Leaving aside whether there is really any answer to this hoary question, the trend for universities to create new departments and courses, and the preferences stated by college entrance exam candidates, are two powerful forces affecting department sizes.
姑且不論這個老問題有沒有答案，大學新增科系的走向與考生選填志願的取捨，是影響科系消長兩股銳不可擋的力量。