How did dharmaśāstras develop? What are their sources and the people they address?
Timothy Lubin's presentation showed how they are intimately connected with Gṛhyasūtras (whereas he deems Śrautasūtras to be part of a different world). Gṛhyasūtra authors, Lubin maintains, already introduced many concepts which later became crucial for Dharmasūtras. Among them, he focused on ācāras and on the way social duties are differentiated. It seems that the differentiation among Brāhmaṇas, Kṣatriya and Vaiśya was already current in the Gṛhyasūtras, with the first one as the default category, and the others defined through their differences with it.
ācāra seems to gain an increasing importance, with Dharmasūtra texts which show an increasing openness, accepting yathācāram 'according to custom' as a possible option. In a text mentioned by Lubin, after various options even yathākuladharmam 'according to one's family dharma' is presented as an option.
When it comes to their realm of competence, even women are mentioned as authorities. And, only in Dharmasūtras, even śūdras might have a certain authority in specific cases. Interestingly, the rules known from śūdras and women are not defined ācāras (a term which is only reserved to śiṣṭas).
Why this increasing openness? Possibly because, in comparison to Gṛhyasūtras, Dharmasūtras try to make more and more room for elements that do not fit in the śiṣṭa-defined world-view. Hence, they need specific sources for that. These sources might be the śiṣṭas, i.e., the Brahmins imbued with the Veda, so that they are reliable, their ācāra `custom', but also the behaviour of other groups, if one needs to rule a field where there is no śiṣṭa-rule at hand to apply.
DELENDA CARTHAGO: Japanese scholars read their papers, but at least distribute the written version, so that one can follow it. I tend to think that one should 1. avoid reading, 2. at least "recite" one's written text, 3. if none of the above is possible, at least distribute the written text.