Hi, I don't think you would necessarily need to think about this in terms of course and effect, at least not consciously, but I do think that the most efficient and effective route to solving this would likely involve thinking about ways the conclusion could be wrong even if the premises hold.
How, then, could junk science still be harmful even if it will be corrected when replicated?
My immediate reaction is that maybe when a bad study is published, it will be covered heavily by media, and the junk science will become conventional wisdom before any replication is even attempted. In this case, it would do harm before other scientists have a chance to replicate and debunk it.
A does not fit this exactly, but it makes this scenario more likely. If there is a long time frame for this to happen, it makes it more likely to happen.
More generally, I would usually ask myself how the conclusion could be wrong even if the premises are right, and use that to think of ways to attack the argument.
