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All the ideas for 'Structures and Structuralism in Phil of Maths', 'Letter to Herodotus' and 'Intensions Revisited'

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49 ideas

1. Philosophy / F. Analytic Philosophy / 5. Linguistic Analysis
If we are to use words in enquiry, we need their main, unambiguous and uncontested meanings [Epicurus]
     Full Idea: It is necessary that we look to the primary conception corresponding to each word and that it stand in no need of demonstration, if, that is, we are going to have something to which we can refer the object of search or puzzlement and opinion.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 38)
     A reaction: This either points to definition or to consensus, and since definition seems in danger of some sort of Quinean circularity, I favour consensus. Philosophy is, after all, people discussing things, not inscriptions sent to the gods.
3. Truth / A. Truth Problems / 8. Subjective Truth
Observation and applied thought are always true [Epicurus]
     Full Idea: Everything that is observed or grasped by the intellect in an act of application is true.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 62)
     A reaction: Not quite clear what he means, but Epicurus is committed to perception as the source of knowledge, with the intellect extending the findings of the senses. He might subscribe to Descartes's 'clear and distinct' perceptions.
3. Truth / F. Semantic Truth / 2. Semantic Truth
While true-in-a-model seems relative, true-in-all-models seems not to be [Reck/Price]
     Full Idea: While truth can be defined in a relative way, as truth in one particular model, a non-relative notion of truth is implied, as truth in all models.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: [The article is actually discussing arithmetic] This idea strikes me as extremely important. True-in-all-models is usually taken to be tautological, but it does seem to give a more universal notion of truth. See semantic truth, Tarski, Davidson etc etc.
4. Formal Logic / D. Modal Logic ML / 1. Modal Logic
Quantified modal logic collapses if essence is withdrawn [Quine]
     Full Idea: The whole of quantified modal logic collapses if essence is withdrawn.
     From: Willard Quine (Intensions Revisited [1977], p.121)
     A reaction: Quine offers an interesting qualification to this crushing remark in Idea 13590. The point is that objects must retain their identity in modal contexts, as if I say 'John Kennedy might have been Richard Nixon'. What could that mean?
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
ZFC set theory has only 'pure' sets, without 'urelements' [Reck/Price]
     Full Idea: In standard ZFC ('Zermelo-Fraenkel with Choice') set theory we deal merely with pure sets, not with additional urelements.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §2)
     A reaction: The 'urelements' would the actual objects that are members of the sets, be they physical or abstract. This idea is crucial to understanding philosophy of mathematics, and especially logicism. Must the sets exist, just as the urelements do?
5. Theory of Logic / G. Quantification / 5. Second-Order Quantification
Three types of variable in second-order logic, for objects, functions, and predicates/sets [Reck/Price]
     Full Idea: In second-order logic there are three kinds of variables, for objects, for functions, and for predicates or sets.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: It is interesting that a predicate seems to be the same as a set, which begs rather a lot of questions. For those who dislike second-order logic, there seems nothing instrinsically wicked in having variables ranging over innumerable multi-order types.
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
'Analysis' is the theory of the real numbers [Reck/Price]
     Full Idea: 'Analysis' is the theory of the real numbers.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §2)
     A reaction: 'Analysis' began with the infinitesimal calculus, which later built on the concept of 'limit'. A continuum of numbers seems to be required to make that work.
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / a. Axioms for numbers
Mereological arithmetic needs infinite objects, and function definitions [Reck/Price]
     Full Idea: The difficulties for a nominalistic mereological approach to arithmetic is that an infinity of physical objects are needed (space-time points? strokes?), and it must define functions, such as 'successor'.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: Many ontologically austere accounts of arithmetic are faced with the problem of infinity. The obvious non-platonist response seems to be a modal or if-then approach. To postulate infinite abstract or physical entities so that we can add 3 and 2 is mad.
