Daivd Hume's An enquiry of human understanding

Hume classifies human reason into two categories: relations of ideas and matters of fact. According to Hume relations of ideas can be demonstratively proven or certain. He gives the example of such as in math it can be proven that the square of the hypotenuse is equal to the squares of the two sides. Matters of fact are not ascertained in the same manner. Matters of facts are ideas which are caused by impressions or …

…though the cause was proceeded by an effect there is no evidence that the cause was responsible for the effect. It is our experience that is underlying this assumption that a cause produces an effect. If we had no experience we would no way to tell what would come after the cause, anything could be possible. We can only make guesses on what will happen in the future, based on our experiences of the past.