Premise: A special celebration was planned for July 4, 1826 . . . it would not follow the usual style of "frying chickens, firing away damaged powder or fuddling our noses over tavern wine," as one newspaper put it. Instead, dignitaries who had taken part in the events of July 1776 were invited to Philadelphia for commemorative ceremonies. Ironically, Thomas Jefferson and John Adams, who had declined on that July Fourth, exactly 50 years after approval of the Declaration.
Hypothesis: John Adams declined to attend other commemorative ceremonies