But while expertise like this is exalted when all that's required is common sense (let them eat chocolate), common sense is exalted, especially by politicians, when what's required is expertise: managing a household budget or even a small business will not help you understand financial markets and the global economy. Exploiting the confused anti-elitism that too often turns ignorance and inexperience into political advantages, these cynical or simply stupid appeals to common sense do resonate politically.
So it's not entirely surprising to hear a lawyer for the conservative Christian Alliance Defense Fund (ADF) assert that commemorating a public war memorial with a giant cross is merely a "common sense idea." He was protesting a 9th Circuit ruling (PDF) that a Latin cross is a sectarian religious symbol, maintained by the state in violation of the First Amendment. Whether the cross is a secular or religious symbol is indeed a question that can be answered with reference to common sense, and the Court answered it correctly, to ADF's dismay.
But common sense will not tell you whether or when the Constitution prohibits government from endorsing and maintaining sectarian religious symbols: that determination requires a measure of expertise and inevitably involves ideology. If the ideal of church state separation, in the interests of religious freedom, is fairly simple and straightforward, the case law interpreting and applying that ideal is voluminous, nuanced, and convoluted. The giant Latin cross case, in particular, Trunk v City of San Diego, has quite a complicated legal and political history that dates back over 20 years (and includes legislation offered by convicted felon and former congressman Duke Cunningham designating the cross a national veteran's memorial.) If the 9th circuit's decision in Trunk is eventually reviewed by the Supreme Court, common sense will have relatively little to do with arguments before the Justices or their rulings on the case.
If you don't study constitutional law, with a particular focus on the First Amendment, until you know it in your bones, you should probably avoid arguing any establishment clauses cases in federal court. Conversely, if you run a nursing home and don't instinctively try to "create positive emotional experiences for Alzheimer's patients," you should probably get out of the business of care giving. Obviously.
You need only a little common sense to know when you should rely on your store of it and when you should develop or seek out expertise. So why are experts often invoked when they're least needed and denigrated when they're needed most? In part, our cultural confusion is a legacy of the inaptly named self-help tradition, which encourages us to rely on self-appointed experts for advice on getting in and out of the rain. As I've frequently observed, personal development authors, "life coaches" and "relationship experts" prosper by mystifying the obvious, packaging, at best, common sense insights as special, secret formulas or "techniques" for achieving mental or spiritual well-being. These experts rarely, if ever, appeal to the intellect. They generally offer to hone our emotional or psychic intelligence, in language easily accessible to anyone with a junior high school education—which makes the celebration of their "expertise" entirely consistent with the denigration of expertise offered by maligned intellectual elites. It may seem counter-intuitive, but anti-intellectualism turns out to be the enemy, not the ally, of common sense.