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / e. Peano arithmetic 2nd-order
Peano Arithmetic can have three second-order axioms, plus '1' and 'successor' [Reck/Price]
     Full Idea: A common formulation of Peano Arithmetic uses 2nd-order logic, the constant '1', and a one-place function 's' ('successor'). Three axioms then give '1 is not a successor', 'different numbers have different successors', and induction.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §2)
     A reaction: This is 'second-order' Peano Arithmetic, though it is at least as common to formulate in first-order terms (only quantifying over objects, not over properties - as is done here in the induction axiom). I like the use of '1' as basic instead of '0'!
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
Set-theory gives a unified and an explicit basis for mathematics [Reck/Price]
     Full Idea: The merits of basing an account of mathematics on set theory are that it allows for a comprehensive unified treatment of many otherwise separate branches of mathematics, and that all assumption, including existence, are explicit in the axioms.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: I am forming the impression that set-theory provides one rather good model (maybe the best available) for mathematics, but that doesn't mean that mathematics is set-theory. The best map of a landscape isn't a landscape.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / a. Structuralism
Structuralism emerged from abstract algebra, axioms, and set theory and its structures [Reck/Price]
     Full Idea: Structuralism has emerged from the development of abstract algebra (such as group theory), the creation of axiom systems, the introduction of set theory, and Bourbaki's encyclopaedic survey of set theoretic structures.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §2)
     A reaction: In other words, mathematics has gradually risen from one level of abstraction to the next, so that mathematical entities like points and numbers receive less and less attention, with relationships becoming more prominent.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / b. Varieties of structuralism
Relativist Structuralism just stipulates one successful model as its arithmetic [Reck/Price]
     Full Idea: Relativist Structuralism simply picks one particular model of axiomatised arithmetic (i.e. one particular interpretation that satisfies the axioms), and then stipulates what the elements, functions and quantifiers refer to.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: The point is that a successful model can be offered, and it doesn't matter which one, like having any sort of aeroplane, as long as it flies. I don't find this approach congenial, though having a model is good. What is the essence of flight?
There are 'particular' structures, and 'universal' structures (what the former have in common) [Reck/Price]
     Full Idea: The term 'structure' has two uses in the literature, what can be called 'particular structures' (which are particular relational systems), but also what can be called 'universal structures' - what particular systems share, or what they instantiate.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §6)
     A reaction: This is a very helpful distinction, because it clarifies why (rather to my surprise) some structuralists turn out to be platonists in a new guise. Personal my interest in structuralism has been anti-platonist from the start.
Pattern Structuralism studies what isomorphic arithmetic models have in common [Reck/Price]
     Full Idea: According to 'pattern' structuralism, what we study are not the various particular isomorphic models of arithmetic, but something in addition to them: a corresponding pattern.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §7)
     A reaction: Put like that, we have to feel a temptation to wield Ockham's Razor. It's bad enough trying to give the structure of all the isomorphic models, without seeking an even more abstract account of underlying patterns. But patterns connect to minds..
There are Formalist, Relativist, Universalist and Pattern structuralism [Reck/Price]
     Full Idea: There are four main variants of structuralism in the philosophy of mathematics - formalist structuralism, relativist structuralism, universalist structuralism (with modal variants), and pattern structuralism.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §9)
     A reaction: I'm not sure where Chihara's later book fits into this, though it is at the nominalist end of the spectrum. Shapiro and Resnik do patterns (the latter more loosely); Hellman does modal universalism; Quine does the relativist version. Dedekind?
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / c. Nominalist structuralism
Formalist Structuralism says the ontology is vacuous, or formal, or inference relations [Reck/Price]
     Full Idea: Formalist Structuralism endorses structural methodology in mathematics, but rejects semantic and metaphysical problems as either meaningless, or purely formal, or as inference relations.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §3)
     A reaction: [very compressed] I find the third option fairly congenial, certainly in preference to rather platonist accounts of structuralism. One still needs to distinguish the mathematical from the non-mathematical in the inference relations.
