Organisms construct their ecological niches when they define, create and alter their surrounds by their metabolism, behavior, and choices. Richard Lewontin (1983, 1985, 2000, 2001) argues from these phenomena that the metaphor of construction should replace the metaphor of adaptation in evolutionary theory. The metaphor of adaptation is the idea that evolution by natural selection is a process of adaptation. In this dissertation, I argue that the subsequent literature on "niche construction" and their models are merely revisions and extensions of the adaptationist explanatory schema. They fail to recognize how Lewontin's constructivist views undermine adaptationism as an explanatory framework and revolutionize interpretations of "fitness", "niche", and "natural selection." The key difference between Lewontin and the maintstream view is how they interpret the adaptationist assumption that the internal mechanisms of variation are independent from the external, environmentally driven process of natural selection, with "one generating ‘problems’ at random with respect to the organism, the other generating ‘solutions’ at random with respect to the environment." (Lewontin, 2001, p. 47) John Odling-Smee, Kevin Laland, Michael O'Brien, Peter Godfrey-Smith, and others merely focus on how organism-induced environmental changes affect evolutionary dynamics. However, this is consistent with the problem-solution metaphor if the niche constructing organisms merely create the problems they later solve. I argue that niche construction undermines adaptationism because it implies that there is no "problem" in the environment. When each individual creates its own niche, the environment of the population consists of a myriad of individual selective environments dependent on organismic variation and no longer constitutes a single problem for the population to solve. After analyzing how the explanatory roles of these concepts are challenged by niche construction, I develop a theoretical model based on Lewontin's original view and apply it to different disciplines.