Causal thinking and writing

Every time I teach a class or get to read and edit others writing I add to my mental list of tips and recommendations for good writing. This semester I'm focused on causal thinking and writing. In other words, encouraging students to support their claims of relationships between variables. I tell them that their best support comes from citing research that finds the relationship. If that's not available, you need to spell out your hypothesized mechanism REALLY clearly, and cite closely relevant research. I still find that students like write "but what if" proposals. By that I mean they suggest a possible relationship between two variables, but leave it at that. They don't make the mechanism clear. I need to work on ways and examples to motivate this.