Antiatomism

[Resha Caner]

Is anyone familiar with Pierre Duhem's resistance to the atomic model? He is often quoted amongst philosophers of science, and I understand most of his argument, except the one against the atomic model.

 

Be gentle with me. I've never been good with chemistry, and that may be why I'm struggling.

 

Here is his quote about the "law of multiple proportions":

 

"The masses of bodies A, B, and C combining to form the compound M are to one another as the three numbers a, b, and c. Then the masses of the elements A, B, and C combining to form the compound M' will be to one another as the numbers xa, yb, and zc (x, y, and z being three whole numbers). ... Now, in whatever relations the elements A, B, and C are combined within the compound M', we can always represent these relations with as close an approximation as you please, by the mutual relations of three products xa, yb, and zc ... in other words, whatever the results given by the chemical analysis of the compound M', we are always sure to find three integers x, y, and z."

[Sayonara]

It seems like he is saying, in a VERY roundabout and complicated way, that a compound made up of the elements A, B, and C will always yield those elements in the same proportion.

 

For example, 1 molecule of triose will always break down to 3 carbon, 3 oxygen, and 2 hydrogen. Increase the number of molecules of triose, and you increase the number of atoms of the elements that make up those molecules accordingly, but they remain in the same proportion.

[insane_alien]

i'm not sure how that it is supposed to refute the atomic model.

 

i though the last of those went away when we actually took a picture of individual atoms.

 

then again i would have thought flat earthers would have disappeared when we measured the diameter of the earth over 2000 years ago.

[Dak]

"The masses of bodies A, B, and C combining to form the compound M are to one another as the three numbers a, b, and c. Then the masses of the elements A, B, and C combining to form the compound M' will be to one another as the numbers xa, yb, and zc (x, y, and z being three whole numbers). ... Now, in whatever relations the elements A, B, and C are combined within the compound M', we can always represent these relations with as close an approximation as you please, by the mutual relations of three products xa, yb, and zc ... in other words, whatever the results given by the chemical analysis of the compound M', we are always sure to find three integers x, y, and z."

 

umm...

 

A,B,C = elements

a,b,c = mass of said elements

x,y,z = number of atoms

M = mass of molecule

 

so, a molecule consisting of elements A and B will have a mass of xa + yb.

 

H2O weighs 2 * mass of H + 1 * mass of O

 

i think is what he's saying...

[Resha Caner]

OK, I guess no one is familiar with the argument. You seem just as confused as I am.

 

Let me give some historical context. First of all, Duhem died in 1916, only 3 years after Bohr introduced his model. So, his opposition to the atomic model is not as "flat earth" as it may seem. The atomic idea was not at all obvious when it recurred (and it was a recurrence - what some viewed as a resurrection of ancient Greek mysticism). Duhem was active in opposing the atomic model and the onset of quantum physics.

 

Of course he "lost" the battle, so it appears he has been largely forgotten in science textbooks. But, he has not been forgotten on the philosophical side of science. The "Duhem-Quine Thesis" is a big deal.

 

His antiatomism is only an example of the thesis, not the thesis itself, which has significant weight to it.

 

Another example involves gravity, and that one I get. Gravitation says that a body accelerates toward the earth at a constant rate. Duhem asks what it would take to refute such a law (that's easy for us to imagine post-Einstein, but it was a revolutionary question for Duhem's day). He claims that if someone found a body was not accelerating at a constant rate, they wouldn't assume the law was wrong, but that some other force acted on the body. Therefore, the law never gets challenged.

 

He is trying to pose a similar argument for the law of multiple proportions. He's saying that since we assume it to be correct, we explain away the deviations, thereby reinforcing the law rather than refuting it.

 

But his argument confuses me, and I don't see how his example demonstrates that an alternative explanation exists. I wonder if I'm locked into a paradigm and that's why I can't see what he's saying, or if he's just spouting nonsense.

 

It seems no one has heard of him before. Maybe posting more of the essay from the book I'm reading would help, but that seems a copyright infringement. I've been hunting to see if it's available online somewhere.

[DJBruce]

I am some what confused. I do not see how his argument disproves anything.

