Reasoning is a crucial part of natural language argumentation. To comprehend an argument, one must analyze its warrant, which explains why its claim follows from its premises. As arguments are highly contextualized, warrants are usually presupposed and left implicit. Thus, the comprehension does not only require language understanding and logic skills, but also depends on common sense. We provide a freely licensed dataset with warrants for 2k authentic arguments from news comments. The following annotations were carried out: stance of the argument, reason spans, added warrants explaining reasoning from premises to the claim.