The general notion of species is one of the most fundamental in biology. But the idea of species is also one of the most persistent unresolved obsessions of biologists and philosophers. This new book investigates the multifaceted species problem as a "conceptual envelope" of that notion. Contemporary conceptualism and evolutionary epistemology allow for a fresh look by analyzing the framework of history viewed as changes of this problem ordered by changing philosophical-scientific contexts. In this analysis, the species problem is characterized in a nontrivial pluralistic manner, in contrast to an "accepted" monistic attitude. Key Features Provides new insights into the persistent species "problem". Focuses on the conceptual history and identifies pivotal landmarks in the history of the concept of species. Argues for a scientific consistency of species pluralism. Discusses the "evolving specieshood" in the context of new essentialism.