It´s been further discussed the way in which we have to call the language spoken in Spain and most of Latin America. If we pay attention to the etymology of the two available terms, namely español and castellano, we find that the former refers to Spain and the ladder to Castile (also in Spain).
Nowadays, castellano is used more frequently to refer only to the language as spoken in Spain, and español to the language as it is spoken in Latin America.
However, there is something hidden behind this distinction. If it were all about a title, it wouldn´t be necessary to get to an agreement about it just as there is no discussion about whether to call table “a table” or something different. So, why is it so important?
The thing is language is much more than a mere tool to communicate with each other but it is rooted so deep inside us and it is such a part of us that it becomes very hard to take distance from it and grasp its nature in all its complexity.
Language is also a flag. With this, I mean that the specific way in which a community (I am purposely avoiding the word “country” ) speaks is a symbol of the community itself, and its members can identify themselves as belonging to that community because (among other things) they share its dialect: Women don´t speak like men, children don´t speak like adults, country people don´t speak like city people, high class people don´t speak like low class people, Spaniards don´t speak like Peruvians, Spaniards don´t speak like other Spaniards, and so on and so forth.
The situation in Spain is the epitome of this. Why is that castellano is used to refer to Spanish as spoken in Spain? The reason has nothing to do with it being more appropriate in linguistics terms: it´s about the Basque people, the Catalans and the Galicians refusing to use the word español to call Spanish since they are Spaniard people too but they don´t speak the same language. So, the fight on the terminology arena is a political fight, in the first place.
If we examine the history of immigration, we will come across many other examples: millions of cases in which a certain group of immigrants wouldn´t speak their language, they wouldn´t encourage their sons and daughters to use it because it meant a shame to come from wherever they´d come from.
When it comes to language it is never really about grammar rules and vocabulary but about people.
If someone asked me how I´d call the language I speak, I´d answer that I speak Argentinian or even better: a femenine educated middle class variation of Porteño (which is one of the many dialectal variations of Old Spanish), slightly affected by the five years I spent in Entre Ríos province but considerably influenced by me being a Liberal Arts student…
…or I´d simply say that I speak español… or castellano… given that none of them fairly represents the reality of the language I speak.