Creating a unified model of life in the universe – history, extent and future – requires both scientific and humanities research. One way that humanities can contribute is by investigating the relationship between philosophical commitments and data. Making those commitments transparent allows scientists to use the data more fully. Insights in four areas – history, ethics, religion and probability – demonstrate the value of careful, astrobiology-specific humanities research for improving how we talk and think about astrobiology as a whole. First, astrobiology has a long and influential history. Second, astrobiology does not decentre humanity, either physically or ethically. Third, astrobiology is broadly compatible with major world religions. Finally, claims about the probability of life arising or existing elsewhere rest heavily on philosophical priors. In all four cases, identifying philosophical commitments clarifies the ways in which data can tell us about life.