One of the maxims or principles Sidgwick considers is that reason should never give way to Appetite or passion. In turn, he shows that they do not meet the four criteria. Sidgwick uses examples where reasonable people would have differing opinions about these maxims. He also puts into question whether they are clear and precise. I will draw attention to Sidgwick's argument pertaining to the third principle, that reason should never give way to Appetite or passion and his conclusion that it does not pass the scientific test.
On page 344-345, Sidgwick clearly states his disavowal of the third maxim mentioned above (now referred to as the third maxim). He writes "But if these rules are further understood (as they sometimes are understood) to prescribe cultivation of a habit of acting rationally; that is of referring each act to definitely conceived principles and ends, instead of allowing it to be determined by instinctive impulses; then I cannot see that the affirmation of this as a universal and absolute rule of duty is self-evidently true."
To support his argument, Sidgwick uses an example commonly witnessed where a reasonable person may agree that instinct may be a better spring of action then reason. On page 345, he writes "Certainly common sense is inclined to hold that in many matters instinct is a better spring of action than reason: thus it is commonly said that a healthy appetite is a better guide to diet than a doctor's prescription?"
Taken lightly, one may agree this holds true. However, with further inspection, I would argue that the reasonable individual would not agree. For it does not seem reasonable that in many matters instinct is a better spring of action then reason. Even if we act out of instinct, and it turns out for the b ...