Why causation cannot be determined if a relationship has bee

Why causation cannot be determined if a relationship has been identified? What happens when you add a cause and effect relationship?

Solution

Not in all cases that if a relationship exists, there is causation. Let us give an example.

All people that gets cancer drink water. Thus, there will be a relatinship between drinking water and cancer. However, you cannot say that cancer is caused by drinking water.

When you add a cause and effect relationship, we ignore other factors that may affect the dependent variable. Usually, there are many other variables affecting the dependent variable, so we are most probably making a mistake when establishing causation.