I went with Caroline down to the Rock Beach, a small stretch of sand, garbage, driftwood and stones along Lake Erie near our house. We go to hunt for pretty rocks and "sea glass" (really fragments of old bottles that have been worn smooth by the water.)
Ok, back to work. The idea of nonattachment developed during the axial age of Indian philosophy, from around 800 BCE to the beginning of the common era, an age which saw the writings of the Upanishads and the Bhagavad Gita and the lives of the Buddha and Mahavira. It cannot be traced to particular thinkers interested in promoting particular ideas, the way disinterestedness can, and it was not intended as an account of a single aspect of experience, such as beauty. Instead it was an integral aspect of a program for attaining complete spiritual liberation.
Despite the radically different origins of the two ideas, I maintain that they describe similar mental states. In each case, we are looking at a suspension of means-ends rationality and some form of putting desire on "hold." Admittedly, mental states are a bitch to individuate, and clearly depend on factors that are not "in the head," including social and physical reality (cite annoying twin earth-type research here.) You cannot know what a subject is thinking about simply by looking at the the state of his brain, because the same brain state might mean something different in different social and physical contexts. This means that on one level, the mind of a Hindu Sadhu in deep meditation is obviously going to be in a very different category than the mind of a 18th century contemplating a lovely view of the countryside. Still, we can productively classify mental states based mostly on features that are "in the head", including phenomenological descriptions of the state and, as technology advances, descriptions of physical brain states, using only very general descriptions of external social and physical reality. For instance, we can say that two individuals in very different circumstances are both "fearful," based on their descriptions on how they feel and increased blood flow to, say, the amygdala,1 even though one person is afraid of karmic pollution from touching a dalit and the other a humiliating loss of face in the House of Lords. Similarly, I think that if you focus on the aspects of disinterestedness and nonattachment that are mostly "in the head", you will see a strong resemblance. More importantly, insights into the mental state as it has been described in one tradition can help us understand related states in a different tradition.
1 Whenever I read about the neurological correlates to any interesting mental process, it always seems to involve some combination of the amygdala, the hypothalamus, and the prefrontal cortex. I'm beginning to think that the brain really only has these three parts and that "increased activity in the amydala, hypothalamus, and prefrontal cortex" actually means the same thing as "brain activity." People only substitute "amygdala" for "brain" because it sounds fancy. I used to hear about the hippocampus sometimes, but I think the hypothalamus is the new hippocampus of fake brain science.