Some ameteurish science:
I started up a new fort with vanilla raws with the intention of focusing on scholar visitors. I embarked with four knowledge-skill dwarves (an astronomer/geographer, a logician/mathematician, a chemist, and an engineer) and set up a large, smoothed, furnished library and refrained from establishing an inn or temple. The moment I appointed the scholars to the library I got a Historian visitor, and a steady stream of scholar visitors followed for the next year. Because my citizens were beginning to get distracted from boredom and impiety, I set up a very minimal tavern and ecumenical temple. The former immediately started attracting poets, bards, and dancers, to the point that within a few months the number of "tavern" visitors and "library" visitors was approximately equal, despite the fact that it had taken the high-quality library some time to accumulate that population. Once I added some rentable rooms to the tavern, mercenaries and performers requested residency much more frequently than visiting scholars - I approved scholars only. Judging by the quality of their writings, many of the visiting scholars were quite skilled ("overall, the prose is great") but most scholars that applied to stay were Adequate/Competent only in their disciplines - with the exception of several elven Great Geographers who seem to be from the human-conquered elf civ to the north (who are all >180 years old).
Findings:
- I've seen the following job titles: Historian (unknown skill), Naturalist (Tracking), Geographer (Geography), Chemist (Chemistry), Mathematician (Mathematics, possibly Logic), Engineer (Optics, Siege, or Fluid Engineer, Mechanic), Doctor (medical skills, esp. Diagnoser), Astronomy (Astromer). Reading, Writing, Wordsmith, Student, Teacher, and Critical Thinking appear to be secondary, but related, skills, which are associated with the "Scholar" title.
- Taverns accumulate visitors (and attract residents) much faster than libraries in general. Temples of No Particular Deity do not appear to generate visitors at all.
- No furniture is required for a library to function - an empty room designated as ones still allows appointed and visiting scholars to Discuss research concepts.
- Tables, chairs, containers, and scrolls/quires are required for original writing (which visitors seem to do more frequently than residents) and scribe-copying.
- Bookcases do not appear to be strictly necessary to library function, but like cabinets, they reduce item clutter.
- A library with no scholars
will may not (thanks PatrikLundell) attract visitors, but it will store preexisting codicies and scrolls, where citizens will read them. - Possibly by merit of their long lifespans, desire to wander, and dreams of seeing the great natural places of the world, elves seem predisposed toward acquiring high Geography skill levels.
- Similarly, dwarven visiting scholars are often some form of engineer (Optical, Fluid, or Mechanical), a discipline that
does not appear is rare among humans or elves. Mathematics and Logic also seem to be primarily dwarven disciplines. Dwarves constitute a majority of scholarly visitors - whereas Performers and Mercenaries are a roughly equal mix of elves, dwarves, and humans. - Human scholars seem rarer in general, but this is likely affected by the randomly-generated ethics of nearby human civs in my world. They have good relations with my civ, but they keep elven slaves.
As an addendum, I'll add that this fort is the first non-worldgen gameplay in a 350-year-old world, so I can't answer the original question of this thread definitively. BUT: several years in, my fortress is attracting a lot of baron(esse)s consort, who generally have Novice-ish skill levels in knowledge skills. This only started occuring about 7 years into the library's existence, and they've been arriving about once a season since. I speculate that these learned consorts are arising organically through post-worldgen interactions, since they are historical figures and therefore more likely (I think) to obtain written works tracked by the game engine. Oddly, it's
only baron-level consorts; no count or duke consorts, and no human nobles, even as non-library visitors.
It seems that the game doesn't create visitors from peasants - they tend to have an ordinairy career first, and then somehow decide to become scholars/mercenaries/performers (as is often chronicled in the codicies performers carry). At the fort level, this seems to occur because dwarves are constantly observing (and thus learning) performances in their social areas, and some will spontaneously read for fun without any knowledge skills - but I doubt distant sites are resolved well enough for this kind of thing to happen globally.
If I (or someone else) can find a codex describing the career change from a "job" profession to a "visitor" profession that was written after the world stoppped generating, that might provide us with some answers on whether visitors arise then.