deserve to be punished or not? This is the fundamental issue underlying this question.

There are three views on this fundamental issue, each held by a group of theoretical thinkers:

The first is the view that Allah has established evidence by which the truth can be known in every question, so that anyone who exercises independent judgment and expends his utmost effort can ascertain the truth. Anyone who fails to ascertain the truth in a foundational or subsidiary question does so only because he has neglected his duty, not because he is incapable.

This is the well-known position of the Qadariyyah and the Mu‘tazilah. It is also the position of a group of speculative theologians outside these groups. They further say:

As for theoretical questions, there is conclusive evidence by which their truth can be known. Anyone who fails to ascertain it has therefore not expended his utmost effort in seeking the truth and thus incurs sin.

As for practical questions of religious law, they hold two positions:

The first is that these are like theoretical questions: there is conclusive evidence concerning every question, and anyone who goes against it incurs sin. Those who hold this position say that only one person is correct in any foundational or subsidiary question, and everyone other than the person who is correct incurs sin because he is mistaken. In their view, error and sin necessarily go together. This is the position of Bishr al-Marīsī and many of the Mu‘tazilah of Baghdad.

The second is that, if there is conclusive evidence concerning practical questions, then anyone who goes against it