We introduce the concept of 'pluralistic licensing', which we describe as the award of licenses under the assumption that opportunistic secondary spectrum access will be allowed, and that interference may be caused to the primary with parameters and rules that are known to the primary at the point of obtaining the license. A key aspect of the concept is that the primary will choose from a range of offered 'pluralistic licenses' each with associated fees, and each specifying alternative opportunistic access rules and associated interference characteristics. Our proposal is a novel means to take forward spectrum licensing which is fair to both primary and secondary users and takes into account the requirements of both parties. The objective is to incentivize the primary to obtain this type of license through means such as a reduced license fee, whereby the opportunistic secondary spectrum access will use 'cognitive radio' mechanisms to avoid causing interference to the primary or to otherwise keep interference within known parameters.