Well, the obvious answer is to tell him no one will shop at his bookstore if they don't know that it exists. But bosses, especially of Ye Elder Persuasion, tend to be resistant to new modes of moolah-making. Here are some options to help sway him in the direction of our brave new world, otherwise known as Teh Intertubes.
Appeal to his common sense
And by common sense I mean wallet. Does he want to make more money? Then he needs to attract and retain more customers. He might've had some luck in the past with walk-ins, neighborhood reputation, or the simple act of being around for a long time, but this is no longer how business is done or information is spread. According to a 2011 MerchantCircle report, nearly 37 percent of small businesses named social networking profiles as their most effective marketing method, second only to search engine marketing. Neither of these tactics exist in the local Penny Saver.
Appeal to statistics
Whether your boss likes it or not, social media dominates the world we live in. It's where the people are. People who want to spend their green on yer 50 Shades of Grey, if you catch my drift. Speaking of porn, did you know that social media has overtaken porn (!!!) as the No. 1 activity on the web? Porn!
Some numbers: 172 million different people visit Facebook every day, 40 million use Twitter each day, 22 million are on LinkedIn. The platforms are there. The people are using them. The platforms are also efficient and cost-effective, which is to say, free, as we've talked about before. I challenge your boss to find an article from a reputable source that says having an online presence hinders business.
Appeal to the masses
People are far more likely to rely on the feedback and referrals they receive from their friends and followers than they are to paw through a phone book, which is, let's be honest, at the ass end of the recycling bin before it even enters our homes anymore. According to Nielsen, 90 percent of consumers trust peer recommendations, but only 14 percent trust advertisements. Social media also makes "word of mouth" marketing and friend recommendations easier. For instance, if I see on Facebook that my neighbor, co-worker, and random one-night stand all like your bookstore, I'll probably be compelled to look at your page, simply because I have friends who like your bookstore. Also, again, it's free advertising! Your boss literally has nothing to lose, except maybe a few hours of time per month.
Appeal to his duty to his customers
The best way to get real-time feedback from people is to ask them online. Want to know whether your store should carry more 1970s-era Communist erotica? Want to find out how customers found your store? Want a way to advertise readings and community events? Want a cookie? All of this can be accomplished swiftly and easily on social media channels. Well, except maybe that last one, but even then, you'd be surprised. Twitter is remarkably effective at fulfilling short-term needs.
Appeal to his vanity and fear
It's a cut-throat world out there, especially for indie bookstores. I guarantee that most or all of his competition is using social media. Take a few minutes and show your boss what the competition is doing online. Odds are this will light a fire under his ass. If not, then ask him whether he would want to start a race with his foot tied to a tree? Not for fun, but as a compelling visual metaphor. But also for fun.
Appeal to his ego
I've found that old-school types tend to be resistant because they don't understand how new technologies work, and they don't want to appear foolish. If you're feeling charitable and industrious, spend an hour and create a Facebook page for the bookstore yourself. See whether you can get 30 people to "like" the page in a day. I bet you can. Sometimes the best way to persuade someone that something has value is to prove it. This, unfortunately, involves more work for you, but it'll make you look like a go-getter, and a stellar employee with "RAISE" written all over you, so there's that.
If the bookstore has a Yelp page, show him the results of that. Show him what people are saying about his bookstore online (hopefully it's mostly good things, but if not, that tells an important story too). Seeing how his brand is faring might be all the proof he needs that people care about his store and that there's a whole world of untapped potential customers awaiting him.
Also, have him watch this Socialnomics video. It's great: