Philosophically good is something determined by humans subjectively and consequently is different to every individual with their partial perspective. So really with humanity’s many flaws a true universal common good doesn’t and can’t exist. What can happen is a lot of people can come together in common interest.

Say Iran will nuke Israel. It wouldn’t be a stretch to say it is in every single person’s interest in Israel that they preempt Iran and prevent the existential threat. They’d be sure to express that voluntarily. That’s harmony, and about as pure and just an action a group can take.

Humans being the self-interest motivated being they are seek out advantage, procreation, safety, and stability among other things through just about any means. Through the years the myriads of individuals pursuing these goals have found common interests that benefit all. Boiled down to a simple essence they form the basic rules of society respect private property and respect contracts. Inherently individuals are their own private property. Inherent in respecting contracts is not cheating.

Very conveniently, our society believes in an omnipotent omniscient authoritarian that will save or damn your soul for eternity based on your bad or good behavior. Unfortunately humanity is deeply flawed and inconveniently partial, so conflicts happen. Avoiding physical confrontation at high cost is the third and probably most troublesome rule. *See history of humanity. 

It’s in everyone interest to uphold  and abide by these basic rules. In other words everyone harmoniously believes in basic rule of law. The basic laws being the basic rules no unnecessary physical conflict, respect private property, and respect rule of law. Paramount to note, is that the only people or groups that seek to and do break these rules are the powerful, that believe they can. God used to be more of a deterrent methinks. 

Not only does the “common good” argument used for so much government action(read $pending) make no economic sense, it is morally bankrupt. There is no great concord for social programs, military intervention, taxes, inflationary monetary policy, economic sanctions, environmental “saving” or shenanigans, bailouts, central banking, drug wars, etc etc etc etc (cont 16tril). If there is no great concord for these programs there are large minorities of citizens being disenfranchised, run over, squashed, muted etc etc (cont 49% voting population). If large minorities are disenfranchised we have abandoned our noble principles and are approaching mob or more concentrated rule. Maybe environmental controls are necessary because of a real existential threat, but earnestly there is a larger burden of proof. People are not convinced. Experts one day quacks the next or galileos, get back to us. 

“Common good” is illusionary because it requires there be some objective outside or omniscient power that knows right and wrong for the collective, which is not made up of individuals somehow? . er. . . It’s impossible to rationalize a “common good” from discord or disagreement. If no one agrees that something is good for all, it is not a “common good”. Come on, it’s self-evident.