If you believe the past matters then it means you believe, that the past actually determines the present, and the causes control the effects. If we focus only on past causes and try to explain things solely through cause and effect we end up with determinism, because what this says is our present and our future have already been decided by past occurrences.

The past doesn’t matter, this is the standpoint of Adlerian psychology. In Adlerian psychology we do not think about past causes but rather about present goals.
This is the difference between etiology, the study of causation, and teleology, the study of the purpose of any given phenomenon, rather than its cause. As long as with stay in etiology thinking, we wont take a single step forward.

What I learned this week from reading The Courage to be Disliked