 The theories discussed in this section encounter a number of important problems in accounting for function phenomena in the artifact realm. One such problematic phenomenon is the distinction between proper and non-proper functions. This does occur in the biological realm—pigeon beaks did not evolve to peck buttons for a food reward, for example—but it is relatively rare. In material culture, it is ubiquitous. Humans are just very good at adopting whatever artifact will accomplish their purposes, regardless of its proper function. Stop a random person in the street and ask—she will have a story. Intentionalist approaches have more difficulty making this distinction, because for these views human intentions are the only mechanism for establishing functions, and this elides the distinction unless some difference can be discerned in the intentions themselves. Authors who have discussed this issue recently include Wybo Houkes and Pieter Vermaas (2010), Beth Preston (2013) and Simon Evnine (2016). Another problem is accounting for malfunction. Just as any theory of representation must account for misrepresentation, any theory of function must say something about cases of failure to perform, and whether or not that failure is a malfunction or something else. Addressing this issue depends to some extent on the distinction between proper and non-proper functions, because malfunction only seems an appropriate designation in the case of failure to perform a proper function—failure to do what the artifact is supposed to do, in other words. This issue is especially important for the philosophy of technology and engineering side of the artifact debates, where understanding the epistemology of problem solving and innovation depends in part on understanding failure to function and how to learn from and deal with it. Authors who have covered this issue include Neander (1995), Baker (2007), Franssen (2006; 2009), Houkes and Vermaas (2010) and Kroes (2012).