Byrne: One of our club' s bylaws specifies that any officer who fails to appear on time for any one of the quarterly board meetings, or who misses two of our monthly general meetings, must be suspended  Thibodeaux, an officer, was recently suspended  But Thibodeaux has never missed a monthly general meeting
Ttherefore, Thibodeaux must have failed to appear on time for a quarterly board meeting
takes for granted that an assumption required to establish the argument's conclusion is sufficient to establish that conclusion