The leisure to do the thinking whose results are gathered here has largely been provided by the Academy of Finland, whose support has also made possible the help and co-operation of a group of younger logicians and philosophers. Less tangible support and help is unfortunately harder to record and to thank for. Once again, in working on the many themes I have tried to weave together in this book I have incurred more intellectual and moral debts I can in so many words acknowledge here. Let me only say that the closer to home I get the greater they become. I have especially in mind my colleagues and students at Stanford; my colleagues in Helsinki; the past and present members of my research group in Helsinki; and incom parably more than anybody else my wife Soili. Helsinki, April 1975 JAAKKO HINTIKKA INTRODUCTION A literal-minded reader might easily object to the (sub)title of this volume. What is to be found here, he might allege, are neither models, nor modalities stricto sensu, nor yet any completely new applications of modal logic. Even though the purpose of the title is only to signal the con tinuity between the present volume and its predecessor, Models for Modalities (D. Reidel Publishing Co., Dordrecht, 1969), the objection is sufficiently well taken to serve as an excuse for an attempt to put my enterprise in a wider perspective.