 These and other accounts hold that artifacts ontologically depend on historical facts, often historical intentions of the creator. Others argue that the emphasis on historical processes is misguided, and that what matters is how an object is used in the present (Keil, Greif et al. 2007; Preston 2009, 2013). Not everyone agrees that artifacts must have a function (or an intended function). Objects such as doodles and rock stacks are created without either functions or functional intentions. Even if artifacts necessarily involve functions, the role of functions in distinguishing artifactual kinds from one another might be debated. It may be that artifactual kinds are individuated by function, but many artifactual kinds (such as houses) seem to have multiple functions, and some sets of distinct artifactual kinds (such as bicycles and tricycles) may all have the same function.