Moral particularism is a theory in meta-ethics that runs counter to the idea that moral actions can be determined by applying universal moral principles. It states that there is no set of moral principles that can be applied to every situation, making it an idea appealing to the causal nature of morally-challenging situations. Moral judgements are said to be determined by factors of relevance with the consideration of a particular context. A moral particularist, for example, would argue that homicide cannot be judged to be morally wrong until all the morally relevant facts are known. While this stands in stark contrast to other prominent moral theories, such as deontology, consequentialism and virtue ethics, it finds its way into jurisprudence, with the idea of justifiable homicide for instance. In this case, the morally relevant facts are based on context rather than principle. Critics would argue that even in this case, the principle still informs morally right action.
The term "particularism" was coined to designate this position by R. M. Hare, in 1963 (Freedom and Reason, Oxford: Clarendon, p. 18). Within philosophy, the term is mainly used to denote a favoritism to one's own interests; which goes to say that morality is not universal.
Within traditional moral particularism it is strongly believed that moral thought has no distinguished structure. Some more extreme adaptations of the theory include the total rejection of theorized moral principles, as they are thought to be unnecessary in the presumed ordinary case of a relatively morally sensitive person being the one to utilize these principles. Often, the use of said principles is believed to be the contrary of effective, since moral particularists have faith in the subject of the presumed ordinary case to carry out whatever set of morals they believe necessary to the particular situation.
Jonathan Dancy argued that cases, whether they're imagined or otherwise, contain certain elements from which we can infer certain moral ideas.
A criticism of moral particularism is that it is inherently irrational. The criticism is that to be rational in relation to moral thought, you have to consistently apply that rationality to moral issues: but moral particularism does not do this.