The article focuses on the ontological foundations of lifeworld as Being taken for granted and viewed as a communication phenomenon par excellence, conceptualized as signifying in the presence of others. It is argued that, because there is always a wider horizon of experience against which anything can appear, lifeworld as something continuous can only be thematized in discrete scientific forms. In the article, lifeworld is discussed through the perspectives of four different sciences. From the natural science perspective, lifeworld is conceptualized as an arrangement contingent on the interconnections of human and nonhuman beings. It takes the form of conversation and can be best examined by Conversation Analysis. From the social science perspective, lifeworld is conceptualized as an order that is constituted by symbolic interactions and guided by relevant types and rules that structure our experience. It takes the form of intersubjective action as a meaningful back and forth and can be best examined by Discourse Analysis. From the cultural sciences perspective, lifeworld is the realm of spirit passed from generation to generation that gives human culture its meaning. It takes the form of significant expressions and can be best examined by Textual Hermeneutic Analysis. And, from the philosophical perspective, lifeworld is constituted by phenomena that appear, or monstrate themselves, to consciousness. This lifeworld is of absolute reversibility and immediacy and can be best examined by Critical Analysis, i.e., by postulating our relation to any object through contemplation. Thus, as Being, lifeworld is said in many ways, each lifeworld being relevant in its own way by providing a valuable resource - physico-biological, normative, significational, and transcendental.
