus was the first to really grasp the problem of free will. Democritus was just stating the (to him) obvious. |
| 5088 | Some say there is a determinate cause for every apparently spontaneous event [Democritus, by Aristotle] |
| Full Idea: Some people (Democritus?) say there is no such thing as a chance event; they claim that there is always a determinate cause for everything which is said to be a chance or a spontaneous event. | |
| From: report of Democritus (fragments/reports [c.431 BCE]) by Aristotle - Physics 195b37 | |
| A reaction: This is the mutual implication of physicalism and determinism, which strikes me as unavoidable. I say: don't panic about morality because determinism is true. Embrace determinism - it is harmless and true. Its opposite is a nonsense. |
| 21670 | Democritus said atoms only move by their natural motions, which are therefore necessary [Democritus, by Cicero] |
| Full Idea: The author of the atomic theory, Democritus, preferred to accept the view that all events are caused by necessity, rather than to deprive the atoms of their natural motions. | |
| From: report of Democritus (fragments/reports [c.431 BCE]) by M. Tullius Cicero - On Fate ('De fato') 10.23 | |
| A reaction: The 'deprivation' would have to be caused by mind, or by the later 'swerve' of Epicurus. |
| 20913 | Democritus says the soul is the body, and thinking is thus the mixture of the body [Democritus, by Theophrastus] |
| Full Idea: Democritus explains thinking by the mixture of the body, which is surely in accordance with his reasoning, since he makes the soul the body. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A135) by Theophrastus - On the Senses 58 | |
| A reaction: I agree with Democritus. |
| 24041 | Democritus says spherical atoms are fire, and constitute the soul [psuche] [Democritus, by Aristotle] |
| Full Idea: Democritus says the soul is a sort of fire. For the shapes and atoms are unlimitied and those that are spherical he says are fire and soul - which are like the motes in the air when sunbeams come through the window. | |
| From: report of Democritus (fragments/reports [c.431 BCE], DK 67-68) by Aristotle - De Anima 403b31 | |
| A reaction: It's hard to see why the spherical atoms should be fire. Maybe because they move together quickly and easily. …At 404a5 Aristotle agrees with me! |
| 9611 | 'Abstract' nowadays means outside space and time, not concrete, not physical [Brown,JR] |
| Full Idea: The current usage of 'abstract' simply means outside space and time, not concrete, not physical. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 2) | |
| A reaction: This is in contrast to Idea 9609 (the older notion of being abstracted). It seems odd that our ancestors had a theory about where such ideas came from, but modern thinkers have no theory at all. Blame Frege for that. |
| 9609 | The older sense of 'abstract' is where 'redness' or 'group' is abstracted from particulars [Brown,JR] |
| Full Idea: The older sense of 'abstract' applies to universals, where a universal like 'redness' is abstracted from red particulars; it is the one associated with the many. In mathematics, the notion of 'group' or 'vector space' perhaps fits this pattern. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 2) | |
| A reaction: I am currently investigating whether this 'older' concept is in fact dead. It seems to me that it is needed, as part of cognitive science, and as the crucial link between a materialist metaphysic and the world of ideas. |
| 9640 | A term can have not only a sense and a reference, but also a 'computational role' [Brown,JR] |
| Full Idea: In addition to the sense and reference of term, there is the 'computational' role. The name '2' has a sense (successor of 1) and a reference (the number 2). But the word 'two' has little computational power, Roman 'II' is better, and '2' is a marvel. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 6) | |
| A reaction: Very interesting, and the point might transfer to natural languages. Synonymous terms carry with them not just different expressive powers, but the capacity to play different roles (e.g. slang and formal terms, gob and mouth). |
| 1540 | Pleasure and pain guide our choices of good and bad [Democritus] |
| Full Idea: The guides to what is good and bad for people are pleasure and pain. | |
| From: Democritus (fragments/reports [c.431 BCE], B188), quoted by John Stobaeus - Anthology 3.01.46 |
| 495 | Wisdom creates a healthy passion-free soul [Democritus] |
