Can I learn a violin without a teacher if I learn the scale and try to play it by ear?
There are some great answers here, but not yet from a violin teacher. As one myself, I'll try to give some perspective.Just like someone can theoretically learn how to be a skilled fighter pilot alone, including all the procedures and aviation protocols, it's basically impossible. Violin is in the same ball park. It's unbelievably complex and takes years of learning with a teacher to be even good enough to not have people cover their ears when you're playing (I'm not kidding).I saw this firsthand after my summer break from teaching. One of my more advanced students improved significantly from practice while a novice student had not only stayed the same, but had developed bad habits despite practicing much more than the advanced student. This had been consistent during my own violin learning path. There are many possible factors to this, one being that the advanced student has the experience to be able to recognize mistakes and correct them.The above shows that:Skilled violin players are able to learn on their own without going awryNovice violin students are not able to learn effectively on their ownSo obviously you want to get to the point where you're able to learn and improve your violin playing on your own. What does that look like in terms of years of playing? Well, the advanced student in question had 7 years of experience (with a teacher) and has a great ear. The novice student had been playing for 2 and a half years and also has a great ear. (Sidenote: Almost all my students have perfect pitch. It's something that violinists should learn over time)So what do I recommend? You have a few optionsLearn with a teacher for a few years until you are able to recognize correct your own mistakes during practice such as bow inconsistencies, intonation, and are musically mature enough to suggest changes to your interpretation to your teacher. For me, this came around the 8–9th year of learning. It may be different for everyone of course, but the key there is independent improvement.Learn with a teacher all the wayPlay the piano instead. It's much more “chill”.Violin really is one of the hardest instruments to learn. Good luck!