 

Also the Atomic Model is very very old. It original proposed (very basically) by Democritus in 450 BC. The modern version was came into being in the early 1800's (Dalton's Model). And was proven by Einstein in 1905 in his Annus Mirabilis Papers. So I do not see how Duhem would not be aware of the atomic model.

 

Also Bohr did not do any work on the Law of Multiple Proportions. Most of his work was on the model of the hydrogen atom and working out the basics of Quantum Mechanics.

[insane_alien]

rutherfords experiments on the structure of atoms was also before then. and his discoveries are reasonably close to modern day theories (small positively charged nucleus, cloud of negative charge in a cloud around it).

 

there are older models that are less accurate as well.

[John Cuthber]

I think (though I'm not sure) that he is trying to refute the idea that the law of multiple proportions is stronge evidence for atoms.

 

Hydrogen forms 2 oxides- H2O and H2O2

For a given mass of hydrogen the mass of oxygen combined with it in these 2 compounds is in a simple proportion. 1 to 2.

 

Similarly for iron there are 2 chlorides, for the same mass of iron you can get two different chlorides, one with 2/3 times as much chlorine as the other. Again, it's a simple proportion.

 

These simple ratios make sense for compounds made from atoms, but if there were no atoms to do the "counting" how would the numbers "know" how to come out as simple ratios?

To me that seems like strong evidence that there are atoms, and it's among the first "scientific" evidence of atoms that was available.

 

Now what this guy is saying is that if you have 2 compounds of some sort and you measure the proprtion of, for example chlorine, and they come out as 123456789 to 234567891 then you can still say that's a "simple" pair of numbers- in fact, for any ratio, there will be a pair of numbers that give "close enough" to the right ratio so you could claim that the compound is made from 123465789 chlorines in one case and 234567891 chlorines in the other.

 

Of course some of us might say that 2:3 and 1:2 are a lot more sensible.

 

However he has got something of a point because there are non stoiciometric compounds where the ratios are not exact numbers, for example FeO practically never has exactly the same number of oxygens as iron atoms.

[Resha Caner]

... in fact, for any ratio, there will be a pair of numbers that give "close enough" to the right ratio ...

 

Excellent. Thanks, John. It finally clicked for me, and I get what he's saying.

 

However he has got something of a point because there are non stoiciometric compounds where the ratios are not exact numbers, for example FeO practically never has exactly the same number of oxygens as iron atoms.

 

Very interesting. I didn't know that.

 

Like I said, I'm weak in chemistry. So, I'm not trying to dispute the atomic model in any way. I agree the evidence is overwhelming. But I think some of you are missing the point.

 

First, you refer to Duhem as "that guy" as if he were a crank on the sidelines. Not at all. He was a highly respected scientist at the turn of the 20th century. It is interesting to see how we learn our science history. Not too long ago I was in the same boat, where I didn't appreciate the extent of the debate over some of these issues. The textbooks only teach you about the winners, and we accept the winning models without question. We put the winners on pedestals (Dalton, Bohr, etc.) and forget the losers (Duhem, etc.).

 

Just don't forget that Newton was the accepted winner for centuries until Einstein came along.

 

I am some what confused. I do not see how his argument disproves anything.

 

Also the Atomic Model is very very old. It original proposed (very basically) by Democritus in 450 BC. The modern version was came into being in the early 1800's (Dalton's Model). And was proven by Einstein in 1905 in his Annus Mirabilis Papers. So I do not see how Duhem would not be aware of the atomic model.

 

Also Bohr did not do any work on the Law of Multiple Proportions. Most of his work was on the model of the hydrogen atom and working out the basics of Quantum Mechanics.

 

Maybe I was not clear. Duhem was aware of the atomic model. He was trying to refute it. And I mentioned that it was an old Greek idea. The thing is, the Greek model had supposedly been debunked (if I remember by history correctly) until it was revived by Dalton (At least I think the revival started with Dalton. You could probably find others between B.C. and the 19th century that played with the idea.)

 

I didn't mean to start a debate. I expected more people would have heard of this. But, I got my answer, so thanks.

[John Cuthber]

I'll be honest, I called him "that guy" because I couldn't be bothered to cut and paste his name, and I can't spell. It's a comment on my laziness, not his standing.

[Resha Caner]

And I didn't mean to sound ungracious. I appreciate your help, and enjoyed the discussion.