| Full Idea: Medicine heals diseases of the body, wisdom frees the soul from passions. | |
| From: Democritus (fragments/reports [c.431 BCE], B031), quoted by Clement - Pedagogue 1.6.2.1 | |
| A reaction: The interesting concept of a healthy mind seems to have got lost in modern moral philosophy. |
| 1537 | Happiness is identifying and separating the pleasures [Democritus, by Stobaeus] |
| Full Idea: Democritus thinks that happiness consists in the determination and separation of pleasures, and that this is what is both finest and most beneficial for people. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A167) by John Stobaeus - Anthology 2.07.3 | |
| A reaction: A great deal of the strategy and ethics of living consists (if you are lucky) of discriminating among possible pleasures. Philosophers should produce criteria. |
| 20917 | Contentment comes from moderation and proportion in life [Democritus, by Stobaeus] |
| Full Idea: Contentment [euthumia] comes about for human beings from the moderation of enjoyment and proportion [summetria] in life. | |
| From: report of Democritus (fragments/reports [c.431 BCE], B191) by John Stobaeus - Anthology 3.1.210 | |
| A reaction: This is close to Aristotle's doctrine of the Mean. The majority of ethical ideas attributed to Democritus (presumably by the Epicureans) are thought to be spurious. This idea actually sounds rather stoic. |
| 13551 | Democritus says wealth is a burden to the virtuous mind [Democritus, by Seneca] |
| Full Idea: Democritus rejected wealth, regarding it as a burden to the virtuous mind. | |
| From: report of Democritus (fragments/reports [c.431 BCE]) by Seneca the Younger - On Providence §6 | |
| A reaction: The rival view is that wealth empowers a virtuous person to perform more fine deeds. Democritus seems to have a rather solitary view of virtue. |
| 13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
| Full Idea: In a single day there lies open to men of learning more than there ever does to the unenlightened in the longest of lifetimes. | |
| From: Posidonius (fragments/reports [c.95 BCE]), quoted by Seneca the Younger - Letters from a Stoic 078 | |
| A reaction: These remarks endorsing the infinite superiority of the educated to the uneducated seem to have been popular in late antiquity. It tends to be the religions which discourage great learning, especially in their emphasis on a single book. |
| 9635 | Given atomism at one end, and a finite universe at the other, there are no physical infinities [Brown,JR] |
| Full Idea: There seem to be no actual infinites in the physical realm. Given the correctness of atomism, there are no infinitely small things, no infinite divisibility. And General Relativity says that the universe is only finitely large. | |
| From: James Robert Brown (Philosophy of Mathematics [1999], Ch. 5) | |
| A reaction: If time was infinite, you could travel round in a circle forever. An atom has size, so it has a left, middle and right to it. Etc. They seem to be physical, so we will count those too. |
| 493 | Experiences are merely convention; only atoms and the void are real [Democritus] |
| Full Idea: Sweet exists by convention, bitter by convention, colour by convention; atoms and void alone exist in reality. | |
| From: Democritus (fragments/reports [c.431 BCE], B009), quoted by Sextus Empiricus - Against the Logicians (two books) 7.135 |
| 17542 | 'Full' and 'Void' secularised Parmenides's Being and Not-being [Democritus, by Heisenberg] |
| Full Idea: In atomism, the antithesis of Being and Not-being of Parmenides is secularised into the antithesis of the 'Full' and the 'Void'. | |
| From: report of Democritus (fragments/reports [c.431 BCE]) by Werner Heisenberg - Physics and Philosophy 04 |
| 5947 | If only atoms are real and the rest is convention, we wouldn't bother to avoid pain [Democritus, by Diogenes of Oen.] |
| Full Idea: Democritus erred when he said that the atoms alone exist in truth among realities, but everything else is convention; for then, far from discovering the truth, we shall not even be able to live, since we shall avoid neither fire nor wounds. | |
| From: report of Democritus (fragments/reports [c.431 BCE]) by Diogenes (Oen) - fragments/reports F2 7 | |
| A reaction: The point is that we have to treat pain as a reality, not just as a convention. I suspect that Diogenes is making the same mistake made by modern attackers of 'eliminativism'. It is all about identity and reduction and levels of reality… |
| 13219 | When atoms touch, why don't they coalesce, like water drops? [Aristotle on Democritus] |
