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All the ideas for 'fragments/reports', 'fragments/reports' and 'The Periodic Table'

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57 ideas

2. Reason / A. Nature of Reason / 1. On Reason
Parmenides was much more cautious about accepting ideas than his predecessors [Simplicius on Parmenides]
     Full Idea: Parmenides would not agree with anything unless it seemed necessary, whereas his predecessors used to come up with unsubstantiated assertions.
     From: comment on Parmenides (fragments/reports [c.474 BCE], A28) by Simplicius - On Aristotle's 'Physics' 9.116.2-
     A reaction: from Eudemus
7. Existence / A. Nature of Existence / 3. Being / a. Nature of Being
No necessity could produce Being either later or earlier, so it must exist absolutely or not at all [Parmenides]
     Full Idea: What necessity impelled Being, if it did spring from nothing, to be produced later or earlier? Thus it must be absolutely, or not at all.
     From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1-
     A reaction: If there is a moment when Being is created, it is reasonable to ask why then, and not some other time? Obviously a conscious God can fill that gap,but that only defers the problem.
Being is not divisible, since it is all alike [Parmenides]
     Full Idea: Being is not divisible, since it is all alike.
     From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1-
     A reaction: A baffling proposal when it appears to be extremely diverse. A microscope would have forced him to rethink somewhat.
Being must be eternal and uncreated, and hence it is timeless [Parmenides]
     Full Idea: Being has no coming-to-be and no destruction, for it is whole of limb, without motion, and without end. And it never was, nor will be, because it is now, a whole all together, one, continuous; for what creation of it will you look for?
     From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1-
     A reaction: That being is eternal is a reasonable speculation, since its creation seems inconceivable. But why think it is without motion, when we see motion everywhere? That was Aristotle's reaction, too.
7. Existence / A. Nature of Existence / 3. Being / d. Non-being
The realm of necessary non-existence cannot be explored, because it is unknowable [Parmenides]
     Full Idea: The other way of enquiry, that IT IS NOT, and IT is bound NOT TO BE, cannot be explored, for you could neither recognise nor express that which IS NOT.
     From: Parmenides (fragments/reports [c.474 BCE], B02), quoted by Simplicius - On Aristotle's 'Physics' 9.116.28-
     A reaction: There is not much to say about that which is not, but quite a lot, I would have thought, about what is 'bound not to be'. What prevents it from being?
There is no such thing as nothing [Parmenides]
     Full Idea: There is no such thing as nothing.
     From: Parmenides (fragments/reports [c.474 BCE], B06), quoted by Simplicius - On Aristotle's 'Physics' 9.86.27-
     A reaction: See Meinong on this. It is not an empty concept, because things can be predicated of nothing, such as weighing less than an apple. CF. the role of zero in arithmetic.
7. Existence / A. Nature of Existence / 3. Being / f. Primary being
Parmenides at least saw Being as the same as Nous, and separate from the sensed realm [Parmenides, by Plotinus]
     Full Idea: Parmenides made some approach to the doctrine of Plato in identifying Being with Intellectual-Principle [Nous] while separating Real Being from the realm of sense.
     From: report of Parmenides (fragments/reports [c.474 BCE]) by Plotinus - The Enneads 5.1.08
     A reaction: The point is that for Parmenides the One is the essence of Being, but for platonists there is something prior to and higher than Being. For Plato it is the Good; for Plotinus it is a revised (non-Being) concept of the One.
7. Existence / B. Change in Existence / 1. Nature of Change
All our concepts of change and permanence are just names, not the truth [Parmenides]
     Full Idea: All things that mortals have established, believing in their truth, are just a name: Becoming and Perishing, Being and Not-Being, and change of position, and alteration of bright colour.
     From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1-
     A reaction: He has to say this, once he has decided that Being is homogeneous eternal unity, but if normal human beliefs are just names, presumably that applies to his views too. Is 'Being' just a name?
9. Objects / E. Objects over Time / 1. Objects over Time
Something must be unchanging to make recognition and knowledge possible [Aristotle on Parmenides]
     Full Idea: Parmenides and Melissus were the first to appreciate that there must be unchanging entities, if recognition and knowledge are to exist.
