Explore the intersection of contractualism and software engineering in this thought-provoking 28-minute conference talk from RubyConf 2021. Delve into the ethical decision-making process for engineers, from minor design choices to major algorithmic impacts. Learn about the concept of the "user stack" and how to consider all individuals influenced by your work. Gain insights on applying contractualist principles to make ethical choices in software development and effectively communicate these decisions within your organization. Discover how treating users as part of a larger community can lead to more responsible and impactful engineering practices.