 The account of “levels of mechanisms” introduced by Bill Bechtel (2008) and Carl Craver (2007) has recently become the standard view of levels in philosophy of neuroscience. The context of this account is the paradigm of “new mechanism” that currently dominates philosophy of neuroscience and large parts of philosophy of science more generally (see the entry  mechanisms in science).  In levels of mechanisms, there are mechanisms at higher levels and their components at lower levels. The mechanistic account proposes a contextualized conception (as opposed to the comprehensive conception of the layer-cake) that articulates levels in terms of constitutive parthood within a mechanism (Craver 2007: 188–189; Kaplan 2015: 20; see also Cummins 1975 for an early expression of this idea). This approach offers several advantages over the layer-cake account: For one thing, it abandons the goal of providing a global or comprehensive understanding of levels that applies homogeneously to all systems in nature. Instead, the aim is to construe levels in a scientifically informed manner whereby level demarcations only make sense on case-based grounds (see also Love 2012 for a local approach to levels that is not explicitly tied to the notion of a mechanism). The mechanistic account also completely eschews any tidy correspondence between the structure of the natural world and the structure of the natural sciences: Levels of mechanisms are levels in nature, and there is no straightforward mapping from these levels to theories or fields of science (Craver 2007: 176). Finally, the mechanistic account of levels supports a positive account of pluralistic, multilevel explanation that emerges as a powerful alternative to accounts of reductionism in biology (Craver 2005; cf. Brigandt 2010: 297).