1. A method of measuring similarity between instances in an ontology for use in an information retrieval system, the method comprising the steps of: obtaining a set of instances from the ontology; computing a first similarity metric that measures similarity between instances in the set of instances with respect to ontology concepts to which the instances belong; and storing at least one taxonomy induced by the first similarity metric, wherein the at least one induced taxonomy is usable for responding to requests submitted to the information retrieval system; wherein the first similarity metric measures similarity of instances i and j in the set of instances based on the similarity of C(i) and C(j), where the C(i) and the C(j) represent sets of concepts to which the instances belong; and wherein the first similarity metric considers concept membership statements of the instances in the set of instances by defining a description of an individual and a commonality between the instances based on the ontology concepts to which the instances belong; and further wherein the obtaining, computing and storing steps are performed by a processor and memory.