Sherlock Holmes probably didn't think much about negativity.
Google's fabulous N-gram viewer shows use of the word in 1888 as less than .00001% in printed works, and its dramatic rise since the 1960s. It's definitely a term of the current age.
I bring it up, as I heard it used lately by someone who didn't want to truly discuss the topic at hand and proclaimed, "I just hate all the negativity!" Negativity is something you tend to hear a lot, if the thing you're in favor of is in the minority. People don't like what you like, and, thus, negative. But stating it that way seems like a sort of passive-aggressive blanket way of saying "All those people are wrong!" without coming out and actually actively disagreeing.
Case in point Holmes and Watson with Will Ferrell and John C. Reilly. As a fan of Will Ferrell movies, my reaction to the first trailer was definitely on the side of the angels. And when some folks I admire and respect jumped in immediately with "What a load of crap this is going to be!" I could go to shaming them for going negative, but I as someone who has enjoyed so many Will Ferrell movies that most people will declare stupid comedies, I didn't really feel they were over-reacting. Will Ferrell movies are something that a whole lot of people actually react very badly to.
Anger, hatred, disgust . . . all negative emotions, yes, but also part of the human systems designed to protect us. Sitting in a theater watching Holmes and Watson might seem harmless enough on the surface, but it could actually ruin someone's digestion following a good dinner . . . IF it's just not their kind of movie. Their revulsion at that preview is actually protecting them from potential harm, as minor as that harm might seem.
Yes, it's only a movie. It's not rape, murder, slavery, or any of those things we should be angry, revolted, repulsed, and driven to actively fight against. Going negative against bad things needs to be done. And if you taste some bad fish on your dinner plate, and your friend is about to take a bite, you might want to express your reaction to warn them off. And if someone else at the table, goes, "No, it's great!" then your friend is left to make their own choice.
Is the rise of the word "negativity" the sign of a rise in actual negativity? We see internet entertainers who base their entire focus on mocking things like bad movies. But pre-internet, we used to entertain ourselves for many an evening watching awful movies like Plan Nine From Outer Space and laughing at their flaws. I used to run a regular columnist in The Holmes & Watson Report who continually picked apart old Holmes movies issue after issue, but it always seemed like good fun. Of course, both of those situations were limited-audience affairs. Neither made it out to a world-wide stage where the actual fans of those things could go, "HEY! QUIT MOCKING MY FAVORITE MOVIE!"
The whole concept of negativity leaves us with a big question: Do we still get to go "Mazarin Stone sucks, and Conan Doyle really crapped The Strand on that one!" Or do we hold back, for fear of stepping on toes? Luckily, life doesn't always limit us to single actions.
You can scream at the gods at how awful "Mazarin Stone" is, if you feel the need, but knowing full well that damage could be done, listen for the gasps and yelps of the other diners in the restaurant who might have been put off by your outburst. And then speak more quietly as needed.
And maybe, then just to show you're not an ogre all of the time, start going on about how great "Speckled Band" is. There's good and bad in the world. Positivity and negativity. And the application of both, where needed is actually useful for keeping things running.
And while Sherlock Holmes never spoke of negativity, he did put a lot of stock in awareness. And trying to be as aware as we can is always useful in keeping those forces in balance. So, as always, let's try to be more like Sherlock Holmes.
(Except for those drugs, kids. Don't do drugs. Except appropriately prescribed by a doctor. Well, maybe unless the doctor is Watson and he's pushing brandy again. Aaaaa, figure it out for yourself.)