Gizbert-Studnicki considers how we are to understand the social thesis and whether the social thesis, properly understood, can handle Hume’s guillotine, that is, the problem also known as the fact-value gap or the is-ought problem that Hume first articulated in book III, part I, section I of his A Treatise of Human Nature (1739), according to which one may not logically derive an ‘ought’ from an ‘is’. Having distinguished three interpretations of the social thesis – the social sources thesis, the sources thesis and the social fact thesis – he focuses on the social fact thesis, which is a metaphysical thesis according to which legal facts are ultimately determined by social facts alone. Gizbert-Studnicki then considers three different ways of understanding the relation between social facts and legal facts along the lines of the social fact thesis, namely, reduction, supervenience and grounding. He maintains that while all three relations are more or less problematic, the grounding relation is to be preferred, and that adopting the idea of grounding helps us avoid Hume’s guillotine, since grounding is not a matter of entailment but a metaphysical relation that holds between facts.