Abstract
In order to explore thinking in technological innovation by using modal logic, a technology is analyzed to be a set of action propositions and a technological innovation is regarded to form a new set of such propositions by deliberating each action proposition and then introducing new ones. An action proposition is indispensable if regarded as necessary no matter how the technology involved is innovated. An action proposition is feasible if workable but replaceable in terms of achieving some effect(s). Hence, a technological innovation constitutes a balance between indispensability and feasibility. Logics containing the operators of indispensability and feasibility can be used to draw inferences regarding technological innovation. Broadly speaking, logical systems provided in this paper are design logic.