Digital discussion spaces have changed the shape of discursive argumentation considerably. While there is not much explicit reasoning on Twitter, many users link to external resources in their tweets. This study zooms in on the justificatory capacity of those links and investigates their deliberative function on the platform. A qualitative exploration of material from four countries shows that links to external resources support Twitter discourse by regularly substantiating user statements in the context of both information and argumentation. Links with a truth-based informative function are posted to support deliberative truth claims with empirical evidence, thus adding primarily to theoretical discourses. Links with a norm-based argumentative function are shared to legitimate positions against social standards. They contribute to practical discourses about courses of action by sustaining deliberative claims for normative rightness. The country comparison suggests that societal divisions foster a norm-based argumentative rather than truth-based informative use of links on Twitter.
