In this thesis I have explored some of the ways in which the contexts of epistemology, ethics and designing architecture are each concerned with undecidable questions (that is, with those questions that have no right answers). Drawing on design research, second‐order cybernetics and radical constructivism, I have understood this undecidability to follow in each case from our being part of the situation in which we are acting. This idea is primarily epistemological (being part of the world we observe, we cannot verify the relationship between our understanding and the world beyond our experience as it is impossible to observe the latter) but can also be interpreted spatially and ethically. From this starting point I have developed connections between questions in architecture, epistemology and ethics in two parallel investigations. In the first, I have proposed a connection between design and ethics where design is understood as an activity in which ethical questioning is implicit. Rather than the usual application of ethical theory to practice, I have instead proposed that design can inform ethical thinking, both in the context of designing architecture and also more generally, through (1) the ways designers approach what Rittel (1972) called “wicked problems” (which, I argue, have the same structure as ethical dilemmas) and (2) the implicit consideration of others in design’s core methodology. In parallel to this I have explored the spatial sense of the idea that we are part of the world through a series of design investigations comprising projects set in everyday situations and other speculative drawings. Through these I have proposed reformulating the architectural theme of place, which is usually associated with phenomenology, in constructivist terms as the spatiality of observing our own observing and so as where the self‐reference of epistemology (that we cannot experience the world beyond our experience) becomes manifest.