There is dukkha as the first truth of the noble ones, and there is dukkha vedana - an unpleasant feeling. Similarly, there is sukha as the opposite of dukkha - the ultimate happiness of liberation, and there is sukha vedana - a pleasant feeling.
For an ordinary person without the right view, with a wrong view, dukkha vedana is the dukkha and sukha vedana is the sukha.
So, yes, the Buddha never denied that there is no sukha vedana in the world and there is only dukkha vedana, but he never equated dukkha vedana with the dukkha and sukha vedana with the sukha of liberation.
So what is the understanding of dukkha and sukha of each of the opponents in the ‘refutation’? Are their understandings of these terms the same? Are both of them speaking from the position of the noble ones and not from the position of an ordinary person with a wrong view?
Suppose there was a person affected by leprosy, with sores and blisters on their limbs. Being devoured by worms, scratching with their nails at the opening of their wounds, they’d cauterize their body over a pit of glowing coals. Their friends and colleagues, relatives and kin would get a surgeon to treat them. The surgeon would make medicine for them, and by using that they’d be cured of leprosy. They’d be healthy, happy, autonomous, master of themselves, able to go where they wanted. Then they’d see another person affected by leprosy, with sores and blisters on their limbs, being devoured by worms, scratching with their nails at the opening of their wounds, cauterizing their body over a pit of glowing coals.
What do you think, Māgaṇḍiya? Would that person envy that other person affected by leprosy for their pit of glowing coals or for taking medicine?”
“No, worthy Gotama. Why is that? Because you need to take medicine only when there’s a disease. When there’s no disease, there’s no need for medicine.”
“In the same way, Māgaṇḍiya, when I was still a layperson I used to entertain myself with sights … sounds … smells … tastes … touches known by the body, which are likable, desirable, agreeable, pleasant, sensual, and arousing. Some time later—having truly understood the origin, ending, gratification, drawback, and escape of sensual pleasures, and having given up craving and dispelled passion for sensual pleasures—I live rid of thirst, my mind peaceful inside. I see other sentient beings who are not free from sensual pleasures being consumed by craving for sensual pleasures, burning with passion for sensual pleasures, indulging in sensual pleasures. I don’t envy them, nor do I hope to enjoy that. Why is that? Because there is a satisfaction that is apart from sensual pleasures and unskillful qualities, which even equals heavenly pleasure. Enjoying that satisfaction, I don’t envy what is inferior, nor do I hope to enjoy it.
Suppose there was a person affected by leprosy, with sores and blisters on their limbs. Being devoured by worms, scratching with their nails at the opening of their wounds, they’d cauterize their body over a pit of glowing coals. Their friends and colleagues, relatives and kin would get a surgeon to treat them. The surgeon would make medicine for them, and by using that they’d be cured of leprosy. They’d be healthy, happy, autonomous, master of themselves, able to go where they wanted. Two strong men would grab them by the arms and drag them towards the pit of glowing coals.
What do you think, Māgaṇḍiya? Wouldn’t that person writhe and struggle to and fro?”
“Yes, worthy Gotama. Why is that? Because that fire is really painful to touch, fiercely burning and scorching.”
“What do you think, Māgaṇḍiya? Is it only now that the fire is really painful to touch, fiercely burning and scorching, or was it painful previously as well?”
“That fire is painful now and it was also painful previously. That person was affected by leprosy, with sores and blisters on their limbs. Being devoured by worms, scratching with their nails at the opening of their wounds, their sense faculties were impaired. So even though the fire was actually painful to touch, they had a distorted perception that it was pleasant.”
“In the same way, sensual pleasures of the past, future, and present are painful to touch, fiercely burning and scorching. These sentient beings who are not free from sensual pleasures—being consumed by craving for sensual pleasures, burning with passion for sensual pleasures—have impaired sense faculties. So even though sensual pleasures are actually painful to touch, they have a distorted perception that they are pleasant.
Suppose there was a person affected by leprosy, with sores and blisters on their limbs. Being devoured by worms, scratching with their nails at the opening of their wounds, they’re cauterizing their body over a pit of glowing coals. The more they scratch their wounds and cauterize their body, the more their wounds become foul, stinking, and infected. But still, they derive a degree of pleasure and gratification from the itchiness of their wounds. In the same way, I see other sentient beings who are not free from sensual pleasures being consumed by craving for sensual pleasures, burning with passion for sensual pleasures, indulging in sensual pleasures. The more they indulge in sensual pleasures, the more their craving for sensual pleasures grows, and the more they burn with passion for sensual pleasures. But still, they derive a degree of pleasure and gratification from the five kinds of sensual stimulation.
What do you think, Māgaṇḍiya? Have you seen or heard of a king or a royal minister of the past, future, or present, amusing themselves supplied and provided with the five kinds of sensual stimulation, who—without giving up craving for sensual pleasures and dispelling passion for sensual pleasures—lives rid of thirst, their mind peaceful inside?”
“No, worthy Gotama.”
“Good, Māgaṇḍiya. Neither have I. On the contrary, all the ascetics or brahmins of the past, future, or present who live rid of thirst, their minds peaceful inside, do so after truly understanding the origin, ending, gratification, drawback, and escape of sensual pleasures, and after giving up craving and dispelling passion for sensual pleasures.”