This book explores Wittgenstein’s unsettling remark in the Tractatus that the only necessity that exists is logical necessity. It suggests that the notion of necessity is a primitive notion, and, as such, both a requirement for human cognition and constitutive of rational thought. On this basis, the book then reexamines some of the perennial questions of philosophy including logic itself, beauty, law, truth and the concept of God. All of these topics are seen to be closely related to the notion of necessity. It is argued that if logical necessity is the only necessity that exists, then Kant’s notion of the subjective necessity of aesthetic judgments must be reconsidered. Likewise, metaphysical, moral, and practical necessity must all be revised. Finally, a new dimension is added to the analysis. It is shown that the notion of logical necessity is human in its origin, and yet also absolute. This insight reopens the possibility of logical absolutism, as opposed to the current, general consensus around logical relativism. Moreover, it becomes possible to entertain a notion of logical absolutism without the problematic baggage of metaphysical and/or divine considerations. This new sense of logical absolutism facilitates a reconsideration of certain epistemological claims directly related to logical truths, for example, so-called analytical propositions. Logical Necessity and Rational Thought is essential reading for all scholars, researchers and advanced students of philosophical logic. It is also ideal for researchers of the thought of Ludwig Wittgenstein.