I. Introduction
Binary questions are frequently asked for the confirmation of given information. These questions can be answered by yes/no answers. Similarly, binary causal questions (BCQs) are asked to confirm whether or not a causal relationship exists between two candidate concepts. Fig. 1 depicts an example BCQ. In the example question, “Could COVID-19 cause lung failure?,” COVID-19 and lung failure are two candidate concepts, and the question asks whether or not there is a causal relationship between them.