What If. . . Collected Thought Experiments in Philosophy is a brief, inexpensive collection of over 100 classic and contemporary “thought experiments”, each with an accompanying commentary, that explore philosophical arguments and often address a genuine problem in life. The value of the book is in its simplicity in both format and tone: Each thought experiment is accompanied by commentary that explains importance of the experiment, and questions to provoke thought and discussion, all encapsulated within two pages. The book is direct, clear and conversational but does not dilute difficult ideas.