     From: comment on Parmenides (fragments/reports [c.474 BCE], A25) by Aristotle - On the Heavens 298b14
10. Modality / A. Necessity / 5. Metaphysical Necessity
The first way of enquiry involves necessary existence [Parmenides]
     Full Idea: The first way of enquiry is the one that IT IS, and it is not possible for IT NOT TO BE, which is the way of credibility, for it follows truth.
     From: Parmenides (fragments/reports [c.474 BCE], B02), quoted by Simplicius - On Aristotle's 'Physics' 9.116.28-
     A reaction: also Proclus 'Timeus'
10. Modality / A. Necessity / 8. Transcendental Necessity
Necessity sets limits on being, in order to give it identity [Parmenides]
     Full Idea: Powerful necessity holds Being in the bonds of a limit, which constrains it round about, because divine law decrees that Being shall not be without boundary. For it is not lacking, but if it were spatially infinite, it would lack everything.
     From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1-
11. Knowledge Aims / B. Certain Knowledge / 4. The Cogito
Thinking implies existence, because thinking depends on it [Parmenides]
     Full Idea: To think is the same as the thought that IT IS, for you will not find thinking without Being, on which it depends for its expression.
     From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1-
12. Knowledge Sources / B. Perception / 1. Perception
Parmenides treats perception and intellectual activity as the same [Theophrastus on Parmenides]
     Full Idea: Parmenides treats perception and intellectual activity as the same.
     From: comment on Parmenides (fragments/reports [c.474 BCE], A46) by Theophrastus - On the Senses 3.1
     A reaction: cf Theaetetus pt 1
12. Knowledge Sources / C. Rationalism / 1. Rationalism
Only reason can prove the truth of facts [Parmenides]
     Full Idea: Reason alone will prove the truth of facts.
     From: Parmenides (fragments/reports [c.474 BCE]), quoted by Diogenes Laertius - Lives of Eminent Philosophers 09.3.3
14. Science / A. Basis of Science / 4. Prediction
If a theory can be fudged, so can observations [Scerri]
     Full Idea: A theorist may have designed his theory to fit the facts, but is it not equally possible for observers to be influenced by a theory in their report of experimental facts?
     From: Eric R. Scerri (The Periodic Table [2007], 05 'Power')
     A reaction: This is in reply to Lipton's claim that prediction is better than accommodation because of the 'fudging' problem. The reply is that you might fudge to achieve a prediction. If it was correct, that wouldn't avoid the charge of fudging.
14. Science / B. Scientific Theories / 4. Paradigm
The periodic system is the big counterexample to Kuhn's theory of revolutionary science [Scerri]
     Full Idea: The history of the periodic system appears to be the supreme counterexample to Kuhn's thesis, whereby scientific developments proceed in a sudden, revolutionary fashion.
     From: Eric R. Scerri (The Periodic Table [2007], 03 'Rapid')
     A reaction: What is lovely about the periodic table is that it seems so wonderfully right, and hence no revolution has ever been needed. The big theories of physics and cosmology are much more precarious.
14. Science / D. Explanation / 1. Explanation / b. Aims of explanation
Scientists eventually seek underlying explanations for every pattern [Scerri]
     Full Idea: Whenever scientists are presented with a useful pattern or system of classification, it is only a matter of time before the begin to ask whether there may be some underlying explanation for the pattern.
     From: Eric R. Scerri (The Periodic Table [2007], Intro 'Evol')
     A reaction: Music to my ears, against the idea that the sole aim of science is accurately describe the patterns.
14. Science / D. Explanation / 3. Best Explanation / a. Best explanation
The periodic table suggests accommodation to facts rates above prediction [Scerri]
     Full Idea: Rather than proving the value of prediction, the development and acceptance of the periodic table may give us a powerful illustration of the importance of accommodation, that is, the ability of a new scientific theory to explain already known facts.
     From: Eric R. Scerri (The Periodic Table [2007], 05 'Intro')
     A reaction: The original table made famous predictions, but also just as many wrong ones (Scerri:143), and Scerri thinks this aspect has been overrated.
19. Language / B. Reference / 1. Reference theories
The Electra: she knows this man, but not that he is her brother [Eucleides, by Diog. Laertius]
     Full Idea: The 'Electra': Electra knows that Orestes is her brother, but not that this man is Orestes, so she knows and does not know her brother simultaneously.
