Parshas Teruma: Why we have an Adar Sheini

Before I start, I would just like to dedicate this post to "JL" and "Brother Ben". "JL", make sure you tell "Brother Ben" about this.

Okay, now that I've gotten that out of the way, here is the shiur.

In a nutshell, this shiur is just the Brisker Rav in Hilchos Kiddush HaChodesh 5:1.

The gemara in Sanhedrin 11a-12b discusses all the reasons why we are m'abir the year. The main 3 reasons quoted in the gemara is "aviv", "peiros ha'ilan" and "tekufa". The Brisker Rav explains that if we look at the Rishonim we see there is a fundamental difference in how to understand these reasons.

Shittas HaRambam

The Rambam on the other hand explains these 3 things as being centered around ensuring that Pesach falls out in the spring season and the lunar year match up to the solar year. "aviv" refers to the fact that it will still be winter, "tekufa" means that we want tekufas nissan to be after Pesach and "peiros ha'ilan" means that the fruits are not ripening on time. The Rambam refers to these reasons as "simanim", meaning that the main factor is that we want Pesach to be in the spring and the solar and lunar year to be in sync. The signs that we look for to tell us if this will happen are these 3 signs.

Shittas Rashi

Rashi on the other hand expains these reason as being 3 independent reasons relating to the 3 regalim. "aviv" refers to the fact that we want the grain to be ready so we can bring a korbon omer, "peiros ha'ilan" refers to the fact that we wantthe fruits to be ready so we can bring bikkurim and "tekufa" refers to the fact that we want Sukkos to fall out after tekufas tamuz.
According to Rashi, adding an extra month isn't just to ensure that Pesach is in the spring but rather we have 3 different reasons.

Nafka Mina

1) How many simanim do you need?

Rashi holds you need 2 simanim. The Rambam holds tekufa alone is enough of a siman but if you are using the other simanim then you need two. The reason is that according to the Rambam, these reasons are only simanim that he year is not in sunc. Tee siman of tekufa is a strong enough siman by itself. The other simanim are weaker and you need both of them. Rashi holds these 3 reasons are actual reasons and you need 2 reasons to add an extra month.

2) Adding a month during shemitta.

Besides these three reasons, the gemara lists certain tzarchei tzibbur which would allow Sanhderin to add an extra month. For example, if the roads need to be fixed up to allow people to be olah regel, you can dd an extar month. The gemara also says we don't add an extra month during Shemitta. The Rambam paskens that regarding Shemittah it depends why you are adding the month. If it is because of teh three main reasons, we add a month even in Shemitta. But if it is for tzarchei tzibbur we don't add a month.

The Brisker Rav explains that when it comes to ensuring the lunar year and solar year is in sync, so that supersedes Shemitta because that is a din. But when it comes to tzarchei tzibbur, just like we are m'abbir the year l'tzorech so too we can refuse to add a month l'tzorech and in Shemitta it is l'tzorech not to add a month (either so people can plant earlier or so there will be grain for the korbon omer).

Rashi who holds all the reasons are "tzorech" based, will tell you you can never add a month in Shemitta.

The Brisker Rav has a couple more nafka mina's ayin sham