First published in 1971, Professor Putnam's essay concerns itself with the ontological problem in the philosophy of logic and mathematics - that is, the issue of whether the abstract entities spoken of in logic and mathematics really exist. He also deals with the question of whether or not reference to these abstract entities is really indispensible in logic and whether it is necessary in physical science in general.
1. What Logic Is? 2. The Nominalism-Realism Issue 3. The Nominalism-Realism Issue and Logic 4. Logic vs Mathematics 5. The Inadequacy of Nominalistic Language 6. Predicative vs Impredicative Conceptions of "Set" 7. How Much Set Theory is Really Indispensible for Science? 8. Indispensibility Arguments 9. Unconsidered Complications