The concept of disease--vague, complex, or just indefinable?

The long ongoing and partly heated debate on the concept of disease has not led to any consensus on the status of this apparently essential concept for modern health care. The arguments range from claims that the disease concept is vague, slippery, elusive, or complex, and to statements that the concept is indefinable and unnecessary. The unsettled status of the concept of disease is challenging not only to health care where diagnosing, treating, and curing disease are core aims, but also to the branch of philosophy that tries to clarify concepts. This article discusses three claims about the concept of disease: that it is vague, complex, and that it is indefinable. It investigates (a) what is meant by these claims (b) what their implications are, and (c) whether the claims are sound or not. It is argued that some of the arguments are flawed and miss important points about concept analysis. This does not mean, however, that disease is a clear concept with a crisp definition. It only rules out speculative claims that disease necessarily is vague, complex, and indefinable. It appears at least as hard to show that disease is indefinable as it is to define it.