What is the meaning of "Ein Na'aseh Pisgam Ma'ase ha'Ra Meherah"?
Rav Sadya Gaon: Since there is not immediate punishment for evil deeds [people have courage to do evil]. Rashi - "Pisgam" is judgment. People say that there is no judgment.
Rid: Resha'im are not judged in this world.
Rashbam: Pisgam is Davar. (Nothing is done quickly to punish evil deeds.)
Why does it say "Al Ken Malei Lev Bnei ha'Adam Bahem La'asos Ra"?
Ibn Ezra: People desire to do evil, for fear departs from them.
Rid: They think that the world is Hefker, because sinner and Rasha do 100 evils, and Hashem delays anger and does not take vengeance in this world.
Seforno: They think that they will not receive any punishment.
Orchos Tzadikim (Sha'ar ha'Teshuvah DH ha'Revi'i Tzarich): May think that sins will be forgotten and there will not be judgment on them.
Metzudas David: They think that there is no supervision and no judgment.