De Morgan's Law states that the disjunction of two propositions can be expressed as the negation of the conjunction of their negations. Given the equations τ(¬p)=1-τ(p) and τ(p∧q)=τ(p)∙τ(q), it can be shown that τ(p∨q) equals τ(p)+τ(q)-τ(p)∙τ(q). This relationship highlights the connection between probability logic and logical operations. The discussion emphasizes the importance of understanding these foundational principles in probability theory. Overall, De Morgan's Law provides a crucial framework for analyzing probabilities in logical expressions.