The problem with reductionism

If one wants to go down the rabbit hole of what constitutes emergent behavior ... all things in nature are emergent from the consituent components of gluons and the four fundamental forces.
 
Sabine in her typically clear-cut manner offers some fascinating insights into the science of emergence and complexity...

 
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Magical Realist said:
You seem to be saying that an emergent property can be traced to the combined behavior/properties of its subunits. I'm saying it is more than that, at least in the case of strong emergence. It is more than the mere sum of the parts. My favorite example is salt. The two atomic elements of chlorine and sodium, which in themselves are highly reactive and dangerous, combine to create common table salt. The properties of salt, its distinctive taste, solubility in water, ability to conduct electricity when in solution, and crystal structure, are not present in its two elements either discretely nor in summation. They are entirely new and surprising properties. Do we really understand how this happens? No.. We may certainly say that they are caused by the combination of chlorine and sodium. But we do not understand how salt's emergent properties rationally or necessarily follow, in a lawlike fashion, from this reaction,. That's why I said in the op that this becomes a matter of how we ultimately define understanding something. Is it enough to say they are just the magical combination of their components, without knowing HOW that combination results in the given properties? Or is there more to be discovered?
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We do understand salt, it is what the electrons are doing. The universe wants to be neutral.
Electron "shells" want to be stable.
That is all chemistry is, electrons forming and breaking bonds.
If it is a very strong bond then they will sit there until a lot of energy comes along.
If exchemist only had 22 words to summarise Chemistry I would like to see his expert view
 
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Magical Realist said:
You seem to be saying that an emergent property can be traced to the combined behavior/properties of its subunits. I'm saying it is more than that, at least in the case of strong emergence. It is more than the mere sum of the parts. My favorite example is salt. The two atomic elements of chlorine and sodium, which in themselves are highly reactive and dangerous, combine to create common table salt. The properties of salt, its distinctive taste, solubility in water, ability to conduct electricity when in solution, and crystal structure, are not present in its two elements either discretely nor in summation. They are entirely new and surprising properties. Do we really understand how this happens? No.. We may certainly say that they are caused by the combination of chlorine and sodium. But we do not understand how salt's emergent properties rationally or necessarily follow, in a lawlike fashion, from this reaction,. That's why I said in the op that this becomes a matter of how we ultimately define understanding something. Is it enough to say they are just the magical combination of their components, without knowing HOW that combination results in the given properties? Or is there more to be discovered?
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You seem determined to stick to a wrong idea about what emergent properties are. I've already explained what emergent means twice now. Looks as if I need to do it a 3rd time.

No the properties of salt are not surprising to anyone who understands chemistry. The purpose of chemistry is to be able to account for such things and thereby predict behaviour of substances. What you assert here is utterly false.

Sodium (Na) is in the Alkali Metals column of the Periodic Table. That means its atoms have a single, weakly bound electron in the outer (valence) shell. That means Na readily loses one electron to become an ion, Na⁺. Chlorine (Cl) atoms by contrast are one electron short of a full valence shell. Because nuclear charge goes up across a period, the valence shell is progressvely pulled in by stronger attraction, so by the time we get to Cl its electrons are much more strongly bound than for Na. As a result, Cl readily accepts one extra electron into the gap in its shell to form an ion, Cl⁻. When you put Na metal and Cl gas together you get an explosive reaction, releasing a lot of heat, because the product, NaCl is in a much lower energy state than the reactants, due to the transfer of a weakly bound electron to an atom that binds it much more strongly.

The crystal structure of NaCl is a face-centred cubic (fcc) structure. The positive ions are attracted to the negative ones, so the closer they can get the lower the energy will be. The smaller Na⁺ ions fit neatly between the larger Cl⁻ ions, allowing them to approach one another closely and minimise the energy of the system. This accounts for the high melting point of salt - an emergent property, because the melting point of a single molecule or ion is a meaningless notion.

The high solubility is more complex to explain. Firstly there is competition between the electrostatic attraction within the crystal and the electrostatic attraction of the polar water molecules that surround a dissolved ion: in other words between the bonding in the crystal vs. the bonding in the solvated state. But entropy also plays quite a role. The dissolved ions move around randomly and have higher entropy than the orderly crystal strucuture. But the formation of a solvation shell of water molecules around each ion involves them lining up with their +ve or -ve ends towards the ion as appropriate. That aligning process involves a reduction in entropy. So there's a trade-off in entropy. The solubility of a given salt is determined by the net outcome of all of this, according to the formula ΔG = ΔH -TΔS, in which ΔG is the change in Gibbs free energy. The more -ve this is, the further the reaction will go, i.e.the higher the solubility. ΔH is the enthalpy change, more or less indicating the net change in strength of the chemical bonds broken and formed in the reaction and ΔS is te entropy change. T is the absolute temperature. (If the entropy of the dissolved state is higher than the undissolved state, the TΔS term will make ΔG more -ve as the temperature goes up. This is why the solubility of salt is higher in warm water and so a warm saturated solution will precipitate crystals as it cools.)