     From: report of Eucleides (fragments/reports [c.410 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 02.Eu.4
     A reaction: Hence we distinguish 'know of', 'know that' and 'know how'. Hence Russell makes 'knowledge by acquaintance' fundamental, and descriptions come later.
22. Metaethics / C. The Good / 1. Goodness / b. Types of good
The chief good is unity, sometimes seen as prudence, or God, or intellect [Eucleides]
     Full Idea: The chief good is unity, which is known by several names, for at one time people call it prudence, at another time God, at another intellect, and so on.
     From: Eucleides (fragments/reports [c.410 BCE]), quoted by Diogenes Laertius - Lives of Eminent Philosophers 02.9.2
     A reaction: So the chief good is what unites and focuses our moral actions. Kant calls that 'the will'.
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / e. The One
The one is without any kind of motion [Parmenides]
     Full Idea: The one is without any kind of motion.
     From: Parmenides (fragments/reports [c.474 BCE]), quoted by Plato - Parmenides 139a
There could be movement within one thing, as there is within water [Aristotle on Parmenides]
     Full Idea: Why does it follow from there being only one thing that it is unmoving, since, for example, water moves internally while remaining one?
     From: comment on Parmenides (fragments/reports [c.474 BCE]) by Aristotle - Physics 186a16
     A reaction: One suspects that Parmenides wasn't used to critical questions like this, and would have sharpened up his theory if it had been subjected to criticism. How big was the One? Maybe Aristotle is the real father of philosophy.
The one can't be divisible, because if it was it could be infinitely divided down to nothing [Parmenides, by Simplicius]
     Full Idea: Since the one is everywhere alike, then if it is divisible, it will be equally divisible everywhere….so let it be divided everywhere. It is obvious that nothing will remain and the whole will vanish, and so (if it is compound) it is composed of nothing.
     From: report of Parmenides (fragments/reports [c.474 BCE]) by Simplicius - On Aristotle's 'Physics' 9.139.5-
     A reaction: he is quoting Porphyry
Defenders of the One say motion needs the void - but that is not part of Being [Parmenides, by Aristotle]
     Full Idea: Defenders of the One say that there could not be motion without a void, and that void is what does not exist, and that nothing that is not belongs to being.
     From: report of Parmenides (fragments/reports [c.474 BCE]) by Aristotle - Coming-to-be and Passing-away (Gen/Corr) 325a26
     A reaction: This is why motion is an illusion, a view also supported by the paradoxes of Zeno of Elea. Aristotle goes on to give Democritus's response to this idea. Parmenides was contemplating 'void', before Democritus got to it.
Reason sees reality as one, the senses see it as many [Aristotle on Parmenides]
     Full Idea: Since he is forced to be guided by appearances, he assumes that the one exists from the viewpoint of reason, but that a plurality exists from the viewpoint of the sense, and so he posits two principles and causes - hot and cold.
     From: comment on Parmenides (fragments/reports [c.474 BCE], A24) by Aristotle - Metaphysics 986b27-
     A reaction: A profound thought. Empiricists emphasies experience, and end up with fragmented reality. Reason explains experience, and in the process sees the world as unities (like objects), though a single unity is going too far.
Reality is symmetrical and balanced, like a sphere, with no reason to be greater one way rather than another [Parmenides]
     Full Idea: Since there is a spatial limit, it is complete on every side, like the mass of a well-rounded sphere, equally balanced from its centre in every direction; for it is not bound to be at all either greater or less in this direction or that.
     From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1-
People who say that the cosmos is one forget that they must explain movement [Aristotle on Parmenides]
     Full Idea: Those who assert that the universe is one and a single nature, when they try to give the causes of generation and destruction, miss out the cause of movement.
     From: comment on Parmenides (fragments/reports [c.474 BCE]) by Aristotle - Metaphysics 988b
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / f. Ancient elements
He taught that there are two elements, fire the maker, and earth the matter [Parmenides, by Diog. Laertius]
     Full Idea: He taught that there were two elements, fire and earth; and that one of them occupies the place of the maker, the other that of the matter.
