I'm not sure if there's an absolute scale, but you can't deny that some languages have more complex grammar than others. Conjugating verbs is a good example: coming from a Latin language, English verbs are almost trivial, but I doubt that the reverse is true. If you wanted, you could put together a list of criteria, such as complexity of grammar rules, how common exceptions are (very common in English, for example), whether the writing is phonetic or not, etc. etc., which should give a rough basis to compare languages.
English has a comparatively simple grammar (at least in terms of things like verb tenses), but then is complex in other ways (size of vocabulary, modal verbs, noun affixes, idioms). We notice the complexity of other languages’ grammars because that’s the thing that stands out when we try to learn them, but people coming from other languages to learn English will be tripped up in other ways.
English is not my native language, and I agree completely - it's easy to pick up the basics (in terms of grammar and basic vocabulary, at least) but difficult to master (irregular pronunciation, idioms).
On the other hand, you might have a language with difficult basics, but relatively simple mastery once you have the basics down - I don't know enough languages to give an example, but it seems plausible.
So, yes, you'd likely get different results if you're comparing languages at different proficiency levels, but a rough comparison should still be possible.
"On the other hand, you might have a language with difficult basics, but relatively simple mastery once you have the basics down"
My impression, as a native English speaker who has learned German, is that German is much more like this than English. You have to know quite a bit to say fairly simple sentences. But once you know the basics, there are only a couple of advanced concepts to get you to mastery.
I'm not convinced by this. If you're just aiming to communicate in German, you can ignore noun gender, valency, many tenses, etc. It's all stuff you'll need to come back and learn later.
[maybe this depends on how you learn. My approach was, roughly, first learn to communicate, then learn to communicate correctly]
That's not the point. The point is that in order to communicate simple things correctly in German, you need to learn a lot more than to communicate simple things correctly in English. But to have correct mastery of German, it's not a large jump from there.
It seems like you're saying, once you've gone through 90% of the effort to learn a language, you've only got 10% left (as opposed to 10% for basics then 90% to master).
Yes, that's right, except for the important part. I'm sure the percentages are off, but here's the basic idea:
To correctly form simple German sentences you need to learn 90% of the non-vocabulary elements of the language. To get to mastery, you have to learn the other 10%.
To correctly form simple English sentences you need to learn 10% of the non-vocabulary elements of the language. To get to mastery, you have to learn the other 90%.
Sure you can deny it. You picked the classic example of something that seems hard to you because of your native speaker bias. What some languages resolve with conjugations and declensions, others resolve with combinations of prepositions and word order. English verb-preposition combinations are so brutally hard for foreign speakers to master that they publish "collocation dictionaries" to help. Latin's case system is much more predictable and regular, in some ways it's easier to learn.
Ranking human language complexity is a much more difficult task than you might imagine.
My native speaker bias for which language? :) I'm not a native English speaker, although I did learn it young, which I'm sure helped.
Still, my native language is Romanian, and I found English verbs easier to learn than French conjugation, even though French is very similar to Romanian in the first place.
Ha, I would have thought you were a native speaker, your English is excellent. :-) I think you make the same generalizations about Latin that native English speakers often do, though, in assuming rich nominal case = complexity. The issue is much more complex than that.
