Is it grammatical to introduce a result clause using “then”?

Question

Is it grammatical to introduce a result clause by using *then* as in these examples: * Don’t be lazy – *then* you will fail. * Don’t kill him – *then* you will regret it. If so, then is the *then* in these examples a conjunction? I’ve not found any resources that mention this – they usually say that result clauses are usually introduced by conjunctions such as *so* or *so that* which in the above examples would read: * Don’t be lazy *so that* you *then* fail. * Don’t kill him *so* you regret it.

Answer 1

Instead of then, use or else, e.g., Don't be lazy, or else you will fail.. Don't kill him, or else you will regret it.

Answer 2

Think about the logic here. "Don't be lazy then you will fail." means if you're NOT lazy you will fail, but you mean the opposite. "If you are lazy, you will fail." So, it should be "If you kill him, you will regret it." Because "Don't kill him then you will regret it" means you will regret it if you DON'T kill him.

Your examples using "so" and "so that" are grammatically incorrect. It should be "Don't kill him OR you will regret it."