Why did the colonists criticize the stamp act as taxation without representation?

The fundamental argument against Parliament's taxation was that since the colonies did not receive representation in Parliament, they should not be taxed. The colonists had lobbied for representation for years, without success. As a result, the sudden levying of taxes by Parliament was totally unexpected, and angered the colonists. Although the taxes levied differed, this was the fundamental argument for all of them, including the Stamp Act.