I know right. If polio causes paralysis then why do only 0.5% of people who contract polio become paralyzed? Checkmate. That is mixing up necessary versus suff

I know right. If polio causes paralysis then why do only 0.5% of people who contract polio become paralyzed? Checkmate. That is mixing up necessary versus sufficient. If all people who develop Alzheimer’s contracted HSV-1 prior to developing Alzheimer’s and all people who did not contract HSV-1 do not develop Alzheimer’s (technically implied by my first statement), then you can make a good case for causality. Obviously you can do better, but that is a good start.