Final answer:
Act-utilitarianism is criticized for justifying actions that contradict common moral standards if they result in the greatest overall happiness, contrasting with rule utilitarianism and other more nuanced moral theories like pluralism, deontology, and virtue ethics.
Step-by-step explanation:
Many moral philosophers argue that act-utilitarianism conflicts with established moral norms because it allows for actions that are intuitively wrong if they produce the greatest happiness for the greatest number. For example, act utilitarianism might justify harmful actions like a vigilante taking a life or a jury wrongfully convicting an innocent person if it leads to a perceived greater overall happiness. This perspective of maximizing good on a case-by-case basis contrasts with rule utilitarianism, which suggests that adhering to rules that promote the greatest happiness in the long run is the best approach to morality.
Furthermore, critics like Sir William David Ross and Elizabeth Anscombe argue that utilitarianism oversimplifies moral life by reducing it to a single principle of maximizing happiness. They suggest that morality is more complex and that we need to consider a variety of moral obligations and factors. This is where pluralism and alternative approaches like deontology or virtue ethics play a role in offering a more nuanced understanding of morality that accounts for our common experience of ethical decision-making.