The book, Professional Ethics: A Guide to Responsible Decision Making, by Sotonye Big-Alabo (Ph.D), is an invitation to engage with the essential philosophical query posed by Socrates: "how ought we to live?". The text progresses from foundational concepts, such as the dominance of moral values, to systematic frameworks known as Moral Theories, which illuminate right and wrong based on outcomes (Consequentialism) or duties (Nonconsequentialism). The core focus is on applied ethics, translating principles like the Principle of Human Dignity and the pre-eminence of Reason into actionable guidance across key professional domains. The book dedicates full chapters to Business Ethics, Medical Ethics, Media Ethics, and Engineering Ethics. Within these fields, it explores how professionals must balance competing responsibilities, such as a manager's duties to stakeholders, a physician's navigation of autonomy versus beneficence, and a media professional's pursuit of truth. The ultimate goal is to help readers develop the coherent, well-reasoned perspectives necessary for navigating moral complexity and fostering productive discourse.