You could suggest they go google their question, but this tends not to work out well. While you know the search query that would bring up links answering their question, and you know how to tell from the text snippets which links are probably written by sensible people, they don't have your context and background knowledge. They're likely to have trouble turning up anything relevant, and even if they do they probably won't find the arguments you were hoping they'd find. [1]

A better option is to quickly run the search yourself, find what you think they should read, and give them a link. (Ideally pulling out an excerpt to hook them.) If they're interested enough to go read a blog post this can be a good option, but it does have downsides. The biggest problem is that the post probably isn't a perfect fit for their question. Maybe it answers a very similar question but there are subtle details about the situation they're asking about that don't translate. Or maybe they're not starting with the background assumptions or values that the post was intended for. And generally a post is going to be on the long side, because it has to introduce and motivate the question.

The best option, if you're sure you understand the arguments yourself, is to buckle down and answer the question knowing that you're repeating things that have been said elsewhere. That's ok! Think of it like an offline conversation: someone asks something, you reply. This lets you answer exactly their question, and makes them feel like their questions are being taken seriously. I think of this as "instantiating the argument": you're forcing yourself to load the general argument fully into your head, so you can figure out exactly how it applies to the current situation. [2]

The biggest reason giving people custom responses, though, is that you're putting out text that you stand behind. If they have followup questions they know you're there to ask, and not just a blog post that the author may have moved on from, with a comments section thats long stale. At least in my case, the possibility of asking a question, even if I never ask anything, helps me be interested enough to really try to understand the evidence and arguments.

(This does vary with how much time you have, and how motivated you are to convince people. If you're overwhelmed with questions giving links may be the best you can do.)

[1] I think I remember someone else saying this, but I can't remember who.

[2] Giving a link to somewhere else is still good, especially if the argument is primarily associated with one source.