As far as I understand, cycles anti-aliasing in cycles (per default), works by sampling around a specific arc/vector determined by the camera position/rotation.
This explanation and my experience lines up with the answer here https://blender.stackexchange.com/a/3554/245 but kind of disagrees with the explanation given in https://blender.stackexchange.com/a/17845/245 specifically the image https://i.stack.imgur.com/irhyB.png describing sampling.
If sampling is working this way, the image will always be anti-aliased.
So my understanding for sampling is as follows
Where the radius of the circle is the width of the width value of the "pixel filter" in the UI.
This would mean however, that either not all the space is sampled or the sampled space overlaps (thus blurring the image) and the only way to get high quality (super-sampling) anti-aliasing is to manually render at increased resolution and downsample the image later. Is there a way around this?