I spent some time practicing viola with a tuner this morning. I am playing a piece that spends a lot of time in the rather unpopular key of B major, so I thought it would be appropriate to use my metronome/tuner to gauge whether I was playing my B-major scales and arpeggios in tune or whether I was missing the mark. I usually trust my ears, but in this case (and because of this key) I thought I would give myself a little bit of help.
I found that in order to play absolutely in tune with the tuner (and make the little needle stop moving) in B major (where there are no open strings), I had to play with a sound that was totally devoid of character. It wasn't fun, so I stopped using the tuner.
It occurs to me that much of the string playing I love is filled with both character and expressive intonation. In these days of machines we tend to think that "the tuner" is correct, much like the way we used to think that the piano was always correct (which, with tempering, it isn't, but we adjust). Sometimes, particularly when interpersonal situations become tense and we are under pressure to be another person's version of "correct," we have to narrow ourselves to achieve our "goal." Sometimes we forget about the music.
Because of the way the modern flute is constructed, it is sometimes very difficult to play the instrument in tune. When I played the flute I found it very difficult to accept the intonation that was built into my instrument. After consulting with a bunch of singers (including Eleanor Steber, who taught one of my friends), I devised a way to open up my throat, lower my diaphragm, and play with a wide supported stream of air that would "find" the center of the pitch by itself. With practice I found that I could simply listen and the pitch would go where I wanted it to go, as long as there wasn't any tension in my tone production equipment that would stop the pitch from finding its natural center.
String players can do the same kind of thing (and in tense situations I need to remember this). The bow arm is analogous to the diaphragm, the bow hair moving across the string is analogous to the air itself, the fingers of the right hand work like the flute-players tongue, and the fingers of the left hand, with their various degrees of pressure and place, can adjust themselves in minute ways to allow a pitch to find its center and sound in tune, as long as there isn't anything getting in the way of the tone production.