Although it sometimes appears, at least on a cursory reading, that the arrangement of the various laws in Sefer Devarim is completely random, with in-depth study and an understanding of the text, various connections appear, tying together otherwise disparate subjects to teach a greater moral or spiritual lesson.
Such is the case with the final three mitzvos in this parashah. They are, in order:
"When men strive together one with another, and the wife of the one draweth near to deliver her husband out of the hand of him that smiteth him, and putteth forth her hand, and taketh him by the secrets; then thou shalt cut off her hand, thine eye shall have no pity." (25:11-12)
"Thou shalt not have in thy bag diverse weights, a great and a small. Thou shalt not have in the house diverse measures, a great and a small. A perfect and just weight shalt thou have; that thy days may be long upon the land which the Lord thy God giveth thee. For all that do such things, even all that do unrighteously, are an abomination to the Lord thy God." (25:13-16)
"Remember what Amalek did until thee by the way as ye came forth out of Egypt; how he met thee by the way, and smote the hindmost of thee, all that were enfeebled in thy rear, when thou wast faint and weary; and he feared not God. Therefore it shall be, when the Lord thy God hath given thee rest from all thine enemies round about, in the land which the Lord thy God giveth thee for an inheritance to possess it, that thou shalt blot out the remembrance of Amalek from under Heaven; thou shalt not forget." (15:17-19)
Now what do these three mitzvos have in common with each other? At first glance, nothing. One is about physical assault, the second about business ethics and the third a call to genocide. However, if one examines the details of each mitzvah closely, a pattern does emerge.
In the first case, the Torah tells us that a woman seeking to save her husband from being beaten up is not allowed to simply grab the assailants scrotum and give it a good yank. Now Chazal, on analyzing this law, note that there is one specific limitation to it: she must have had another way to save her husband but chose instead to assault the man's groin. If the only option she had was to kick him in the crotch, then the law does not apply. Rav Shimshon Rafael Hirsch, in his commentary on the verse, notes that the reason for this is that the underlying reason for the stiff penalty, which incidentally means monetary compensation and not real amputation, is because the woman elected to save her husband in a way that completely humiliated his assailant. And lest one think that this is acceptable, the Torah precedes this law with the one about yibum where the yevamah is indeed enjoined to humiliate her brother-in-law when he declines to marry her. There she is allowed to, but only because the Torah makes an exception. In this case, although she needs to save her husband, she cannot ignore the concept of human dignity in doing do.
The second mitzvah, that of just measures, also carries a ssecond meaning with it. On the surface the law makes obvious sense. Don't cheat your fellow. Simple, yes? Many commentaries take it further that in all aspect of business a Jew must keep to the highest ethical standard. After all, the Torah doesn't say "have fair weights" but calls them just and perfect. But consider that despite this seeming simplicity, this law is quite often ignored in practice. After all, who other that you knows if you're using loaded weights? Many otherwise frum people, some of them prominent religious figures, have no trouble taking shortcuts with the system. The same person who will not touch a piece of food that isn't double-glatt mehadrin min mehadrin might have no problem getting yeshivah students to try and smuggle drugs into a foreign country.
The psychology behind this is fascinating but not new. The gemara relates a story about Rabban Yochanan ben Zakai who, on his deathbed, was asked for a blessing by his students. "May your fear of God be as great as your fear of man," he offered. "Not more?" they asked. "People always think about sinning and look around to make sure no one can see them," he explained, "and they seem to forget that God is always watching."
Thus the first mitzvah, not humiliating one's fellow deals with the Torah's expectations for us in the category of ben adam l'chavero. The second mitzvah, honesty in business, deals with the category of ben adam l'Makom. Your fellow may never discover you cheated him but God knows.
And together, these two interpretations tie into Amalek. Now, for those who believe the Torah is calling for genocide, one must understand that this particular interpretation of the mitzvah is impossible to fulfill nowadays. Chazal tell us that when Sancheriv conquered the Middle East, he displaced all the nations and nowadays no one can be sure what nation he originally came from. Even someone claiming to be from the land of Amalek would not be considered an Amaleki for the purposes of this mitzvah.
Yet this mitzvah, which we still read on Shabbos Zachor every year, must still have some relevant use for us today. Why would we continue to discuss our desire to destroy a nation which no longer exists?
One must therefore understand that Amalek is no longer a nation in particular but rather the values that this nation represented. And what are those values? In this short paragraph, the Torah gives us two: (1) how he met thee by the way, and smote the hindmost of thee, all that were enfeebled in thy rear, when thou wast faint and weary; (2) and he feared not God.
Now the connection to the preceding two mitzvos is clear. The first quality of Amalek parallels the mitzvah of not humiliating one's fellow. The second concerns fear of God. Amalek represents the person, nation or culture that denies the holiness intrinsic in every human being as well as the presence and benificence of God in our lives. It is our duty as Jews to remove these characteristics from the world. Not through slaughtering those who embrace them but by working to create a society in which those values have no place. As the Gemara tells us, we should always pray that sin disappears from the world, not the sinners themselves for through their teshuvah we bring the world one step closer to its final redemption.