This is first and foremost a blog dedicated to philosophy and theology. With that said, I won't actually be endorsing any political view in this post. Whether our borders should be closed or not, whether illegal immigrants should be deported or given amnesty, etc., is entirely beyond the scope of what I'm about to argue.
What the opponent of illegal immigration argues is this:
1. Those who do not enter the U.S. legally should not be granted amnesty. (Premise)
"Amnesty," in this context can be used broadly. Of course, it is not always used this way, but it can refer to any action (or lack thereof) that results in the absence of discipline for those who enter our country illegally.
2. Persons X, Y, and Z have entered the U.S. illegally. (Premise)
The discussions most often refer to our neighbors to the south, in Mexico. There are approximately eleven million illegal immigrants from Mexico, so most of the news coverage focuses on this demographic.
3. Therefore, persons X, Y, and Z should not be granted amnesty. (Conclusion)
Now, whatever you think of this argument, it is clearly valid. Premise (2) isn't even up for debate, since we have laws governing immigration in our country and there are some who have not obeyed these laws. (Maybe the laws should be changed? I leave it to the reader to decide.)
The controversial premise, of course, is (1). There are many who believe that anything less than amnesty, or something less than full-blown deportation or criminal charges, are either morally wrong or impractical. This is a debatable point. However, it is often asserted:
4. Those who believe (3) are racist. (Premise)
5. Therefore, (3) is wrong. (Conclusion)
Obviously, (5) does not logically follow from (4). Even assuming that those opposed to illegal immigration are the most bigoted, racist members of the Ku Klux Klan, it doesn't follow that their arguments against illegal immigration are incorrect.
To put it another way, X cannot justify action A by appealing to the wrongdoing of action B. Racism and bigotry are morally wrong. (I'm glad I could get that out of the way.) But, even granting that many (most? all?) who are opposed to A also engage in B, it doesn't follow that the arguments against A are thereby invalidated.
What I propose is nothing more than a principle we're all taught in kindergarten: play nice. Let's focus on the issues, and not on the persons who adhere to them.