When Split was released, I was studying my Graduate Diploma of Counselling, and it seemed all of the lecturers and students had an opinion about how "damaging" the film was by portraying an antagonist with Multiple Personality Disorder [MPD]. Now, as of the time of writing (February 2021), MPD doesn't "officially" exist, in that most Psychology researchers, practitioners and workers know that it does exist, but there isn't enough peer-reviewed evidence for it to appear in the DSM-5. I've read an entire Post-Doctoral thesis on MPD, and I still don't really understand it, so I'm willing to give screenplay writers a bit of leeway, and, having watched the film a few times, I'm pretty sure Split isn't actually trying to represent MPD in any real way. Spoiler alert; The Horde is a supervillain and he has some kind of powers, so it's clearly not MPD in the same way that Venom doesn't have multiple personalities of any kind reminiscent of reality. Oh yeah, remember that Split is a backdoor sequel to Unbreakable? Because a lot of people were oddly mad about that at the time.
In all the jokes and memes, it's easy to forget that M. Night Shyamalan has made several really good films, Split being one of them. Split is tense, atmospheric and thrilling for most of the run, even in the closing segments where The Beast is out and displaying super-strength, bulletproof skin and wall-crawling powers. James McAvoy is brilliant as all 24 members of The Horde, even managing different mannerisms for most, and Anya Taylor-Joy does an excellent turn as Casey, blending strength and vulnerability better than most young actors in thrillers. Where Split does fall down though, is in its representations of Mental Health, not so much any conditions but in the practice and lived experience of those with a history of trauma. Throughout the film, Casey flashes back to her younger self, learning to hunt and suffering sexual abuse at the hands of her uncle, and it is through these experiences that she is able to survive captivity and the Horde. Quite literally in the climax.
The Beast's agenda, that only the "pure" can survive, turns out to mean that only those who have suffered are worthy of life, so when he sees Casey's scars, he backs off. Yes, it's the old token of "suffering makes you stronger" and, speaking as a Psychotherapist, no, trauma doesn't actually make you "stronger" in any sense. There are also concepts of Mental Illness giving a person superhuman powers, but that bothers me less, as it's essentially just The Horde to whom that applies, and the old chestnut of a therapist being more focused on their career than their client. Given that neither Split nor Shaymalan is unique in their unhelpful take on Mental Health Psychology, I really can't muster up much anger over it, though I can understand how some people get quite offended by it. As is, Split is a solid thriller, and I would like to see more films constructed around a super-powered antagonist menacing normal people. Someone like Deatwatch, Razorfist or the Dollmaker would be really interesting.
