Often, when talking with people who identify themselves as "pro-choice," they'll state that unborn children represent "potential life," but they'll argue that the value of those "potential lives" is outweighed by the health and happiness of the mother.
Pro-life people have correctly responded to such statements by saying that unborn children are not "potential lives". They are "lives with great potential".
If I were to describe John McCain as a "potential president," or to describe Barack Obama that way, that would make sense, because there is a reasonable possibility that either one of those men might become President (provided that claims that Obama isn't a native-born citizen of the United States prove to be unfounded), but neither one of those men has won the election yet, so neither one is currently the President.
If I described a person who wasn't born in the United States as a "potential president," it would clearly be a false claim, at least insofar as our current laws are concerned, because foreign-born people are ineligible to serve as President. Therefore they are not potential presidents, and they never will be unless our laws are changed.
Conversely, it would be stupid to say that George W. Bush was a potential President. He was a potential president prior to being elected. When he was elected, he stopped being a "potential president" and became our President (notwithstanding wishful thinking on the part of the Democrats to the contrary). During his first term, he was technically both a "potential president" and a "president", inasmuch as he had the potential to be re-elected, and he was also the President at the time. But no one in his right mind would have described him as a "potential president" at that time, because the most important aspect of his identity was not what he might later become, but what he already was.
It's difficult to know what to make of liberal claims to the effect that unborn children represent "potential life". If they aren't biologically alive, the likelihood that they will ever become biologically alive is scientifically nil. (Biological life does not spring forth from inanimate matter or from biological death, unless one is talking about miraculous events such as the creation of the first man from dust or the resurrection of Christ.) On the other hand, if unborn children are biologically alive, then why not just say so? Intellectually speaking, the description of unborn children as "potential lives" is incoherent --- unless one defines human life in a manner which has little or nothing to do with biology.
The real issue here is that liberals have managed to invent a value system in which being biologically alive and being undeniably human in terms of one's genetic structure are both considered insufficient for the purpose of procuring the legal right to life. Instead, such people have added a host of additional arbitrary criteria (pertaining to such things as communicative abilities, cognitive abilities, social relationships and so forth), without which biologically alive entities who are indisputably human beings in the genetic sense are merely considered to be "potential lives" for legal purposes.
By calling the unborn child "potential life," people who favor legal abortion deliberately seek to diminish our awareness and appreciation of the value of the unborn child, and to imply that we should accept a prorated value system in which some people who are indisputably human and indisputably biologically alive are considered to be less valuable than others fitting that description.
This, of course, makes a mockery of the Declaration of Independence, which says that all people (or "men," in the parlance of the day) are "created" (not born) equal.
People are not "created" at birth. They are created at the moment when they are first conceived. That's a biological fact, not a matter of philosophy or religious dogma.
Attempts to obfuscate the issue by talking about how unborn children are not fully developed ignore the demonstrable fact that human development is a continual process which does not by any means end at birth. If indeed being "fully developed" is the prerequisite for the legal right to life, then none of us is safe from the destructive impulses of the would-be murderer.
The trouble with most attempts to justify legal abortion is that they rely, in large part, on the willingness of the American public to accept simplistically deceptive marketing slogans without giving much thought to what those slogans really mean and imply. Just as the word "choice" has been used as a euphemism in order to cause people to overlook the demonstrable fact that there are cases in which it is legitimate and necessary to restrict choice in order to protect the rights of others, so also the phrase "potential life" has been used in order to pull the wool over people's eyes and cause them to support policies which are in direct contradiction of the values upon which our nation was founded.