I’ll present OmegaC, a probabilistic programming language with counterfactuals originally presented at ICML 2021, from a semanticist’s point of view. Counterfactuals are a new effect that makes it easy to express queries like “how much larger would the output be had the input been 1 larger.” I’ll show that counterfactual execution can actually be viewed as a combination of two features previously thought useless, laziness and dynamic scope, and I’ll present the (surprisingly simple) proof that dynamic scope, and therefore also the counterfactual do operator, is not “syntactic sugar” for other operators (i.e.: not macro-expressible).