Ross considers the nature of moral knowledge in different places, that is, right and good and the foundations of ethics. He believes that the acquisition of moral knowledge is comparable to the acquisition of mathematical knowledge, because in both mathematics and ethics we have certain crystalline intuitions from which we construct everything we can know about the nature of numbers and on the nature of duty. (1939, 144) In what follows, I will elaborate the key elements of Rossian moral epistemology, that is, the ideas of evidence, fallibility, justification and their relationships will be studied in detail. To clarify the notion of self-evidence, I will discuss the relationship between the justification of self-evident moral propositions and “further reflection” within the Rossian framework. I believe, as many contemporary Rossian moral philosophers also do, that there is no necessary connection between evidence and evidence. There are, as I show, some obvious propositions that require further consideration to be justified. Moreover, it does not follow from Ross's theory that self-evident propositions are infallibly true; on the contrary, some obvious propositions (prima facie duties) are fallible and may be false. In this way, I use two terms for further elaboration of this idea; that is, obviously justified and obviously true. After that, I will examine Ross's idea of ​​evidence and his theory of justification. To do this, the idea of ​​modest foundationalism will be discussed. Finally, I will address the question of particularism in real duties and generalism in prima facie duties.2.2.1. Belief about prima facie duties and actual dutiesIn this section, I will first discuss two types of beliefs in Rossi...... in the middle of the article...... cal process, we understand the generality of prima facie moral truth when we see some particular moral cases. But this is not a deduction, it is intuitive. In other words, it is not important to know the number of individual cases where, on the face of it, a promise was kept, because this method is not enumerative. Finally, as Stratton-Lake says, Ross does not make it clear what it means to say that moral principles are self-evident, but it is somehow clear what he does not mean. He argues that an obvious proposition is not necessarily an obviously true proposition (1930, 2002, 29). Nor does he say that an obvious principle is one that is not subject to serious debate. He believes that we have direct knowledge of self-evident moral principles, that is, knowledge that often cannot be derived, but in some cases could be derived from an even more fundamental belief..