Generally, when is it justified to play a string of notes and only use one down or up bow?
Example: Say the music wants you to play, b (quarter note),c (quarter note), and d(half note) to be played as a phase . Would I play those 3 notes using one bow action? How do I choose what notes get a full bow and what string of notes get a full bow?

That depends, usually, you don't get a full bow on a quarter not, unless the timing is too slow. half not can be a full if its on its original time value but if its a two-two time signature, i think thats a bit too fast for a full bow. Now, for phrasing, thats a whole different topic.

you said---Example: Say the music wants you to play, b (quarter note),c (quarter note), and d(half note) to be played as a phase . Would I play those 3 notes using one bow action? Yes, you have to play it in one full bow.

Thank you Charisma, for your answer. I need to learn all I can about bowing while playing phrasing. What if I had a string of 16ths notes and there was not any phrase markers. How would I know when to phrase? Inotherwords, how would I know how many notes to play using one bow action?
By the way, I read your profile (about me) and while I have a starter violin, I feel the same way as you do about my love relationships with the violin.

That's simple. a string of 16th notes is usually played one bow each note, that is, the faster the notes, the shorter the bow, the more pressure on the strings and more wrist action. you would only play a series of notes into a phrase (one full bow action) IF you see a rainbow-like line from the the first note (starting point of the rainbow) to the last note (where the rainbow ends). if you have any further questions, feel free to ask. I'll answer if I can.

Thank you again Charisma, for your reply. I do not have a violin teacher, and I am learning to play on my own. I am looking for a violin piece that has phrasing markings. Can you suggest something?

Try looking at Ave Maria: Gounod!

Also try Air on G String by Bach its full of phrasing!!! Enjoy learning!

Charisma thanks, I will check it out.

It all depends on what ganre classical music it is. Wether it medieval, baroque, romantic, etc.

Hope I helped,

mrviolin

Yea, that does help. Thank you Mrviolin