I wanted to quickly relate an interesting question one of my students asked me. I believe the answer to that question is an important though often overlooked idea.
I was discussing the idea of God's justice - as explained in Rambam (sticking to the MT to keep things simple) - namely, the idea that "כל-דרכיו משפט". I told them that we know God is absolutely just - He relates to every single individual in accordance with his z'chuyot and avonot. However, only God can weigh an individuals z'chuyot and avonot so only He can say what is just for each individual (nothing original here - I was just paraphrasing Rambam in Hilchot Deot Chapter 3). I made a comparison between the laws of nature that we can discover and then use to explain natural phenomena and the "laws" of hashgacha that we can know in a general sense but can not use to explain the "human phenomena".
Then one of the students raised the following difficulty:
If we believe in b'chira then consider the following case: Levi wants to kill Shimon but God has determined that it is not just for Shimon to die. So in line with "כל-דרכיו משפט" God will prevent Levi from killing Shimon but that would contradict Levi's free-will.
What the student did not understand is that b'chira has nothing whatsoever to do with freedom of motion or action. B'chira is the choice between being good or being evil. In the students example Levi's choice to do evil was not withheld from him only the fulfillment of that choice was withheld. If Levi is not successful in killing Shimon does that make the act any less evil? I believe a careful reading of the fifth chapter of Hilchot Deot will make this point even clearer.