I would take issue with only one paragraph in Mr. Parker's very well-thought-out and -stated essay. He writes:

For today's needs English is the only rational solution. If I were a Dane and my native language were Danish and if I had a child who I wanted to be able to take advantage of all opportunities which may present themselves, I would certainly advise my child to learn English. Esperanto would not be an option.

Of course English presents the best language-learning target, for economic and academic advanncement, for a random Danish child. However, the propaedeutic effect of learning Esperanto first makes the "Esperanto would not be an option" assertion false. If we're talking about formal language learning (say, in a school setting), there is a body of significant experimental evidence (not to mention tons of the anecdotal kind) to show that learning Esperanto for a while will significantly speed up the successful acquisition of English (or, probably, any other third language) later. English schoolchildren who took one year of Esperanto followed by three years of French scored better on French testing than a parallel group that took four years of French (and they had an additional language to show for it, one that would come in handy in many places where French would be useless). A similar study was done, with similar results, in Finland with Esperanto as a prelude to (I think) German. There have been other such studies. My essay "The Math Behind the Assertion that It Really Would Make Sense to make Esperanto the World's Default Second Language" lays the potential value of this advantage out in simplified-for-easier-assimilation "story problem" terms.

Haruo