| Full Idea: Why, when they come into contact, do they [atoms] not coalesce into one, as drops of water run together when drop touches drop? | |
| From: comment on Democritus (fragments/reports [c.431 BCE]) by Aristotle - Coming-to-be and Passing-away (Gen/Corr) 326a33 | |
| A reaction: Presumably we must think of atoms as having basic ontological unity, rather than as being little globules of 'stuff'. They are more like monads than they are like mud. |
| 1533 | Because appearance is infinitely varied, atomists assume infinitely many shapes of atom [Democritus, by Aristotle] |
| Full Idea: They thought that truth lay in appearances, which they appreciated are contradictory and infinite, so they made the shapes of atoms infinite. Thus the infinite changes in compounds create the infinitely varies appearances. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A009) by Aristotle - Coming-to-be and Passing-away (Gen/Corr) 315b9 |
| 20899 | Atoms cling together, until a stronger necessity disperses them [Democritus, by Aristotle] |
| Full Idea: Democritus thinks that the substances hold on to one another and remain together for a length of time until some stronger necessity arising from their surroundings shakes and disperses them. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A037) by Aristotle - On Democritus (frag) | |
| A reaction: [quoted in Simplicius, Commentary on Aristotle's On the Heavens] He's not wrong. This seems to provide a mechanism for the Heracltean flux. Ancient critics wanted to know where the 'stronger necessity' came from. |
| 20898 | Atoms are irregular, hooked, concave, convex, and many other shapes [Democritus, by Aristotle] |
| Full Idea: Some substances are irregular, others hook-shaped, other concave, other convex, others provided with innumerable other differences. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A037) by Aristotle - On Democritus (frag) | |
| A reaction: [quoted in Simplicius, Commentary on Aristotle's On the Heavens] 'Substance' here means a fundamental object, which for Democritus is an undividable atom. |
| 20908 | There could be an atom the size of the world [Democritus, by Ps-Plutarch] |
| Full Idea: Democritus say that it is possible that there exists an atom of the size of the world. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A047) by Pseudo-Plutarch - On the Doctrine of the Philosophers 1.12.6 | |
| A reaction: The editor says this may have been a criticism of Democritus - presumably a reductio ad absurdum. But Democritus has no upper limit on the size of an atom. It challenges the imagination to treat such a huge thing as indivisible. |
| 1527 | There must be atoms, to avoid the absurdity of infinite division down to nothing [Democritus, by Aristotle] |
| Full Idea: If everything is infinitely divided, what survives the divisions? Alternatively, division would end at points with no magnitude, in which case bodies are composed of nothing. This is the argument claiming there are atoms of some magnitude. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A048b) by Aristotle - Coming-to-be and Passing-away (Gen/Corr) 316a14- |
| 20909 | The basic atoms are without qualities - which only arise from encounters between atoms [Democritus, by Galen] |
| Full Idea: Democritus and the Epicureans posit that the first element is without quality, possessing by nature neither whiteness, blackness, sweetness or bitterness, warmth or cold. ...It is from the encounter of the atoms that all the sensible qualities come about. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A049) by Galen - On Hippocrates and Plato 1.2 | |
| A reaction: Idea 493 comes in the middle of this summary by Galen. Hence atoms play the role that substrates play in object-based metaphysics. So atoms have the same problem. Is the shape of an atom a quality of an atom. Or are qualities what atoms DO? |
| 1536 | If a cone is horizontally sliced the surfaces can't be equal, so it goes up in steps [Democritus] |
| Full Idea: If a cone is cut parallel to the base are the two new surfaces equal or unequal? If they are unequal, the cone must have gone up in steps. If they are equal then the cone must have been a cylinder, which is absurd. | |
| From: Democritus (fragments/reports [c.431 BCE], B155), quoted by Plutarch - 72: Against Stoics on common Conceptions 1079e1 |
| 1525 | Atomists say there are only three differences - in shape, arrangement and position [Democritus, by Aristotle] |
