According to Islamic Psychology, do we have the inherent ability of recognizing the good from the evil?
Yes, we do have the inherent ability to recognize good from evil. The fitrah is proof of this. It is also mentioned in Imam an-Nawawi's hadeeth collection:
“Seek judgment from your heart." 
One has the inherent ability to differentiate good from evil, except if one's fitrah is corrupt.
There is an interesting study proving that babies as small as 6 months can tell the difference between good and evil: http://www.dailymail.co.uk/news/article-1275574/Babies-know-difference-good-evil-months-study-reveals.html
Here is the exegesis of Imam ibn Kathir regarding the issue:
(By Nafs, and Ma Sawwaha (Who apportioned it).) meaning, He created it sound and well-proportioned upon the correct nature (Al-Fitrah). This is as Allah says,
فَأَقِمْ وَجْهَكَ لِلدِّينِ حَنِيفاً فِطْرَةَ اللَّهِ الَّتِى فَطَرَ النَّاسَ عَلَيْهَا لاَ تَبْدِيلَ لِخَلْقِ اللَّهِ
(So set you your face towards the religion, Hanif. Allah's Fitrah with which He has created mankind. No change let there be in the Khalqillah.) (30:30) The Messenger of Allah (ﷺ) said,
“Every child that is born, is born upon the Fitrah, but his parents make him a Jew, a Christian, or a Zoroastrian. This is just as the animal is born, complete with all of its parts. Do you notice any mutilation in it?” 
And Allah knows best.
 [An-Nawawi, hadeeth no. 27. It is a good hadith transmitted from the Musnads of the two Imams, Ahmad bin Hanbal and Al-Darimi]
 [Narrated by al-Bukhaari, 1296; Muslim, 4803]< Back to Questions