Yes spaceman18 but isnt it also the reponsibility of the operators and the aviation authorities to ensure that pilot do not fly when fatigued?
If a majority of pilots are flying when suffereing from excess fatigue, as the BALPA survey suggests, then surely there is something wrong with the system which is creating this situation?
You may be lucky enough to fly with an operator which is supportive and doesnt bend the rules. Some of your collegaues with other companies are not so blessed.
In summary - if only it was as simple as you naievly suggest!