I am wondering about the meaning of word "arguably". I have of course read its definitions in dictionaries but they seem to differ.
As I am from Poland, I checked English->Polish dictionaries in the beginning.
Some of them say that "arguably" = "bezsprzecznie", which in Polish means that "something is sure and you shouldn't even discuss about it", I'd say that "unquestionably" would be a synonym.
Other say "arguably" = "prawdopodobnie, możliwie", which in Polish means "probably, possibly".
Those definitions didn't really seem to be similar to me, so I decided to look up definitions in English to English dictionaries.
1.susceptible to debate, challenge, or doubt; questionable: Whether this is the best plan of action or not is arguable.
2.susceptible to being supported by convincing or persuasive argument: Admirers agree that it is arguable he is the finest pianist of his generation.
To me, those meanings seem to be contrary as the first one is "you can have doubts about something" and the other is "you shouldn't have doubts about it, because the convincing argument exists".
as may be argued or shown by argument
It seems to cover the second meaning from dictionary.reference.com.
I also checked the meaning of "argue" in English->Polish and it seems to mean "disagree about something" as well as "give a proof" (in formal, mathematical sense).
My problem seems to be that I don't know if 'arguably' in sentence means that the fact mentioned in that sentence is:
'sure', 'can be proved', 'you shouldn't have doubts because everyone knows that this is true',
'you can argue about it', 'it's one of possible options', 'it's just my opinion'.