Final answer:
The colonists adopted "No Taxation without Representation" as they believed only their own elected legislatures could tax them, and that British Parliament's taxes without their direct representation were unconstitutional and a denial of their rights as English subjects.
Step-by-step explanation:
The colonists chose the slogan "No Taxation without Representation" because they believed that only their own colonial legislatures, which they elected, had the legal authority to tax them. The concept of direct representation was fundamental to the colonists' belief in their rights as English subjects, as it was enshrined in the Magna Carta and the English Bill of Rights. In contrast, the British Parliament, which levied taxes such as the Stamp Act, did not include any representatives elected by the North American colonies. Thus, the colonists argued that any tax imposed on them by a body in which they had no elected representation was a denial of their rights and equivalent to tyranny.
The British, who adhered to the idea of virtual representation, had difficulty understanding this concept because they believed that Parliament represented all British subjects, including those without the right to vote. However, many colonists firmly rejected the idea of virtual representation, asserting that only direct representation was adequate. Additionally, the colonists accepted Parliament's right to impose taxes to regulate trade, as they considered these to be external levies within Parliament's authority, but not taxes intended purely to raise revenues without their consent.