In order to give this seminal question a structured framework, the Sages formulated the “Ma nishtana” text, through which the children express their surprise at how different this night is, paving the way for the telling of the Exodus story. In the text of “Ma nishtana,” the Sages included questions about all of the Seder night mitzvot related to eating: matza, maror, the Paschal sacrifice, and the two dippings. After the destruction of the Temple, we no longer ask about the Paschal sacrifice and instead ask about reclining at the Seder.
If there are no children present to ask “Ma nishtana?” the youngest participant asks. Even if all the participants are Torah scholars well versed in the story of the Exodus, one of them must ask “Ma nishtana?” Even an individual performing the Seder alone must begin with “Ma nishtana?” This is how the Seder is arranged; we begin with a question because it makes the explanation more complete. Once a child or someone else has asked “Ma nishtana?” the other participants need not repeat the question and may proceed immediately to “Avadim Hayinu” (SA and Rema 473:7).
One authority writes that the mitzva de-Oraita to tell the Exodus story only applies when a child actually asks a question, but if the child does not inquire, the mitzva of the Torah is only to commemorate the Exodus from Egypt, though one is still rabbinically required to tell the story. This is the implication of Responsa Rosh 24:2, but this is not the view of most poskim. Rather, they maintain that there is a mitzva to recount the Exodus in all cases, and one who has a child is obligated to tell him the story, as the Torah states regarding the son who does not know how to ask, “Tell your child on this day: ‘It is because of this that God did for me when I left Egypt’” (Shemot 13:8). (R. Yeruḥam Fishel Perla, in his commentary on R. Saadia Gaon’s Sefer Ha-mitzvot §32, states that according to Ramban and other Rishonim, one who does not have matza is exempt from the mitzva of telling the story of the Exodus, based on the phrase “because of this” [“ba-avur zeh” – the Hebrew uses the demonstrative pronoun “zeh” instead of the expected indefinite relative pronoun, indicating that it refers to an object that is present, i.e., the matza]. Additionally, see Sidur Pesaḥ Ke-hilkhato ch. 6 n. 2 which mentions a distinction between a child who asks his father a question, which obligates his father to tell the story in detail, and a child who does not ask, which only obligates the father to tell the story briefly. We can explain that if the son asks, the father must embellish his response based on the question, but if the child does not ask, the father need only tell the story briefly. Embellishment depends on the child’s desire to listen and obtain answers. See SAH 473:42.) In any event, it is clear that at least on the rabbinic level one must recite the entire Hagada as formulated. Even if he is alone, he asks himself the questions (Pesaḥim 116a) and thus extends to himself the obligation to answer.