Rabbi Joseph B. Soloveitchik, a leader of profound influence in modern Orthodoxy in the United States, discouraged women from serving as presidents of synagogues or any other official positions of leadership, from performing other mitzvot (commandments) traditionally performed by males exclusively, such as wearing a tallit or tefillin. A minor reason argued for why only men wear tefillin is that the tefillin help keep men from thinking impure thoughts. Women are thought not to need help with this.) Soloveitchik wrote that while women do not lack the capability to perform such acts, there is no "mesorah" (Jewish tradition) that permits it. In making his decision, he relied upon Jewish oral law, including a mishnah in Chulin 2a and a Beit Yoseph in the Tur Yoreh Deah stating that a woman can perform a specific official communal service for her own needs, but not those of others.