Do good and evil exist?

In my view the best element of any Kubrick movie is how Kubrick presents questions, but not answers. Most films, even good ones, propose a question and then answer it, giving the perspective of the creator.
But Kubrick on the other hand simply proposed a concept and left it there, and in my opinion, 'A Clockwork Orange' asks us 'do good and evil exist?'
Are they real things that influence our actions? Or are they concepts we created to justify our choices?

At the beginning of the film Alex is an out-and-out villain, who can only be described as 'evil'. He's a foul, cruel, sick person with a twisted mind.
Then he undergoes the Ludovico Treatment, and emerges as a 'good' person... or is he simply mentally crippled? If he can't defend himself against the real evils of the world, how can he ever hope to survive?
When he meets the old man he abused earlier in the film, the old man takes him in and helps him, giving him food, a room, a shower, etc... but once he realises Alex wronged him in the past, he too becomes 'evil' and tortures Alex with music, tormenting him to the point Alex attempts to commit suicide.
After Alex recovers in hospital, we find he's back to his old ways. The ending is the most vague part of the film, like most of Kubrick's work, but I view this as the programming being undone, the treatment being reversed, and Alex returning to his old ways.

So the question raised is, are good and evil actual things that control our choices? Are we Jekyll and Hyde? Or are we Dorian Gray, perched on a sliding scale of grey, from light to dark but never in absolutes?
Do good and evil exist or are they concepts we impose on ourselves and others?

Food for thought.