is Paul speaking of works of the Mosaic Law, or good works in general?
First of all, there is only one law, Gods Law. While Paul has in view the commandments the Jews learned (Romans 3:21), Paul did not forget the parts of Gods Law the Gentiles had, as he specifically mentions them in Romans 3:29-30. Lets assume as true for a second, what some have falsely said, that Paul is only speaking of the Mosaic Law not being able to help merit salvation, and therefore it is possible that good works can partially merit salvation. Now the Mosaic Law did not only say the bad things they could not do, it also specified the good things they should do. If what some have falsely said were true, then the Commandments God gave would not be able to help them merit salvation, but other commandments that God did not give (through forgetfulness, meanness, or some reason) would be able to do so. The root issue here is that there is only One God, and people either are trying to obey or disobey Him. Not only does this verse not show that works can merit salvation, but Ephesians 2