I see enough ambiguity in the definitions to warrant the question.

To *dodge* someone|something is to avoid them|it because you don't want them|it to see you or accost you.

**We might dodge an organized crime "hit man", or dodge a question.** 

To *shun* someone|something is to avoid them|it because you have chosen to ignore or "turn your back on" them|it.

The difference lies in the motive and also in the manner. Dodging is done on an ad hoc basis, when the need arises. Shunning is planned and deliberate and ongoing.

**We might shun an acquaintance who committed a felony, or shun casinos.**

In Pennsylvania where I live (and elsewhere) the Amish, a religious community (who are portrayed in the film *Witness* by Australian director Peter Weir) will *shun* a member of their community who has committed in their estimation a very serious sin; they treat the person as though he or she did not exist.