C. West Churchman’s five inquiring systems are considered in the light of Polanyi’s distinction between tacit knowing and practical thinking. It is suggested that the five inquiring systems, as distinct and crucial elements of the learning organization, can be divided into two perspectives: the modes of tacit knowing and the levels of practical thinking. While practical thinking is of great importance to the day-to-day management and the analysis of past events of an organization, tacit knowing critically contributes to the sustainable growth and future direction of an organization through its connection with (1) intuition, (2) holism, and (3) ethics. As an example of tacit knowing, particularly in terms of ethics and intuition, a sixth inquiring system is proposed, namely, a Heideggerian inquiring system (HIS). What characterizes a HIS is, together with traditional methods of analysis of what is known, an organizational culture directed to the aim of discovering what is unknown in terms of products, markets, and competitive strategies and, most particularly, the capacities of organizational members. An existing real-world organizational example of an HIS is provided, examined, and discussed.