# Was the Phlogiston Theory "Scientific?"

**URL:** <https://boards.straightdope.com/t/was-the-phlogiston-theory-scientific/596139>\
**Category:** Great Debates\
**Created:** [September 13, 2011, 4:54am UTC](https://boards.straightdope.com/t/was-the-phlogiston-theory-scientific/596139 "2011-09-13T04:54:22Z")\
**Posts on this page:** 2\
**Page:** 2

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**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\
**Post date:** [September 30, 2011, 10:59pm UTC](https://boards.straightdope.com/t/was-the-phlogiston-theory-scientific/596139/21 "2011-09-30T22:59:03Z")

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Joseph Priestley was a brilliant scientist. But he refused to concede the phlogiston theory was wrong, even when some of his own experiments provided evidence against it.

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**Author:** ![BarryB](https://avatars.discourse-cdn.com/v4/letter/b/d78d45/32.png) [@BarryB](https://boards.straightdope.com/u/BarryB)\
**Post date:** [October 1, 2011, 1:30am UTC](https://boards.straightdope.com/t/was-the-phlogiston-theory-scientific/596139/22 "2011-10-01T01:30:15Z")

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> [@Trinopus](#):
>
> I’m having a (friendly!) debate with a pal over this. He says the theory was not scientific, as it made no testable nor falsifiable predictions. He acknowledges that it is a fairly good (if naive) explanation of the process of combustion, but he says that the definitions of the terms – phlogiston is what is consumed in combustion; whatever is not consumed is not phlogiston – were circular, and thus not useful or functional in a scientific sense.
> 
> My opinion is that it was scientific, and did make specific falsifiable predictions – which is exactly why it was falsified.
> 
> (It wasn’t until people could burn fuel in sealed chambers, and weigh all of the combustion products, with very fine precision, before they realized that the process added weight to the fuel, rather than reduced it. Phlogiston wasn’t falsified, because it is very hard to “weigh smoke.”)
> 
> So…am I right? Or is my pal right? Or is it “more complex than that?” I thought about asking this in General Questions, since I think there is a yes/no answer, but I thought it belonged here, instead, because it gets a little messy, involving the definition of science, and some meta-issues about theories, etc.
> 
> Trinopus (also defends Freud)

To address his point directly, the definition isn’t circular since we know what combustion “is” (stuff burning), we can point to it and say “this is combustion”, so that when phlogiston is defined we have a starting point. If the only definition for combustion was “releasing phlogiston” then it would be circular.

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