You’re a sensible, principled conservative. You want America to be a land of boundless opportunity and freedom, where people are treated as individuals and judged on their merits. You reject the divisive identity politics of the left - what matters most about any of us, you would insist, is not race or class or ethnic origins: it is personal character and achievement. There are few things about contemporary politics you deplore more than the demonizing or scapegoating of entire groups (“white males,” “the rich,” “the Christian right,” “gun owners”), as though every member of the group is interchangeable and indistinguishable, wholly defined by a single disparaging label.

But let someone mention “illegal immigrants,” and your principles fly out the window.

So when Governor Deval Patrick recommends allowing young illegal immigrants - residents of Massachusetts who have graduated from high school - to attend a public college and pay in-state tuition, you flip out. This is outrageous, you protest. It rewards people who broke the rules. It’s unfair to the taxpayers who subsidize public higher education. Why should an illegal immigrant get a valuable tuition break that Massachusetts wouldn’t give to a kid from Maine or New Hampshire?

You vigorously agree with Charlie Baker, a Republican candidate for governor. “If you’re illegally here, you’re illegally here,” Baker said last week. “The notion that we should treat illegal immigrants with the same benefits and opportunities that legal immigrants and legal citizens have doesn’t make any sense to me.”

It is dispiriting to see Baker, a man of considerable intellectual heft, stoop to such shallow sloganeering. It is even more dispiriting to see conservatives assail immigrants instead of the insane immigration system that gave most of them no legal way to enter the United States. On the whole, illegal immigrants are just the sort of newcomers Americans should embrace: self-motivated risk-takers, strivers determined to improve themselves, hard-working men and women willing to take the meanest jobs if it will give them a shot at building their own American dream. Why would we want to punish them? Why would we want to punish their kids?

A couple from Brazil, seeking a better life for themselves and their 2-month-old daughter, enter the United States unlawfully. They settle in Massachusetts, where 18 years later the girl graduates from a public high school, as assimilated and acculturated an American as her classmates in every respect - except that they are US citizens, and she, by virtue of a decision made when she was a baby, is not. Her classmates can attend the University of Massachusetts, paying $9,704 a year in tuition, the price tag for Massachusetts residents. She can attend only if she pays the out-of-state rate of $22,157; if that’s more than she can afford, she’s out of luck.

How is that a rational public policy? How is Massachusetts improved by making it impossible for an accomplished high-school graduate, a lifelong resident of the state, to gain a university degree? Who benefits when her education - along with the higher earning potential it would lead to - is cut short? She doesn’t. You don’t. Massachusetts taxpayers certainly don’t.

Those taxpayers, remember, include illegal immigrants. More than two-thirds of illegal immigrants pay Social Security and income taxes. Between 1996 and 2003, payments from tax filers using Individual Taxpayer Identification numbers - a nine-digit substitute issued by the IRS for taxpayers ineligible for Social Security - totaled $50 billion. More than 35,000 such taxpayers, most of them illegal immigrants, annually file returns in Massachusetts.

If Republicans really believe, as Baker says, that “it doesn’t make any sense” to allow illegal immigrants to enjoy the same benefits as other state residents, why stop with in-state tuition? Why not bar them from driving on state highways? From camping in state parks? From using libraries?

Of course illegal immigration is a problem. But it can only be solved by overhauling our dysfunctional immigration laws, not by demonizing or scapegoating illegal immigrants. Those immigrants didn’t come here in order to be lawbreakers; they broke a law in order to come here. That’s a distinction with a crucial difference - one that sensible and principled conservatives should be able to understand.