     From: report of Parmenides (fragments/reports [c.474 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 09.Pa.2
26. Natural Theory / B. Natural Kinds / 1. Natural Kinds
Natural kinds are what are differentiated by nature, and not just by us [Scerri]
     Full Idea: Natural kinds are realistic scientific entities that are differentiated by nature itself rather than by our human attempts at classification.
     From: Eric R. Scerri (The Periodic Table [2007], Intro 'Evol')
If elements are natural kinds, might the groups of the periodic table also be natural kinds? [Scerri]
     Full Idea: Elements defined by their atomic numbers are frequently assumed to represent 'natural kinds' in chemistry. ...The question arises as to whether groups of elements appearing in the periodic table might also represent natural kinds.
     From: Eric R. Scerri (The Periodic Table [2007], 10 'Elements')
     A reaction: Scerri says the distinction is not as sharp as that between the elements. As a realist, he believes there is 'one ideal periodic classification', which would then make the periods into kinds.
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / a. Scientific essentialism
The colour of gold is best explained by relativistic effects due to fast-moving inner-shell electrons [Scerri]
     Full Idea: Many seemingly mundane properties of elements such as the characteristic color of gold ....can best be explained by relativistic effects due to fast-moving inner-shell electrons.
     From: Eric R. Scerri (The Periodic Table [2007], 01 'Under')
     A reaction: John Locke - I wish you were reading this! That we could work out the hidden facts of gold, and thereby explain and predict the surface properties we experience, is exactly what Locke thought to be forever impossible.
27. Natural Reality / A. Classical Physics / 1. Mechanics / a. Explaining movement
It is feeble-minded to look for explanations of everything being at rest [Aristotle on Parmenides]
     Full Idea: For people to ignore the evidence of their senses and look for an explanation for everything being at rest is feeble-minded.
     From: comment on Parmenides (fragments/reports [c.474 BCE]) by Aristotle - Physics 253a32
     A reaction: Not exactly an argument, but an interestingly robust assertion of commonsense against dodgy arguments. Aristotle is not exactly an empiricist, but he is on that side of the fence.
27. Natural Reality / B. Modern Physics / 4. Standard Model / a. Concept of matter
If all elements are multiples of one (of hydrogen), that suggests once again that matter is unified [Scerri]
     Full Idea: The work of Moseley and others rehabilitated Prout's hypothesis that all elements were composites of hydrogen, being exact multiples of 1. ..This revitalized some philososophical notions of the unity of all matter, criticised by Mendeleev and others.
     From: Eric R. Scerri (The Periodic Table [2007], 06 'Philos')
The stability of nuclei can be estimated through their binding energy [Scerri]
     Full Idea: The stability of nuclei can be estimated through their binding energy, a quantity given by the difference between their masses and the masses of their constituent particles.
     From: Eric R. Scerri (The Periodic Table [2007], 10 'Stabil')
27. Natural Reality / C. Space / 1. Void
The void can't exist, and without the void there can't be movement or separation [Parmenides, by Aristotle]
     Full Idea: Some philosophers thought what is must be one and immovable. The void, they say, is not: but unless there is a void what is cannot be moved, nor can it be many, since there is nothing to keep things apart.
     From: report of Parmenides (fragments/reports [c.474 BCE]) by Aristotle - Coming-to-be and Passing-away (Gen/Corr) 325a06
     A reaction: Somehow this doesn't seem very persuasive any more! I suppose we would distinguish various degrees of void, and assert the existence of sufficient void to allow movement and separation. We must surely agree that total nothingness doesn't exist.
27. Natural Reality / D. Time / 3. Parts of Time / a. Beginning of time
What could have triggered the beginning [of time and being]? [Parmenides]
     Full Idea: What need would have aroused it later or sooner, starting from nothing to come into being?
     From: Parmenides (fragments/reports [c.474 BCE]), quoted by Robin Le Poidevin - Travels in Four Dimensions 02 'Everything'
     A reaction: [Barnes 1982:178] This remains an excellent question. The last I heard was a 'quantum fluctuation', but that seems to be an event, which therefore needs time.
27. Natural Reality / E. Cosmology / 1. Cosmology
He was the first to discover the identity of the Morning and Evening Stars [Parmenides, by Diog. Laertius]
     Full Idea: He appears to have been the first to discover that Hesperus and Lucifer were the same star.