Maybe we should talk of an infinity of 'possible' objects, to avoid arithmetic being vacuous [Reck/Price]
     Full Idea: It is tempting to take a modal turn, and quantify over all possible objects, because if there are only a finite number of actual objects, then there are no models (of the right sort) for Peano Arithmetic, and arithmetic is vacuously true.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: [compressed; Geoffrey Hellman is the chief champion of this view] The article asks whether we are not still left with the puzzle of whether infinitely many objects are possible, instead of existent.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / d. Platonist structuralism
Universalist Structuralism is based on generalised if-then claims, not one particular model [Reck/Price]
     Full Idea: Universalist Structuralism is a semantic thesis, that an arithmetical statement asserts a universal if-then statement. We build an if-then statement (using quantifiers) into the structure, and we generalise away from any one particular model.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: There remains the question of what is distinctively mathematical about the highly generalised network of inferences that is being described. Presumable the axioms capture that, but why those particular axioms? Russell is cited as an originator.
Universalist Structuralism eliminates the base element, as a variable, which is then quantified out [Reck/Price]
     Full Idea: Universalist Structuralism is eliminativist about abstract objects, in a distinctive form. Instead of treating the base element (say '1') as an ambiguous referring expression (the Relativist approach), it is a variable which is quantified out.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §5)
     A reaction: I am a temperamental eliminativist on this front (and most others) so this is tempting. I am also in love with the concept of a 'variable', which I take to be utterly fundamental to all conceptual thought, even in animals, and not just a trick of algebra.
6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / e. Structuralism critique
The existence of an infinite set is assumed by Relativist Structuralism [Reck/Price]
     Full Idea: Relativist Structuralism must first assume the existence of an infinite set, otherwise there would be no model to pick, and arithmetical terms would have no reference.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: See Idea 10169 for Relativist Structuralism. They point out that ZFC has an Axiom of Infinity.
7. Existence / A. Nature of Existence / 1. Nature of Existence
Nothing comes to be from what doesn't exist [Epicurus]
     Full Idea: Nothing comes into being from what is not.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 38)
     A reaction: King Lear puts it better: Nothing will come of nothing [1.i]. There seems to be an underlying assumption that coming into being out of nothing is much weirder than just existing, but I am not convinced about that. It's all equally weird.
If disappearing things went to nothingness, nothing could return, and it would all be gone by now [Epicurus]
     Full Idea: If that which disappears were destroyed into what is not, all things would have been destroyed, since that into which they were dissolved does not exist.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 39)
     A reaction: This follows on from Idea 14028. Theologians will immediately spot that this is the underlying principle cited by Aquinas in his Third Way for proving God's existence (Idea 1431).
7. Existence / B. Change in Existence / 1. Nature of Change
The totality is complete, so there is no room for it to change, and nothing extraneous to change it [Epicurus]
     Full Idea: The totality of things has always been just like it is now and always will be. For there is nothing for it to change into. For there exists nothing in addition to the totality, which could enter into it and produce the change.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 39)
     A reaction: This smacks of the sort of dubious arguments that the medieval theologians fell in love with. I never thought I'd say this, but I think Epicurus needs a comprehensive course in set theory before he makes remarks like this.
7. Existence / D. Theories of Reality / 6. Physicalism
Astronomical movements are blessed, but they don't need the help of the gods [Epicurus]
     Full Idea: Movements, turnings, risings, settings, and related phenomena occur without any god helping out and ordaining or being about to ordain things, and at the same time have complete blessedness and indestructibility.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 76)
     A reaction: Epicurus is sometimes accused of atheism for remarks like these, but he is always trying to show piety in his attitudes. We might now call this attitude 'deism' (see alphabetical themes).
8. Modes of Existence / B. Properties / 8. Properties as Modes
The perceived accidental properties of bodies cannot be conceived of as independent natures [Epicurus]
     Full Idea: The shapes, colours, sizes and weights which are predicated of body as accidents, ...and are known by sense-perception, must not be thought of as independent natures (for that is inconceivable).
     From: Epicurus (Letter to Herodotus [c.293 BCE], 68)
     A reaction: I take this to be an anti-platonist remark, though he is not denying that the accidental properties may have some universal character. I'm struck by how close the basic metaphysics of Epicurus is to that of Aristotle.
