We run into two kinds of common sense the true and the false. The former referenced above by Mark Twain, a common sense that is fact; simple and self evident. The other has no author to proclaim it. The common sense of belief; tortured explanation and dedicated purpose. The first born out of observation, the second, shortly there after from need.
Common sense is wearing a seat belt when you drive a car. Why? Because when your vehicle goes from 50 kph to 0 kph it will keep you from being smashed into the dash. Wearing a seat belt will save your life. If you you go out on a boat you wear a life vest. Why? Because people drown in water, life vests help to keep your head above the water. Wearing a vest will keep you alive.
The hallmark of common sense, is that it requires, no privileged perspective, special knowledge or lengthy explanation. It is on its face obvious. It is a true thing, independent of personal desire. Which is not to say it is universally hailed or agreed upon, common sense is not a compulsion, people are free to do what the like. We all know people that won't wear seat belts or life vests.
The utility of common sense is limited because it is factual and uncomplicated. It has limited use in persuasion unless your position is the correct one. Unless you change to what common sense is. Here is where it is transformed from fact to belief. Common sense of belief has a wider application because it conforms to your position. This comes at a cost. Common sense of belief is assailable. It is identifiable by the complicated nature of its "truth". If it requires a lengthy explanation, narrow perspective and specialized knowledge; chances are it's belief driven.
More guns mean less crime, more gun regulation means less crime; both will be touted as common sense positions, neither are, it's too complicated an issue. Marriage is only for heterosexual couples, safe injection sites promote drug use or welfare keeps people from working, longer prison sentences lower crime rates, higher taxes hurt job growth. It is no surprise that political and social conservatives, religious institutions and corporation are more prone to abusing "common sense" than the centre or the left, though the centre is quite capable of it too. In part because conservatives tends to favour restricting rights, punitive actions and the preservation of privilege. These positions are often laboured and require quite a bit of work to resemble common sense in any way.
What the reader should understand is that you are always being sold something. Rendering the complicated into the simple is just a sales tool. It is your job to be critical. When offered a truth take it apart. Be skeptical, the more so if you like what your hearing. After all
"Common sense is not so common." * Voltaire, Dictionnaire Philosophique (1764)