Moving from some reflections on the empirical practice of measurement and on the nature of visual perception, we present a constructivist approach to objects. At the basis of such approach there is the idea that all we may know about what is out there is always mediated by some sort of apparatus, being it a measurement instrument or our perceptual system. Given this perspective, some questions are in order: how are objects identified and re-identified through time from the outcomes of apparatuses? How can we distinguish different (kinds of) objects? Our first goal will be to make explicit the mechanism used to build objects from the apparatuses' outcomes, emphasizing what are the ontological and representational problems this construction faces. A second contribution will be a preliminary discussion of some possible ways to distinguish social objects, the constructed objects par excellence, from physical ones. A third contribution will be an attempt to make a bridge between two scientific communities that rarely seek contact or mutual recognition: that of formal ontologies and that of formal concept analysis.