Accidental properties give a body its nature, but are not themselves bodies or parts of bodies [Epicurus]
     Full Idea: Accidental qualities are not non-existent, nor are they distinct corporeal entities inhering in the body, nor parts of it. We should think that the whole body throughout derives its permanent nature from these properties, though not as a compound of them.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 69)
     A reaction: 'Permanent' nature sounds more like essential than accidental properties. This is uncomfortably negative in its attempt to pin down what accidental properties are. The last bit seems to deny the bundle view of objects. Would he like tropes?
8. Modes of Existence / E. Nominalism / 6. Mereological Nominalism
A nominalist might avoid abstract objects by just appealing to mereological sums [Reck/Price]
     Full Idea: One way for a nominalist to reject appeal to all abstract objects, including sets, is to only appeal to nominalistically acceptable objects, including mereological sums.
     From: E Reck / M Price (Structures and Structuralism in Phil of Maths [2000], §4)
     A reaction: I'm suddenly thinking that this looks very interesting and might be the way to go. The issue seems to be whether mereological sums should be seen as constrained by nature, or whether they are unrestricted. See Mereology in Ontology...|Intrinsic Identity.
9. Objects / B. Unity of Objects / 1. Unifying an Object / b. Unifying aggregates
A 'body' is a conception of an aggregate, with properties defined by application conditions [Epicurus]
     Full Idea: Properties are known by their peculiar forms of application and comprehension, in close accompaniment with the aggregate [of atoms], which is given the predicate 'body' by reference to the aggregate conception.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 69)
     A reaction: There is an interesting hint here of how to think of properties (as both applying and comprehended in some distinctive way), and a suggestion that there is something conventional about bodies, depending on how we conceive them.
9. Objects / D. Essence of Objects / 9. Essence and Properties
Bodies have impermanent properties, and permanent ones which define its conceived nature [Epicurus]
     Full Idea: Impermanent properties do not have the nature of an entire thing, which we call a body when we grasp it in aggregate, nor the nature of permanent accompaniments without which it is not possible to conceive of a body.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 70)
     A reaction: Epicurus doesn't discuss essences, but this seems to commit to the basic Aristotelian idea, that there there are some properties which actually bestow identity, and then others which are optional for that thing. The 'conception' is always mentioned.
9. Objects / D. Essence of Objects / 15. Against Essentialism
Essences can make sense in a particular context or enquiry, as the most basic predicates [Quine]
     Full Idea: The notion of essence makes sense in context. Relative to a particular enquiry, some predicates may play a more basic role than others, or may apply more fixedly; and these may be treated as essential.
     From: Willard Quine (Intensions Revisited [1977], p.121)
     A reaction: Quine has got a bad press on essentialism, and on modal logic, but I take this point seriously. If you give something a fixed identity by means of essence in some context, you can then go ahead and apply possible world reasoning in that context.
10. Modality / A. Necessity / 11. Denial of Necessity
Necessity is relative to context; it is what is assumed in an inquiry [Quine]
     Full Idea: The very notion of necessity makes sense to me only relative to context. Typically it is applied to what is assumed in an inquiry, as against what has yet to transpire.
     From: Willard Quine (Intensions Revisited [1977], p.121)
     A reaction: Lots of things are assumed by an inquiry without an assumption that they must be true. Quine is the greatest opponent of necessity in all of philosophy. Asserting necessities, though, is too much fun to give up. It would ruin philosophy.
10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / c. Possible but inconceivable
Above and below us will never appear to be the same, because it is inconceivable [Epicurus]
     Full Idea: What is over our heads ...or what is below any point which we think of ...will never appear to us as being at the same time and in the same respect both up and down. For it is impossible to conceive of this.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 60)
     A reaction: Note that he says it will 'never appear to us' as both - not that it absolutely cannot be both. Both Aristotle and Epicurus are much more focused on how our humanity shapes our metaphysics than the modern pure metaphysicians are.
10. Modality / E. Possible worlds / 1. Possible Worlds / e. Against possible worlds
Possible worlds are a way to dramatise essentialism, and yet they presuppose essentialism [Quine]
     Full Idea: Talk of possible worlds is a graphic way of waging the essentialist philosophy, but it is only that; it is not an explication. Essence is needed to identify an object from one possible world to another.
