 The relation between sinful acts and sinful dispositions is complex. Having a sinful disposition can certainly make it easier to commit a particular kind of sin (e.g., being gluttonous makes it easier for me to drink another coffee beyond what I should), but a sinful disposition is neither necessary nor sufficient for committing a sinful act. It can’t be necessary, given that the primal sin isn’t explained by the presence of a sinful disposition. And it can’t be sufficient, since we don’t do all the sinful actions that a vice disposes us towards.