If I my question is about a certain book by an author, should I use the tag for both the book and the author? Or just the book? What's the purpose of these author tags in the first place and when can I use them?
Let's think about this practically. If a Shakespeare expert comes to our site and wants to find questions about Shakespeare to answer, do we want them to be able to find all those questions in a single list, or have to search the title of each play individually? Ditto with Edgar Allan Poe, or Thomas Hardy, or Jane Austen, or many other authors one could mention. In many cases, people tend to be experts in authors rather than in any specific one of their works. When did you ever hear about an expert in A Winter's Tale, or in Pride and Prejudice, as opposed to a Shakespeare or Austen buff?
There are, of course, other cases for which the opposite is true. An expert in Sherlock Holmes stories wouldn't necessarily be expected to know all about The Lost World. Obviously individual work tags have their place here too. But I don't think we should get rid of author tags on the grounds that they're redundant: they aid searchability and might act as a bat-signal for experts, and both of those are what tags are supposed to be all about. Yes, there will be a lot of questions which have both an author tag and a work tag, but that doesn't have to be a problem. Until and unless it becomes one, let's allow the tagging system to grow organically, and see which tags come out on top.
Yes, let's have author tags.
We have five tags per question, even if every question is tagged with both and some books have several authors there is still enough room, so let's not artificially constrain ourselves before we have any clue how that tags will be used in practice.
Other answers already explain neatly why one would search for author tags to find every question associated to any of his or her works. I'd even go farther and say, edit them in. Those author tags only get really useful if the questions are tagged with them, so add those author tags if the question is missing them.
I think, for searchablility reasons we should encourage tagging title and author, not just the big/known authors. Especially small authors, which haven't got much attention will be easier to find for people, when we inckude them in the tag. Also, that is how other SEs like 'Scifi' do it.
I'd have them, encourage them for they will make searching easier.
Please note that I've written my answer as if the question is asking about requiring author tags on questions.
IMHO Author tags should only be used when the question is about the author in relation to their work.
Requiring people to tag every question with the author, or authors, of the work is a waste of time. It's also not always clear which author/s should be tagged.
For example, the Animorphs series was ghost-written by a lot of authors. Do I need to tag ALL of them when I ask about the series, or should I only tag them on specific books? Or should I not tag them at all and only tag Applegate?
I think another example is 39 Clues. It has several authors across the series. How should we tag those?
There are too many fringe cases to lay down an absolute for author tagging. If the asker wants to include the author(s), that's fine (as long as it's accurate), but requiring author tags on questions is, IMHO, not worth the hassle.
This is kind of a tricky question, and ultimately comes down to the use cases of tags. Tags exist in order to assist with categorizing questions for easy searchability. So, we have to think: when would someone search for an author? When would someone search for a book?
This doesn't give a very clear answer, and it's a little muddy. Maybe someone really does want to search for all questions about a particular author's books? But this seems more likely to me:
- You'll search the tag of an author if you want to find questions seeking answers that focus on the author.
- You'll search the tag of a book if you want to find questions seeking answers that focus on the book.
These two use cases can't coexist with a broader ability to search for every question about an author and their works, because there's a conflict of scope. However, it seems unlikely to me (or at least less likely) that someone would want or need a broader search of every question asked by an author, so authorial tags should be for questions about the author specifically. Here's how I see this working:
- Questions that focus on a specific book or story should only tag their question with that specific book or story.
- Questions that focus on a specific author should only tag their question with that specific author.
- Questions that blend these two (e.g. "What impact did [X event in author's life] have on the way they portrayed [event in story]?"), or require authorial context in order to understand the question, should have both tags.
That way, the two use cases above are satisfied. The third can still be done - it just takes some extra work.