     From: Willard Quine (Intensions Revisited [1977], p.118)
     A reaction: He makes the proposal sound circular, but I take a commitment to essences to be prior to talk of possible worlds. Possible worlds are a tool for clarifying modalities, not for clarifying essential identities.
10. Modality / E. Possible worlds / 3. Transworld Objects / b. Rigid designation
A rigid designator (for all possible worlds) picks out an object by its essential traits [Quine]
     Full Idea: A rigid designator differs from others in that it picks out its object by essential traits. It designates the object in all possible worlds in which it exists.
     From: Willard Quine (Intensions Revisited [1977], p.118)
     A reaction: This states the point more clearly than Kripke ever does, and I presume it is right. Thus when we say that we wish 'our' Hubert Humphrey had won the election, we can allow that his victory elation would change him a bit. Kripke is right.
11. Knowledge Aims / A. Knowledge / 4. Belief / a. Beliefs
Beliefs can be ascribed to machines [Quine]
     Full Idea: Beliefs have been ascribed to machines, in support of a mechanistic philosophy, and I share this attitude.
     From: Willard Quine (Intensions Revisited [1977], p.123)
     A reaction: [He cites Raymond Nelson] One suspects that this is Quine's latent behaviourism speaking. It strikes me as a crass misuse of 'belief' to ascribe it to a simple machine like a thermostat.
11. Knowledge Aims / A. Knowledge / 4. Belief / c. Aim of beliefs
We aim to dissolve our fears, by understanding their causes [Epicurus]
     Full Idea: If we give a correct and complete causal account of the source of our disturbance and fears, we will dissolve them, by accounting for the phenomena to which we are constantly exposed, and which terrify other men most severely.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 82)
     A reaction: Notice 'other' men! This eudaimonist aim lies at the heart of Epicurus's physical account of the world. He was primarily interested in living better, rather than in physical science. He seeks 'tranquillity' and 'freedom from disturbance'.
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / c. Primary qualities
Atoms only have shape, weight and size, and the properties which accompany shape [Epicurus]
     Full Idea: One must believe that the atoms bring with them none of the qualities of things which appear except shape, weight, and size and the properties which necessarily accompany shape.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 54)
     A reaction: This appears to be fairly precisely a claim that atoms only have primary qualities, though that terminology only came in in the seventeenth century. I take the view to be more or less correct.
13. Knowledge Criteria / D. Scepticism / 3. Illusion Scepticism
Illusions are not false perceptions, as we accurately perceive the pattern of atoms [Epicurus, by Modrak]
     Full Idea: Epicurus says illusions are not false perceptions, because the senses accurately report the pattern of atoms; for instance, the edges are worn off the pattern produced by a square tower, so its perception as a round tower is true.
     From: report of Epicurus (Letter to Herodotus [c.293 BCE], 47-53) by Deborah K.W. Modrak - Classical theories of Mind
     A reaction: As so often, Epicurus got it right, because Democritus got it right, thus demonstrating that good philosophy must be preceded by good physics. However, good physics must be preceded and followed by good philosophy.
15. Nature of Minds / A. Nature of Mind / 2. Psuche
The soul is fine parts distributed through the body, resembling hot breath [Epicurus]
     Full Idea: The soul is a body made up of fine parts distributed throught the entire aggregate, most closely resembling breath with a certain admixture of heat, in one way resembling breath and in another resembling heat
     From: Epicurus (Letter to Herodotus [c.293 BCE], 63)
     A reaction: Remember that 'psuché' refers as much to the life within a creature as it does to the consciousness. The stoics seem to have held a similar view.
17. Mind and Body / E. Mind as Physical / 5. Causal Argument
The soul cannot be incorporeal, because then it could neither act nor be acted upon [Epicurus]
     Full Idea: Those who say that the soul is incorporeal are speaking to no point; for if it were of that character, it could neither act nor be acted upon at all.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 67)
     A reaction: This just is the causal argument, which is espoused by Papineau and other modern physicalists. Personally I am inclined to agree with Papineau, that it is so simple and conclusive that it is hardly worth discussing further. Dualism needs a miracle.
