  Those writing about Hobbes often describe Zabarella’s method as having two parts, resolution and composition. Resolution moves from the thing to be explained, which is an effect, to its causes, and then composition brings you back from causes to effects. At a suitably general level that is correct, but it misses much detail. Most importantly, Zabarella’s method — as seen for instance in his work De Regressu – is better described as having three parts. A crucial though somewhat mysterious third step stands between the move from effect to cause and that from effect to cause. The complete sequence, the arguments from effect to cause and back again, Zabarella calls regressus. This sequence improves our knowledge, taking us from confused to clear knowledge of something. But how do we do this? The first step is to move from having confused knowledge of the effect to having confused knowledge of the cause. Roughly, you need to figure out what caused the thing you’re trying to explain. The second step moves from confused to clear knowledge of the cause. This step works, Zabarella thinks, by a sort of intellectual examination of the cause. The aim is not just to know what thing is the cause, but to understand that thing. The final step then moves from the clear knowledge of the cause to clear knowledge of the effect. That is, your new full understanding of the cause gives you better understanding of the thing caused by it.