When you break something at home, it may be sheer carelessness. But when the person who doing the breaking is Moses, and what he breaks is the tablets of the Ten Commandments, he surely knows what he is doing.
The sidra tells the story. The people have forgotten God and are dancing round a golden calf; Moses sees the sight when he descends from Sinai and he shatters the tablets of the Decalogue which God Himself had engraved (Ex. 32:19). Surely Moses knows the law of bal tash’chit - “you shall not destroy” (based on Deut. 20:19)! This is not a cup or saucer he was breaking, but the tablets of the covenant!
Some say his action was involuntary. So shocked was he at the sight of the golden calf that he lost his physical strength and the tablets dropped from his hands. It seems more likely, however, that his action was deliberate. Rashi thinks that Moses said, “The people have become apostates, and how can they have any share in the Torah?” Abravanel suggests that he broke the tablets to shock the people and bring them to their senses.
Avot D’Rabbi Natan, on the other hand, believe Moses was trying to lessen the severity of their sin; it was like tearing up a contract so that whatever one party does will be less evidently a breach. The Midrash says that he was throwing his lot in with them; by shattering the tablets he was in effect saying to God, “They have sinned; I too have sinned forgive both of us or neither!”
Whatever his motive, God approved and congratulated him, saying, Yeyasher kochacha sheshibarta - “Well done that you broke them!” (Rashi on Deut. 34:12). Another great figure who took drastic action and gained Divine approval was Pinchas the priest, who saw immorality in the camp and risked losing his priestly status because he indignantly slew those responsible (Num. 25). Instead of stripping him of his rank God said, “I give him My covenant of peace” (Num. 25:12).
But these precedents are not to be taken as a blank cheque for violent demonstrations or taking the law into one’s own hands. Moses and Pinchas were exceptional individuals and no-one has the right to expect the Divine approval they received. The general Jewish ethic of protest requires respect for the law and the principles of democracy. There is a duty to cry out, but one must not play God. “A time to act for the Lord” (Psalms 119:126) must not become “a time to be the Lord”.