Chemical Selectivity

Chemical selectivity could be, or at least was proposed by nassau to be a possible well, nowadays we speak of bio signatures. But the fact o the matter is, that doesn't define life, does it? It just says, we're looking for something tha we think is a characteristic of the kind of life that we're familiar with. How many other kinds of life might there be out there? And and that's something we just don't know. We don't have enough information to build attaxonome to say, these things are alive and these things are dead."