Moral judgments are known to change in response to changes in external conditions. But how variable are moral judgments over time in the absence of environmental variation? The moral domain has been described in terms of five moral foundations, categories that appear to capture moral judgment across cultures. We examined the temporal consistency of repeated responses to the moral foundations questionnaire over short time periods, fitted a set of mixed effects models to the data and compared them. We found correlations between changes in participant responses for different foundations over time, suggesting a structure with at least two underlying stochastic processes: one for moral judgments involving harm and fairness, and another for moral judgments related to loyalty, authority, and purity.