     From: report of Parmenides (fragments/reports [c.474 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 09.Pa.3
     A reaction: This is the famous example used by Frege to discuss reference and meaning.
He was the first person to say the earth is spherical [Parmenides, by Diog. Laertius]
     Full Idea: He was the first person who asserted that the earth was of a spherical form.
     From: report of Parmenides (fragments/reports [c.474 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 09.Pa.2
27. Natural Reality / F. Chemistry / 1. Chemistry
The electron is the main source of chemical properties [Scerri]
     Full Idea: It is the electron that is mainly responsible for the chemical properties of the elements.
     From: Eric R. Scerri (The Periodic Table [2007], 06 'Intro')
Does radioactivity show that only physics can explain chemistry? [Scerri]
     Full Idea: Some authors believe that the interpretation of the properties of the elements passed from chemistry to physics as a result of the discovery of radioactivity. ...I believe this view to be overly reductionist.
     From: Eric R. Scerri (The Periodic Table [2007], 06 'Radio')
     A reaction: It is all a matter of the explanations, and how far down they have to go. If most non-radiocative chemistry doesn't need to mention the physics, then chemistry is largely autonomous.
A big chemistry idea is that covalent bonds are shared electrons, not transfer of electrons [Scerri]
     Full Idea: One of the most influential ideas in modern chemistry is of a covalent bond as a shared pair of electrons (not as transfer of electrons and the formation of ionic bonds).
     From: Eric R. Scerri (The Periodic Table [2007], 08 'Intro')
     A reaction: Gilbert Newton Lewis was responsible for this.
How can poisonous elements survive in the nutritious compound they compose? [Scerri]
     Full Idea: A central mystery of chemistry is how the elements survive in the compounds they form. For example, how can poisonous grey metal sodium combine with green poisonous gas chlorine, to make salt, which is non-poisonous and essential for life?
     From: Eric R. Scerri (The Periodic Table [2007], Intro 'Elem')
     A reaction: A very nice question which had never occurred to me. If our digestive system pulled the sodium apart from the chlorine, we would die.
Periodicity and bonding are the two big ideas in chemistry [Scerri]
     Full Idea: The two big ideas in chemistry are chemical periodicity and chemical bonding, and they are deeply interconnected.
     From: Eric R. Scerri (The Periodic Table [2007], Intro 'Per')
Chemistry does not work from general principles, but by careful induction from large amounts of data [Scerri]
     Full Idea: Unlike in physics, chemical reasoning does not generally proceed unambiguously from general principles. It is a more inductive science in which large amounts of observational data must be carefully weighed.
     From: Eric R. Scerri (The Periodic Table [2007], 05 'Mendel')
     A reaction: This is why essentialist thinking was important for Mendeleev, because it kept his focus on the core facts beneath the messy and incomplete data.
27. Natural Reality / F. Chemistry / 2. Modern Elements
19th C views said elements survived abstractly in compounds, but also as 'material ingredients' [Scerri]
     Full Idea: In the 19th century abstract elements were believed to be permanent and responsible for observed properties in compounds, but (departing from Aristotle) they were also 'material ingredients', thus linking the metaphysical and material realm.
     From: Eric R. Scerri (The Periodic Table [2007], 04 'Nature')
     A reaction: I'm not sure I can make sense of this gulf between the metaphysical and the material realm, so this was an account heading for disaster.
It is now thought that all the elements have literally evolved from hydrogen [Scerri]
     Full Idea: The elements are now believed to have literally evolved from hydrogen by various mechanisms.
     From: Eric R. Scerri (The Periodic Table [2007], 10 'Evol)
27. Natural Reality / F. Chemistry / 3. Periodic Table
To explain the table, quantum mechanics still needs to explain order of shell filling [Scerri]
     Full Idea: The order of shell filling has not yet been deduced from first principles, and this issue cannot be avoided if one is to really ask whether quantum mechanics explains the periodic system in a fundamental manner.
     From: Eric R. Scerri (The Periodic Table [2007], 09 'From')
Elements were ordered by equivalent weight; later by atomic weight; finally by atomic number [Scerri]
     Full Idea: Historically, the ordering of elements across periods was determined by equivalent weight, then later by atomic weight, and eventually by atomic number.