| Full Idea: Democritus and Leucippus say that there are only three differences - in shape, arrangement and position. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A006) by Aristotle - Metaphysics 0985b15 |
| 23314 | Greeks explained regularity by intellectual design, not by laws [Democritus, by Frede,M] |
| Full Idea: It is clear that Democritus had no idea of laws of nature …for in Greek thought regularity of behaviour is associated with design by an intellect. | |
| From: report of Democritus (fragments/reports [c.431 BCE]) by Michael Frede - A Free Will Intro | |
| A reaction: Ah. A simple realisation…! Seventeenth century laws of nature offered an explanation of natural order which didn't rely on God. Even though those scientists were all theists. |
| 24059 | Democritus is wrong: in a void we wouldn't see a distant ant in exact detail [Aristotle on Democritus] |
| Full Idea: Democritus did not speak correctly in supposing that if the intermediate space became a void, we would see an ant in exact detail if it were up in the heaven. …If the intermediate space became a void, rather nothing would be seen at all. | |
| From: comment on Democritus (fragments/reports [c.431 BCE]) by Aristotle - De Anima 419a15 | |
| A reaction: Depends what you mean by void, but Aristotle is nearer the truth. Is vision clearer in outer space than in our higher atmosphere? |
| 5101 | Movement is impossible in a void, because nothing can decide the direction of movement [Aristotle on Democritus] |
| Full Idea: Void makes it impossible for anything to move, since in a void there is nowhere for a thing to move to more or less than anywhere else, because the void by definition contains no differentiation. | |
| From: comment on Democritus (fragments/reports [c.431 BCE]) by Aristotle - Physics 214b32 | |
| A reaction: A lovely application of the Principle of Sufficient Reason. However this assumes that the cause of the movement is going to be in the void (telos?), rather than in the body which will move (modern causation?). |
| 20905 | Growth and movement would not exist if there were no void to receive them [Democritus] |
| Full Idea: They say that one argument for void is that otherwise local motion (that is, locomotion and growth) would not exist: for there would not seem to be motion if there were no void, for what is full is incapable of receiving anything. | |
| From: Democritus (fragments/reports [c.431 BCE], A019), quoted by Aristotle - Physics 213b03 | |
| A reaction: The modern concept of a 'field' seems to have removed the possibility of a genuine 'void'. |
| 20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |
| Full Idea: Posidonius defined time thus: it is an interval of motion, or the measure of speed and slowness. | |
| From: report of Posidonius (fragments/reports [c.95 BCE]) by John Stobaeus - Anthology 1.08.42 | |
| A reaction: Hm. Can we define motion or speed without alluding to time? Looks like we have to define them as a conjoined pair, which means we cannot fully understand either of them. |
| 20911 | There are unlimited worlds of varying sizes, some without life or water [Democritus, by Hippolytus] |
| Full Idea: Democritus says that there exist unlimited worlds and that they are different in magnitude. ...Some worlds are devoid of animals and plants and of all humidity. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A010, A040) by Hippolytus - Refutation of All Heresies 1.12,13.2-4 | |
| A reaction: I'm not clear why Democritus came up with the idea of the Multicosmos. I don't suppose he meant the moon or planets, but another Cosmos. |
| 1535 | Democritus said people imagined gods as the source of what awed or frightened them [Democritus, by Sext.Empiricus] |
| Full Idea: Democritus thought that people imagined gods as responsible for the frightening and awesome things that happen in this world. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A075) by Sextus Empiricus - Against the Professors (six books) 9.24 |
| 20915 | The soul is destroyed with the body [Democritus, by Ps-Plutarch] |
| Full Idea: Democritus says the soul is destructible, and is destroyed together with the whole body. | |
| From: report of Democritus (fragments/reports [c.431 BCE], A109) by Pseudo-Plutarch - On the Doctrine of the Philosophers 4.7.4 | |
| A reaction: This is the only belief possible for Democritus, since everything, including life and soul, is just the confluence of atoms, and they are regularly dispersed. This is the epitome of materialist philosophy. |