Raw fear is the greatest reason we act out of self-preservation, but here's another theory: what if the sense of duty causes the greatest fear?
Baruch Spinoza, the eminent Portuguese philosopher of Jewish origin, is attributed as saying that “moral strength, or freedom from the selfish passions, is the virtue of individuals; but security is the virtue of a state.” Spinoza would have known well the concept of moral strength in the face of opposition. The Jewish authorities in Amsterdam issued twenty-three-year-old Spinoza a writ of cherem (excommunication) for alleged heresy. He remained unapologetic for his philosophical writings, however, and accepted the ostracizing from the Jewish community. He probably understood that this censure was handed down to maintain the peace and uphold the faith among the Jews. It was emblematic of the need for security within social institutions.
If you're a student of political theory, you have probably read Thomas Hobbes, the English philosopher. Hobbes brought the concept of fear into the political conversation of European intelligentsia. I think Samuel Coleridge summarizes his most dominant contribution to political thought when he says: “The assertors … consequently ascribe the origin and continuance of Government to fear, or the power of the stronger, aided by the force of custom. This is the system of Hobbes.” Coleridge criticized Hobbes' idea that man's nature is driven by fear of government and a desire for security:
“We are told by History, we learn from our experience, we know from our own hearts, that fear, of itself, is utterly incapable of producing any regular, continuous and calculable effect, even on an individual; and that fear, which does act systematically upon the mind, always supposes a sense of duty as its case.”
Coleridge goes on to argue that a man fears the laws of God and the laws of his country, connecting the sense of duty with the influence of fear on the human psyche via “the invisible powers of our nature, whose immediate presence is disclosed to our inner sense.” Classical liberalism would say that man enters into a contract with the State. But when a group of people are conquered by a foreign ruler, an oath of fealty is asked of them. To Coleridge, this represents the transfer of duty. Why demand an oath from a group of prisoners? Their rights are no longer their own, so they can't freely enter a contract with a new government. Only pure, animalistic fear, then, is inconsistent with the principles of jurisprudence. We operate within the system of laws not solely out of fear as we understand it, but because we have been compelled by a sense of duty to uphold the law. Some anecdotal evidence? Look at the approval ratings of the United States Supreme Court. Regardless of where the approvals of the President and Congress stand, the Court maintains an approximate 20 percent lead. The Court, as a legal and political institution, and a cornerstone of the American Republic, is respected by the people who are subject to its rulings.
We fear the police because we know we have a duty to practice social, civilized behavior and we know that they will act if necessary to uphold that standard. We don't fear the police simply because they have the ability to arrest us. In light of the recent riots in Baltimore, I think it safe to say that Coleridge would remind rioters about their duties as citizens of the United States. Perhaps, then, some issues would be resolved.