The proposed release of genetically modified mosquitoes (GMM) in the Florida Keys to combat the spread of diseases such as Zika prompted heated local debate, turning a seemingly routine mosquito control policy into a public scientific controversy. Arguments about the GMM derive from inventional commonplaces where the historical conflict between democratic systems of civic deliberation and the epistemic authority of expertise is instantiated. This project analyzes the topoi that Keys participants gather around to generate their argumentative positions as published in public, local print and digital news articles, blog posts, and letters to the editor between 2011 and 2016. Investigating the commonplaces that orient the argumentative trajectories of Keys participants reveals that each relational topos intersects with individual worldviews, risk assessments, and standards and can therefore be used for contradictory arguments. The many complex and connected factors that influence participant positions must be appreciated and acknowledged in any such civic deliberation about a science-related policy or technology. There is no easy resolution for such conflicts, such as clarifying scientific data for the public, to generate consensus; the irresolvable tension between democracy and expertise underlies public scientific controversies and requires mutual respect and appreciation for the varied reasons why people disagree to move towards more productive civic discourse.