The Mishna prohibits dancing on Shabbat and Yom Tov lest one come to fix a musical instrument.
According to the Tosafot, we no longer need to be concerned that dancing will lead fixing an instrument and the halacha should change accordingly and dancing should be permitted.
Here we have an example of a halacha whose original reason seems no longer to be valid, opening the question of whether the bottom-line halacha should be changed.
This series will focus on the approaches of the principal poskim to this question.
A source sheet is available through the links in both WORD format and pdf. In class we will translate and explain these sources.