The electrical conductivity in solution is obviously explained by the fact that NaCl is an ionic compound, so a solution contains +ve and -ve ions that move towards electrodes and get discharged there, enabling electric current to flow. If instead you dissolve, say, sugar in water, no ions are produced so no significant change in conductivity takes place. Electrical conductivity is again an emergent property. It is meaningless to speak of the conductivity of a single molecule or ion.

So none of the above seems to me to involve an element of mystery that can't be explained in terms of the behaviour of the constituent parts. It's just chemistry.

The taste of salt is different from all of the above though. It requires a lot of subtle biochemistry to explain how the receptors on the tongue work. But even then, "taste" is a subjective sensation, like colour. It's a quale (plural qualia), so not amenable to direct scientific investigation. Science can account for why animals such as ourselves get a sensation when salt is present, but not what it is "like".
 
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Pinball1970 said:
We do understand salt, it is what the electrons are doing. The universe wants to be neutral.
Electron "shells" want to be stable.
That is all chemistry is, electrons forming and breaking bonds.
If it is a very strong bond then they will sit there until a lot of energy comes along.
If exchemist only had 22 words to summarise Chemistry I would like to see his expert view
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Gosh it's hard to put into 22 words. I suppose I would say something like: study of the behaviour and properties of substances and the reactions between them. But of course you will object I've offloaded a lot onto the term "substances". :)
 
exchemist said:
Gosh it's hard to put into 22 words. I suppose I would say something like: study of the behaviour and properties of substances and the reactions between them. But of course you will object I've offloaded a lot onto the term "substances". :)
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Even more concise than mine! I have a good one for Physics, fields and their associated particles and forces.
 
Magical Realist said:
Science takes everything apart and reduces it down to its most basic components in order to understand it better. Which is essentially like extracting all the ingredients from a delicious homemade stew in order to understand it better. There is a distinctive character and "whatness" in the whole that is missed out on in the reductive analyses of its discrete parts.
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Not quite fair account of all science, given there are fields like ecology or atmospheric science which often use a holistic approach to understand complex systems. This is also true of behavioral sciences.
 
Pinball1970 said:
Even more concise than mine! I have a good one for Physics, fields and their associated particles and forces.
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Yes, that’s even worse than mine! :biggrin:. I get the term “substances” to do a lot of heavy lifting, without defining it, but you go one better and use no fewer than three concepts that need a pre-existing understanding of physics to mean anything!

So I really ought to define what I mean by a substance, but you need to define a force, a particle (that most artificial and dodgy of idealised concepts) and most of all, a field.

Coming up with a definition that is not self-referential is quite tricky, especially for physics. I look forward to your definition of a field, especially!:p
 
exchemist said:
Yes, that’s even worse than mine! :biggrin:. I get the term “substances” to do a lot of heavy lifting, without defining it, but you go one better and use no fewer than three concepts that need a pre-existing understanding of physics to mean anything!

So I really ought to define what I mean by a substance, but you need to define a force, a particle (that most artificial and dodgy of idealised concepts) and most of all, a field.

Coming up with a definition that is not self-referential is quite tricky, especially for physics. I look forward to your definition of a field, especially!:p
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That's not cricket!

If I use "field" to a photographer, a farmer, a physicist and a mathematician i will get different answers.

Context is everything.

Deep purple were a "force" of nature!
 
Pinball1970 said:
Dave if you push me down this road trust me, I will come to Toronto and start a MAJOR leaflet campaign.
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Perhaps do a few open mike sessions with my acoustic. Is that what you want? Is it?

Besides that fella hope you and the family are ok. Love to all.
 
Pinball1970 said:
Not all fields are equal, some fall off with the reciprocal of the distance squared.The Higgs field is different and others, what about the DM Field?
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But seriously how do you define what a field is in physics? It takes a least a paragraph, doesn't it?

It's some kind of latent property, spread out in space, with different values at each point. The property is latent as it is only actualised when some entity is placed in the field, which is subject to its influence. Or something. Er......
 
exchemist said:
But seriously how do you define what a field is in physics? It takes a least a paragraph, doesn't it?

It's some kind of latent property, spread out in space, with different values at each point. The property is latent as it is only actualised when some entity is placed in the field, which is subject to its influence. Or something. Er......
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Each point in space has a value (W4U don't you dare) with respect to that particular field at that time.
 
exchemist said:
Gosh it's hard to put into 22 words. I suppose I would say something like: study of the behaviour and properties of substances and the reactions between them. But of course you will object I've offloaded a lot onto the term "substances". :)
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I took a basic physics class in college. On the first day my teacher defined mass as "stuff".
 
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