Some writers have suggested that it would be desirable to assess the state of the Earth''senvironments by making use of a concept of ecosystem health. We subject this suggestion toscrutiny first by calling attention to obscurities inthe notion of an ecosystem and then by callingattention to obscurities in and objections to someviews about ecosystem health. Finally, we note, thateven if ecosystem health can be adequately clarified, there are reasons for saying that whetherwe are morally obligated to protect the health ofsome (...) ecosystem depends on other circumstances. In many possible circumstances we would not beobligated to protect the health of a particularecosystem. (shrink)