26. Natural Theory / A. Speculations on Nature / 5. Infinite in Nature
Totality has no edge; an edge implies a contrast beyond the edge, and there can't be one [Epicurus]
     Full Idea: The totality is unlimited. For what is limited has an extreme; but an extreme is seen in contrast to something else, so that since it has no extreme it has no limit.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 41)
     A reaction: I presume that the 'limit' is the edge, and the 'extreme' is what is beyond the edge. Why could not the extreme be nothingness, which then contrast dramatically with what exists?
Bodies are unlimited as well as void, since the two necessarily go together [Epicurus]
     Full Idea: The number of bodies and the magnitude of the void are unlimited. If void were unlimited, and bodies limited, bodies move in scattered fashion with no support of checking collisions; in limited void, unlimited bodies would not have a place to be in.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 42)
     A reaction: Seems good. The point is that without collisions, bodies would not stop relative to one another, and combine to form the objects we perceive. Of course if the started off (anathema!) stuck together, they may not have dispersed yet.
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / g. Atomism
There exists an infinity of each shape of atom, but the number of shapes is beyond our knowledge [Epicurus]
     Full Idea: For each type of shape there is an unlimited number of similar atoms, but with respect to the differences they are not simply unlimited but ungraspable.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 42)
     A reaction: Epicurus's view of the nature of atoms rests on his empiricism, so while he can reason from experience to how they must be, he admits (impressively) his ignorance of the full facts. He has arguments for the unlimited number.
Atoms just have shape, size and weight; colour results from their arrangement [Epicurus]
     Full Idea: There are not even any qualities in atoms, except shape and size and weight; their colour changes according to the arrangement of the atoms.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 44 schol)
     A reaction: [This is quoted by a 'scholiast' - an early writer quoting from Epicurus's '12 Basic Principles'] He appears to have got this one wrong, as it is evidently the type of atom, as well as the arrangement, which contributes to the colour.
There cannot be unlimited division, because it would reduce things to non-existence [Epicurus]
     Full Idea: One must eliminate unlimited division into smaller pieces (to avoid making everything weak and being forced in our comprehensive grasps of compound things to exhaust the things which exist by reducing them to non-existence).
     From: Epicurus (Letter to Herodotus [c.293 BCE], 56)
     A reaction: A basic argument for atoms, but it seems to rest on Zenonian paradoxes about infinite subdivision. An infinite subdivision of a unit doesn't seem to turn it into zero.
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / a. Scientific essentialism
We aim to know the natures which are observed in natural phenomena [Epicurus]
     Full Idea: Blessedness lies in knowing the natures which are observed in meteorological phenomena.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 78)
     A reaction: This pursuit of 'natures' seems to be at the heart of scientific essentialism. Epicurus demonstrates his proposal, by offering speculations about the natures of all sorts of phenomena (esp. in 'Letter to Pythocles').
27. Natural Reality / C. Space / 1. Void
The void cannot interact, but just gives the possibility of motion [Epicurus]
     Full Idea: The void can neither act nor be acted upon but merely provides the possibility of motion through itself for bodies.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 67)
     A reaction: Epicurus follows this with the anti-dualist Idea 14042, but he is at least offering the notion of something which exists without powers of causal interaction. Does space undermine the causal criterion for existence?
27. Natural Reality / C. Space / 4. Substantival Space
Space must exist, since movement is obvious, and there must be somewhere to move in [Epicurus]
     Full Idea: If there did not exist that which we call void and space and intangible nature, bodies would not have any place to be in or move through, as they obviously do move.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 40)
     A reaction: The observation that 'they obviously do move' must be aimed at followers of Parmenides. The idea of the void seems to contain a Newtonian commitment to absolute space.
27. Natural Reality / E. Cosmology / 10. Multiverse
There are endless cosmoi, some like and some unlike this one [Epicurus]
     Full Idea: There is an unlimited number of cosmoi, and some are similar to this one and some are dissimilar.
     From: Epicurus (Letter to Herodotus [c.293 BCE], 45)