In reply to the objection that there generally isn't enough time to calculate how a given act might affect the long-term general happiness, Mill sketches a kind of "two-tier" approach to ethics that accords an important place to moral rules in ethical decision-making. Mill argues that traditional moral rules such as "Keep your promises" and "Tell the truth" have been shown by long experience to promote the welfare of society. Normally we should follow such "secondary principles" without reflecting much on the consequences of our acts. As a rule, only when such second-tier principles conflict is it necessary (or wise) to appeal to the principle of utility directly.