Excerpt: To be vibrant is to be “pulsating with life, vigor, or activity” (Mish 2003). Science education, like science, is a vibrant discipline. It pulsates due to competition among individuals and groups holding disparate views, as portrayed above (Hull 1988). One source of pulsation is the question: Can we justify that anything we know represents some aspect of reality? My purpose herein is to review an on-going dialectical discussion between communities of scholars that hold different views about whether or not knowledge represents reality, the nature of knowledge, and the process of coming to know. The adversaries, realism and constructivism, constitute different paradigms (Kuhn 1970) or models for characterizing knowledge and the || process of coming to know, for conducting research, and for recommending best practices in teaching and learning science. To achieve my purpose, I will take five steps: (1) define and describe knowledge; (2) describe realism, constructivism, and truth; (3) cite points of divergence, convergence, and peaceful coexistence; (4) review the key issue over which realism and constructivism collide from a constructivist perspective; and (5) offer a closing thought.