[magpi3]

You're just playing with semantics. If everything humans do is natural than everything is natural: computers, plastics, concrete, etc. The purpose of using the word natural is to distinguish from what is unnatural, and without grabbing a dictionary, for me that generally means something that does not "naturally" occur (i.e. without human intervention specifically) in the natural world.

Chemical engineers create unnatural things, things that don't exist in the natural world.

[drdaeman]

That's the whole point. Word "natural" is not good in any serious argument because it simply doesn't have well-recognized unambiguous semantics most people can agree on. Ask a bunch of folks if some things are natural and while they'll most likely agree on the basics (wild forest flower is most likely would be called "natural", while a mobile phone is most likely not) the opinions will start to diverge on less obvious stuff (e.g. penicillin).

It's like a concept of "god" - everyone has their own idea what it might mean. (full disclosure: I'm ignostic).

With such words it's best to either start with a definition, or pick some different, less ambiguous term.

[ludston]

I disagree. It's easy to choose this as a position if you intend to argue disingenuously, and therefore you always ensure that your argument positions are logically sound, and complex and abstract enough so as to exclude most others from being able to argue back. On the other hand, if you are steel manning the other person's argument, instead of playing a complex word definition game that invalidates what they've said on account that they haven't explicitly defined for you all of the axioms of their position, (and if they did you can attack their argument with a different set of nit picking fallacies such as "too long didn't read"), you would probably find their argument compelling, or at the very least you would be forced to reveal the true reason you disagree with them. It's much easier to attack somebody else's argument for using the wrong language than it is to present your own position.