Slacktivism is given both more, and less credit than it deserves. For the slacktivist, it provides a simple way to take part in something larger than themselves. However, as you know, the conduit from liking something on Facebook to a mouth being fed, or medicine being distributed is usually quite tenuous.
In some cases, yes, slacktivists can have an impact. During the great heyday of SOPA, slacktivists did have some influence. Often the question comes down to scale; there is sometimes a tipping point. Not always, however, Kony remains a rapist and murder and warlord at large, but not all hype ends with such a fizzle.
With an eye to scale, you have to ask yourself how much is enough? Happily, the website TakePart has put together an interesting visual tool that will give you some appreciation of magnitude. We’re not saying that you didn’t already know that slacktivism is popular, but putting figures to intuition is always a good idea. Take a look (click for high-res):
Or, of course, you could do something that you know would make an impact, like donating to Doctors Without Borders. Now, get back to work.