Permitted or Pushed-Off

Rav Soloveichik sets up his second shiur in שעורים לזכר אבי מרי ז"ל, titled טומאת כהנים לשבעת הקרובים, with the concepts of הותרה and דחויה.

These concepts appear when a prohibition is pushed aside for the sake of a commandment:

• Hutra- the prohibition ceases to exist when the mitzva is possible. The act is completely allowed, and in fact it's a mitzva.
• Dchuya- the prohibition still exists, but while the possibility of the mitzva remains it is "pushed-off"

What is the Nafka Mina between these two approaches? The main nafka mina is the status of the issur once the mitzva is over and done. So for instance, can the Cohen wear the special clothing that he serves in, which are shatnez, when he's not serving in the Temple? The Rambam, who says Dchuya, says it's prohibited, while the Raavad, who says Hutra, says it's permitted.

The Mitzva of Burial

In this case, the Rav is talking about the two cases where a Cohen is obligated to participate in burying the dead, overriding his general prohibition from becoming ritually impure.  The Rav summarizes the 3 opionions of Rashi, the Rambam, and the other rishonim:

מת מצווה	קרובים	שיטה
הותרה	הותרה	רש"י
הותרה	דחויה
דחויה	הותרה	ראשונים
דחויה	דחויה	רמב"ם

Anyway, more to come, as the Rav then gets into some of the conceptual difficulties in the Rambam...