     From: Eric R. Scerri (The Periodic Table [2007], 01 'React')
     A reaction: So they used to be ordered by quantities (measured by real numbers), but eventually were ordered by unit items (counted by natural numbers). There need to be distinct protons (unified) to be counted.
Moseley showed the elements progress in units, and thereby clearly identified the gaps [Scerri]
     Full Idea: Moseley's work showed that the successive elements in the periodic table have an atomic number greater by one unit. The gaps could then be identified definitively, as 43, 61, 72, 75, 85, 87, and 91.
     From: Eric R. Scerri (The Periodic Table [2007], 06 'Henry')
     A reaction: [compressed]
Elements are placed in the table by the number of positive charges - the atomic number [Scerri]
     Full Idea: The serial number of an element in the periodic table, its atomic number, corresponds to the number of positive charges in the atom.
     From: Eric R. Scerri (The Periodic Table [2007], 07 'Models')
     A reaction: Note that this is a feature of the nucleus, despite that fact that the electrons decide the chemical properties. A nice model for Locke's views on essentialism.
Moseley, using X-rays, showed that atomic number ordered better than atomic weight [Scerri]
     Full Idea: By using X-rays, Henry Moseley later discovered that a better ordering principle for the periodic system is atomic numbers rather than atomic weight, by subjecting many different elements to bombardment.
     From: Eric R. Scerri (The Periodic Table [2007], 06 'Intro')
     A reaction: Moseley was killed in the First World War at the age of 26. It is interesting that they more or less worked out the whole table, before they discovered the best principle on which to found it.
Some suggested basing the new periodic table on isotopes, not elements [Scerri]
     Full Idea: Some chemists even suggested that the periodic table would have to be abandoned in favor of a classification system that included a separate place for every single isotope.
     From: Eric R. Scerri (The Periodic Table [2007], 06 'Intro')
     A reaction: The extreme case is tin, which has 21 isotopes, so is tin a fundamental, or is each of the isotopes a fundamental? Does there have to be a right answer to that? All tin isotopes basically react in the same way, so we stick with the elements table.
Pauli explained the electron shells, but not the lengths of the periods in the table [Scerri]
     Full Idea: Pauli explained the maximum number of electrons successive shells can accommodate, ...but it does not explain the lengths of the periods, which is the really crucial property of the periodic table.
     From: Eric R. Scerri (The Periodic Table [2007], 07 'Pauli')
     A reaction: Paulis' Exclusion Principle says no two electrons in an atom can have the same set of four quantum numbers. He added 'spin' as a fourth number. It means 'electrons cannot be distinguished' (243). Scerri says the big problem is still not fully explained.
Orthodoxy says the periodic table is explained by quantum mechanics [Scerri]
     Full Idea: The prevailing reductionist climate implies that quantum mechanics inevitably provides a more fundamental explanation for the periodic system.
     From: Eric R. Scerri (The Periodic Table [2007], 08 'Concl')
     A reaction: Scerri has argued that chemists did much better than physicists in working out how the outer electron shells of atoms worked, by induction from data, rather than inference from basic principles.
The best classification needs the deepest and most general principles of the atoms [Scerri]
     Full Idea: An optimal classification can be obtained by identifying the deepest and most general principles that govern the atoms of the elements.
     From: Eric R. Scerri (The Periodic Table [2007], 10 'Continuum')
     A reaction: He adds (p.286) that the best system will add the 'greatest degree of regularity' to these best principles.
Elements in the table are grouped by having the same number of outer-shell electrons [Scerri]
     Full Idea: The modern notion is that atoms fall into the same group of the periodic table if they possess the same numbers of outer-shell electrons.
     From: Eric R. Scerri (The Periodic Table [2007], 07 'Quantum')
     A reaction: Scerri goes on to raise questions about this, on p.242. By this principle helium should be an alkaline earth element, but it isn't.
Since 99.96% of the universe is hydrogen and helium, the periodic table hardly matters [Scerri]
     Full Idea: All the elements other than hydrogen and helium make up just 0.04% of the universe. Seen from this perspective, the periodic table appears to rather insignificant.
     From: Eric R. Scerri (The Periodic Table [2007], 10 'Astro')