Can the theory of conceptual spaces developed by Peter Grdenfors (2000, 2014) and others be applied to moral issues? Martin Peterson (2017) argues that several moral principles can be construed as regions in a shared similarity space, but Kristin Shrader-Frechette (2017) and Gert-Jan Lokhorst (2018) question Petersons claim. They argue that the moral similarity judgments used to construct the space are underspecified and subjective. In this paper, we present new data indicating that moral principles can indeed be construed as regions in a multidimensional conceptual space on the basis of moral similarity judgments. Four hundred and seventy-five students taking a course in engineering ethics completed a survey in which they were presented with ten cases (moral choice situations) featuring ethical issues related to technology and engineering. Participants were asked to judge the moral similarity of each pair of cases (45 comparisons) and to select which moral principle (from a list of five alternatives plus a sixth option:
none of the principle listed here) they believed should be applied for resolving the case. We used interval multidimensional scaling (MDS) as well as individual differences scaling (INDSCAL) for analyzing the moral similarity judgments. Despite noteworthy individual variations in the judgments, the five moral principles included in the study were discernable in the aggregate multidimensional spaces, even for participants with no previous exposure to the principles. Participants tended to apply the same moral principles to cases rated as morally similar. Our overall conclusion is that moral similarity judgments, and their representation in multidimensional spaces, can help us identify moral principles that are relevant for assessing difficult moral choice situations.