 Some philosophers have proposed that there are different explanatory purposes for contents to serve, and one kind of content cannot serve all of them. (On the general strategy of dividing contents in this way see Fodor 1987 and White 1991.) Such philosophers think experiences have multiple contents. One example of such a position holds that experiences have contents that are both conceptual and non-conceptual (for more on this distinction, see  Section 6.2  below. This kind of duality is explored by Reiland and Lyons 2015, and defended by by Lyons 2005a, 2005b and Bengson, Grube and Korman 2011). Another holds that experiences have both ‘gappy’ contents (somewhat akin to open sentences), but have object-involving contents as well when the experience stands in the right causal relations to environment (e.g., Burge 1991 and Schellenberg 2010; for discussion, see Martin 2003). Here the idea is that the gappy content reflects the phenomenology of the experience and the commonality in content between indistinguishable hallucinations and non-hallucinations, whereas the object-involving contents reflect intuitions about accuracy conditions for experiences that are adequately connected to the environment. A related idea is that contents of experience include both general and object-involving contents (Siegel 2010b).