Films worth arguing about afterwards
The good ones ask, they do not answer
A film that lectures you leaves nothing to think about; you either agreed already or you did not. The films that stay with you set up a genuine dilemma, give the opposing position its strongest form, and then decline to tell you who was right.
That is why so many of them end abruptly. The last scene is deliberately the beginning of the conversation rather than the end of the story.
Ideas need a story to travel in
The trap in this category is the film that is only a thesis — characters as mouthpieces, situations engineered to prove a point. It reads as clever for twenty minutes and hollow for the remaining hundred.
The durable ones smuggle their questions inside something that works as drama on its own terms. You could watch them without noticing the argument, which is precisely why the argument sticks.
Do not watch these tired
More than any other category here, these films punish a half-present viewer. They tend to be quiet, dialogue-led and structurally patient, and a tired audience reads all three as boring.
Watch one when you are sharp, and if possible with someone who will disagree with you. Half the value of this list is in the hour after the credits.