What is the difference between Rule Utilitarianism and Act Utilitarianism?
Action is right as it conforms to a rule that leads to the greatest good, or that "the rightness or wrongness of a particular action is a function of the correctness of the rule of which it is an instance."
Person's act is morally right if and only if it produces at least as much happiness as any other act that the person could perform at that time
The supposed difference between Rule Utilitarianism and Act Utilitarianism
For rule utilitarians, the correctness of a rule is determined by the amount of good it brings about when followed. In contrast, act utilitarians judge an act in terms of the consequences of that act alone
The justification of action for the above rule mentioned are about the greater good of the society , How are Act Utilitarianism and Rule Utilitarianism different from each other ???
A rule utilitarian thinks, before acting, about the consequences of people following that rule. If the outcome is regarded as positive, she might decide that it's good to follow that rule in general, and will apply it in future.
An act utilitarian doesn't generalise the act, but regards it as a single action with a single outcome. She will have to weigh the possible consequences each and every time she acts.
Therefore, rule utilitarianism is considered to be more practicable, countering the anti-utilitarian argument that weighing each and every possible outcome each and every time is just not the way we want to (or can) spend our time.
On the other hand, act utilitarians consider rule utilitarians somewhat dull-witted, for a smart person might think of herself to be able to decide what to do without just applying rules time and time again. Also, blindly applying rules to specific situations can have unforeseen negative consequences that might have been averted by somebody who paid more attention instead of executing a programme.
At the same time, act utilitarians are criticised for their double standards, for they think it is useful if everybody follows "good" rules while they take for themselves the right to decide whether or not it is clever to stick to those rules in a specific situation.
An example: A rule utilitarian drives at night and sees a red intersection light. Thinking "it would have good consequences if people would stick to the rule and not cross red lights, so everyone is safe while waiting for a short while", she would apply that rule to herself and wait for it to turn green. Meanwhile, the act utilitarian might think "well, I certainly hope that people, who aren't me, in general follow that rule and stay put, but as there's no one around who might get influenced by my act, since there's no police around to fine me, and since I would see an approaching car as it's dark, I might as well cross right now."
Sources: There is a paper by Smart which you can find here; I'm pretty sure that's what we read in the seminar where I learned what I wrote. Smart's the act utilitarian.
Your example of the street light perfectly illustrates the difference(s) for me. Thank you for such an intelligible response. With there now being over 100k views of this post, I'm quite surprised you've only received [a net of] 10 upvotes (mine now included)!
Hi there, thanks! But the link seems to be broken, any chance you could update it, or tell us the title of the paper?