18th century philosopher David Hume developed a moral philosophy that basically aimed at accounting for the source of our moral ideas such as good, evil, vice, and virtue. He thought that there are two alternatives: Morality is founded upon either reason or sentiment (Hume, 1983, 13). He argued that our moral beliefs are based on our sentiments that he thought essential to human nature. So according to Hume’s moral philosophy, when we judge, for instance, that a particular action or a person is just, this moral judgment is an expression of our feelings of approbation towards the action or the person. I argue in the first part of this paper that Hume’s moral philosophy falls short of laying the basis for an inclusive moral dialogue among moral agents who do not share the same set of sentiments towards a certain action or character. To make this clearer, think of a society in which everyone has a sentiment of approval towards a certain type of action. We know that the social structure one is raised in has a huge influence on her affective responses to morally relevant situations. But suppose that another moral agent who is from another culture where a sentiment of disapproval is elicited by that type of action enters into that society. So she disagrees with them over the moral value of that action. The question here is whether she can also enter into an inclusive moral dialogue with them. I argue that if we characterize the way we form our moral beliefs in the way Hume characterizes them, it is hardly possible for them to engage in an inclusive moral dialogue. The reason for this is that since according to Hume the source of our moral judgments is our sentiments, when we engage in a moral dialogue, we are basically citing our sentiments to each other. Once another moral agent does not have the feeling we as a community have towards an action, we can do nothing more than indicating that we feel differently than she does and she is eventually excluded from the moral dialogue among us. In the second part, I argue that the 18th century philosopher Immanuel Kant’s moral philosophy can provide us with a ground on the basis of which we can enter into a moral dialogue that does not exclude any party just because she is from a culture in which individuals are socialized to develop a certain sentiment towards a certain type of action. The clue for this argument is Kant’s idea that reason can be practical of itself (KdpV, 5:27). Part of this idea is that a purely rational moral agent is an agent who acts and justifies her actions without appealing to any empirical condition but only to the moral law. So a moral agent is a rational moral agent insofar as she justifies her actions in terms that can be endorsed by all relevant parties, not through a set of sentiments that cannot be expected to be shared by all in a morally significant situation. Therefore, moral agents do not cite their socially based affective responses to each other and they are included in a moral dialogue as long as they justify their judgments as rational agents. In a moral dialogue where parties are not expected to converge on a moral sentiment but reason in terms of mutually endorsable principles, no one is excluded.