First, separate what was said from what would need to be true.
Ask: “Assuming all these premises are true, does the conclusion necessarily follow?”
Do not argue with the conclusion until you know what unstated premise is doing the work.
Add the missing premise explicitly if needed.
Once you spot the gap, write the missing bridge as a separate line and mark it as implicit.
That turns vague disagreement into something concrete. Now you can ask:
- Is this hidden premise true?
- Is it too broad?
- Is it the wrong definition?
- Is the causal claim unsupported?
- Is the moral rule shared?
Not all premises play the same role.
- Independent: supports the conclusion on its own
- Linked: only works together with another premise
- Serial: supports another premise, not the conclusion directly
This matters because it tells you where to attack or strengthen the argument.
If two premises are linked, knocking out one collapses the whole support. If a premise is serial, it may be supporting a subclaim rather than the conclusion.
Use three checks:
- Removal test: Take one premise out. Can the conclusion still be reached? If yes, it may be redundant or misplaced.
- Counterexample test: Ask: “Can I imagine a case where all the premises are true but the conclusion is false?” If yes, something is still missing.
- Necessity/sufficiency test: Are the premises together enough? Is each one actually needed?
This is the practical heart of the method. It tells you whether the argument is actually complete.
State the conclusion, list the reasons, ask whether they force the conclusion, make the missing bridge explicit, then test whether the full set really holds.