By this reasoning, Robert Louis Stevenson, Jane Austen, Henry Fowler (author of Modern English Usage) and Wilson Follett (author of Modern American Usage) were also not competent speakers of English, since they all either use that construction or endorse its use. That's a pretty good class of lowlifes, and I'm happy to join their company.
E. E. Cummings also routinely violated the standard rules of English, especially those of capitalization. If you are so anxious to be lumped with your favorite writers, why not embrace his style?
You are confused. A definition is not a logical argument, and definitions are not in general the result of logical arguments; thus appealing to actual use cannot be a logical fallacy when determining a definition. Has a single dictionary or style guide endorsed your restrictive definition of "scientific"?
This is another straw man argument. I have never offered any definition of "scientific" (restrictive or otherwise). I have simply indicated that there were no scientists before 1834. How anyone can disagree with this obvious statement is, depending on my mood, either infuriating or laughable.
Even if we assume that natural philosophers could be considered the forerunners of modern scientists (doubtful), this explanation immediately runs afoul of multiple problems. Since the so-called "scientific revolution" is often considered to have been started when Nicholas Copernicus published
On the Revolutions of the Celestial Spheres in 1542-3, one would expect that Copernicus must have been a natural philosopher. Except, of course, that he wasn't. The next supposed actor in this scientific revolution is, of course, Galileo Galilei. We would expect him to have been a natural philosopher too, except, of course, that he wasn't. The final actor in this so-called revolution was Sir Isaac Newton. Thankfully we can at least say that he was a natural philosopher. Two out of three isn't bad, I suppose.
Of course all of this overlooks the important feature that all had in common:
They were all mathematicians. Of course, no one nowadays alleges that all mathematicians are scientists – and rightfully so. I am simply wondering what logical basis you have for your historical revisionism.
Even if you consider that science and empiricism are the same, then you cannot date science earlier than John Locke, who is credited with founding empiricism in 1689.