First of all, if you desire to follow a moral code which prohibits murder more than you desire to murder, then you do not want to murder, any more than if you desire to buy a candy bar for $1 if want $1 more than you want the candy bar.
Now, consider the class of rules that require maximizing a weighted average or sum of everyone’s preferences. Within that class, ‘do not murder’ is a valid rule, considering that people wish to avoid being murdered and also to live in a world which is in general free from murder. ‘Do not seize kidneys’ is marginally valid. The choice ‘I choose not to donate my kidney’ is valid only if one’s own preference is weighted more highly than the preference of a stranger. The choice ‘I will try to find the person who dropped this, even though I would rather keep it.’ is moral only if the preferences of a stranger are weighted equally or greater to one’s own.
First of all, if you desire to follow a moral code which prohibits murder more than you desire to murder, then you do not want to murder, any more than if you desire to buy a candy bar for $1 if want $1 more than you want the candy bar.
Now, consider the class of rules that require maximizing a weighted average or sum of everyone’s preferences. Within that class, ‘do not murder’ is a valid rule, considering that people wish to avoid being murdered and also to live in a world which is in general free from murder. ‘Do not seize kidneys’ is marginally valid. The choice ‘I choose not to donate my kidney’ is valid only if one’s own preference is weighted more highly than the preference of a stranger. The choice ‘I will try to find the person who dropped this, even though I would rather keep it.’ is moral only if the preferences of a stranger are weighted equally or greater to one’s own.