Does scientific knowledge of English help in learning other languages , like scientific knowledge of Sanskrit makes it easy to learn Hindi , Gujarati and scientific knowledge of Arabic makes it easy to learn Urdu ( which is basically Hindi but it has different letters ; correct me if I am wrong but this is what I have heard )...like English obviously does not help much in learning French , Spanish or german but if we learn French , it becomes more easy to learn Spanish . By the way , I am bi-linguist (Hindi and English)...just wanted to know the extent to which a good knowledge of English will help me to learn a Language (I just want to learn 1 more language to set myself apart from rest of Indians who also are mostly bi-linguists).Can you tell me the language to which English relates the most ? Sources of this question -: my mind , another meta question ( pragmatic benefits of English language ) and auto biography of mahatma Gandhi (scientific knowledge of one language helps in learning other languages)
Firstly I should say that I write this as someone for whom English is the first language. People from other countries may have a different view.
I take it that by scientific knowledge you mean the analytical study of the structure of the language in which case the short answer is "up to a point".
In terms of vocabulary, English has borrowed words from so many other languages that it does not always help.
In terms of language structure, other languages tend to be more rigorous in their grammar and syntax. Also, you will find declensions and conjugations that either don't exist in English or do so only in a simplified form. However, the principles are transferrable.
I don't think that my knowledge of English has been of great help in learning other languages. However, the process of learning other languages is of great help in understanding all languages, including my native language. Your scientific knowledge of the language will help enormously when trying to make sense of a new language. You will know what to look for and how to use what you find.
I have been fortunate enough to travel widely. I can say that landing in a country where you don't know the language, nobody there speaks English and the alphabet is strange is a challenge. The fact that I learnt French and Russian at school enabled me to cope with Korean and Lithuanian, amongst others. I picked up the key elements by watching the television news.
So to return to your question, yes a scientific knowledge of English will help you learn another language. Not necessarily because it it English but because it is a different language to your own. Then, as others have commented, you naturally feed that back into your knowledge of English and all the other languages that you know. From my experience of travelling in India, I believe that the widespread Indian experience of speaking local language, Hindi and English means other languages will come more easily.