If, when in a four-rak'ah prayer, a worshiper doubts whether the tashahhud is the first or the second, should he base his decision on the greater number, or on the lesser number as a precaution?

The majority of jurists hold that whoever doubts the number of rak'ahs (units of prayer) or the tashahhud (testification of faith) should base their decision on the lesser number, then perform the two prostrations of forgetfulness (sujood as-sahw) before the salaam (final salutation). However, some scholars, including Ibn Taymiyyah and Ibn 'Uthaymeen, were of the view that one should strive to ascertain what is correct and act upon what they predominantly believe to be true, then perform the two prostrations of forgetfulness after the salaam. As for someone who is frequently afflicted by doubt, they should disregard it and build upon the greater number. And if they build upon the lesser number, it is permissible and their prayer is valid.