In the realm of logic, the concepts of tautology, proposition, and contradiction play distinct roles in defining truth. A tautology is an assertion that is undeniably true in all circumstances, providing certainty. In contrast, a proposition holds a level of possibility, where its truth can vary depending on specific conditions. This positions propositions in a middle ground, unlike tautologies that guarantee truth.

Additionally, contradictions represent statements that cannot be true under any scenario, establishing them as impossible. Wittgenstein's exploration of these concepts in his work imparts a clear distinction among them, highlighting how they relate to our understanding of truth and logical discourse.