That some arbitrarily minimal amount of subjective pain can be presumed to be actually distinguishable from the general background unpleasantness of being human in the first place.
Edit: Rephrased to remove gibberish resulting from temporary brain/keyboard disconnect.
For some reason HN won't let me reply to Houshalter's post, but...
> objectively
How can pain be objective? The universe doesn't give a shit that some lumpy sacks of meat dislike certain experiences, and exactly the same action can be unpleasant for some people but pleasant for others. (BDSM enthusiasts, for example, often actively seek out experiences that other people would consider painful.)
That depends on the context. If it's acupuncture, for example, it can be quite good, even if the precise sensation is exactly the same as the otherwise unpleasant case of poking myself with a needle while sewing.
It doesn't matter if it's "distinguishable". It's objectively worse. A pin prick might not be noticeable but a million is the worst torture imaginable.
You're assuming that dust specks across different people can be added, and then asserting that as evidence that dust specks across different people can be added. The addition is ridiculous.
That some arbitrarily minimal amount of subjective pain can be presumed to be actually distinguishable from the general background unpleasantness of being human in the first place.
Edit: Rephrased to remove gibberish resulting from temporary brain/keyboard disconnect.