There are more ways to weaken the conclusion - here are some of the thoughts

1. Find the alternate cause / alternate path to the conclusion

2. Find the way to reverse the cause and effect - this is also called reverse causal hypothesis

3. Find a way to demonstrate that the effect exists before the cause

4. Find a way to exemplify that the conclusion is extreme and is based on leap of faith

5. Find a reason to demonstrate that the sample used in the study is not representative of the population. Hence the conclusion is based on unrepresentative data.

6. Find a reason that the conclusion is confusing correlation with cause and effect. Hence the conclusion should be inferring just correlation not causation.

7. Find a reason that conclusion is confusing the necessary condition with the sufficient condition. Say that "necessary" premise is not sufficient to bring about the effect and hence the conclusion is unwarranted

8. Find a reason to state that the conclusion is based on the "old" trend and old customs of doing the things. Hence the conclusion is obsolete / no more valid.