A William A. Garrigues is listed as one of the executive directors of the Philadelphia Anti-Slavery Society, in a 1838 book called The History of Philadelphia Hall.

http://books.google.com/books?id=cTUWAAAAYAAJ&dq=garrigues+anti-slavery&q=garrigues#v=snippet&q=garrigues&f=false

We don't know if this is our Garrigues ancestor. But an earlier William Garrigues had signed an anti-slavery petition, and the Garrigues family, as Quakers, would have been abolitionists.

Anyone living in Philadelphia in 1838 would have probably heard about or seen the anti-slavery riots that took place there that year:

http://www1.assumption.edu/users/mcclymer/His130/P-H/Grimke/PhiladelphiaRiotdefault.html

Two William Garrigueses listed in 1839 Philadelphia Directory: William Garrigues, Stonecutter, and William A. Garrigues, teacher.

By 1850, our William was listed in the Philadelphia Census with his wife and family as "constable."