Few metaphors could be more appropriate than the "invisible hand" for free market forces, and the constantly shifting school choice movement over the past thirty years (paralleling the accountability era spurred by A Nation at Risk) reflects how choice advocates are driven by ideology and faith in market forces regardless of evidence.
Lubienski and Weitzel (2008) examine school choice advocacy and offer this key point:
This is a notable possibility in view of the claim that voucher programs have not been shown to harm academic achievement. In fact, the “do no harm” promise is far removed from earlier claims about the potential for vouchers to improve student performance. Over a decade into this reform, some advocates are moving away from optimistic claims about school choice achievement outcomes, and many are instead highlighting parent satisfaction as evidence of success. (p. 484)
In the 1980s and 1990s, before a substantial body of research had emerged, vouchers were heralded as the panacea for a failing public school system. Once the shine wore off those lofty claims--since research shows little to no academic gains driven by any choice initiatives--school choice advocates began to change claims and approaches, attempting to stay at least one step ahead of the evidence throughout the process.
The evolution of the school choice advocacy talking points has included the following, in roughly the order in which they surfaced in the advocacy reports by think tanks and the media from the 1980s until 2011:
• Public education is a failure because it is a monopoly, and market forces can and will eradicate the problems posed by a monopoly. Vouchers are the solution to public education failures because they will force public schools to compete with superior private schools.
(Subsequently, vouchers proved to be unpopular with the public, and private schools were revealed to be little different in effectiveness than public schools when student populations were taken into account.) 
• No vouchers, then let's use tuition tax credits. . .
• How about public school choice then. . .?
(See evidence from Milwaukee, Minnesota, and Florida--where widespread choice and choice tied to accountability have neither raised achievement nor actually spurred any real competition.) 
• Then, how about charter schools. . .and let's be sure to address children and families in poverty. . .and parents really are happy when given choice. . .and choice might raise graduation rates. . .
• But vouchers/choice "do no harm"! 
• Why would anyone want to deny choice to people in poverty, the same choice that middle- and upper-class people have?
And that is where we stand today in the school choice advocacy discourse. The newest talking points are "do no harm" and that people apposing vouchers want to deny choice to people living in poverty.
And throughout the school choice debate, ironically, the choice advocates shift back and forth about the rigor of research--think tank reports that are pro-choice and the leading school choice researchers tend to avoid peer-review and rail against peer-reviews (usually charging that the reviews are ideological and driven by their funding) while simultaneously using terms such as "objective," "empirical," and "econometrics" to give their reports and arguments the appearance of rigor.
But, if anyone makes any effort to scratch beneath the surface of school choice advocacy reports, she/he will find some telling details:
In education, readers should beware of research emanating from the Hoover Institution at Stanford University, the Heritage Foundation, the Manhattan Institute, the Heartland Institute, the Mackinac Center, the Center for Education Reform, the Thomas B. Fordham Foundation, the American Enterprise Institute, the Paul Peterson group at Harvard, and, soon, the Department of Education Reform at the University of Arkansas. Arkansas is home to the Walton family, and much Wal-Mart money has already made its way to the University of Arkansas, $300 million in 2002 alone. The new department, to be headed by Jay P. Greene, currently at the Manhattan Institute, will no doubt benefit from the Walton presence. The family’s largesse was estimated to approach $1 billion per year (Hopkins 2004), and before his death in an airplane crash, John Walton was perhaps the nation’s most energetic advocate of school vouchers. (Bracey, 2006, p. xvi) 
School choice may, in fact, hold some promises for reforming education since "choice" is central to human agency and empowerment. But the school choice movement and its advocates are the least likely avenues for us ever realizing what school choice has to offer because the advocates are primarily driven by ideology and funding coming from sources that have intentions that have little to do with universal public education for free and empowered people.
And the growing evidence that corporate charter schools as the latest choice mechanism are causing harm--in terms of segregation and stratification of student populations--is cause for alarm for all people along the spectrum of school reform and school choice. 
If a school choice advocate sticks to the talking-points script and will not acknowledge the overwhelming evidence that out-of-school factors determine student outcomes, that evidence is mounting that choice stratifies schools, and that evidence on how school is delivered (public, private, charter) is mixed and similar among all types of schooling, then that advocate isn't worth our time and isn't contributing to a vibrant and open debate that could help move us toward school reform that benefits each student and our larger society.
 Braun, H., Jenkins, F., & Grigg, W. (2006, July). Comparing private schools and public schools using hierarchical linear modeling. National Center for Educational Statistics. Washington, DC: U.S. Department of Education. Retrieved 28 December 2008 from http://nces.ed.gov/... Lubienski, C., & Lubienski, S. T. (2006). Charter, private, public schools and academic achievement: New evidence from the NAEP mathematics data. Retrieved 28 December 2008 from the National Center for the Study of Privatization in Education Web site: http://www.ncspe.org/... Wenglinsky, H. (2007, October). Are private high schools better academically than public high schools? Retrieved 28 December 2008 from the Center for Education Policy Web site: http://www.cep-dc.org/...
 Dodenhoff, D. (2007, October). Fixing the Milwaukee public schools: The limits of parent-driven reform. Wisconsin Policy Research Institute Report, 20(8). Thiensville, WI: Wisconsin Policy Research Institute, Inc. Retrieved 6 August 2009 from the Wisconsin Policy Research Institute Website: http://www.wpri.org/... Witte, J. F., Carlson, D. E., & Lavery, L. (2008, July). Moving on: Why students move between districts under open enrollment. Retrieved 6 August 2009 from the National Center for the Study of Privatization in Education Web site: http://www.ncspe.org/... Failed promises: Assessing charter schools in Twin Cities. (2008, November). Minneapolis, MN: Institute on Race and Poverty. Retrieved 6 August 2009 from: http://www.irpumn.org/... Belfield, C. R. (2006, January). The evidence of education vouchers: An application to the Cleveland scholarship and tutoring program. Retrieved 6 August 2009 from the National Center for the Study of Privatization in Education Web site: http://www.ncspe.org/... Bell, C. A. (2005, October). All choices created equal?: How good parents select “failing” schools. Retrieved 6 August 2009 from the National Center for the Study of Privatization in Education Web site: http://www.ncspe.org/...
 Lubienski, C., & Weitzel, P. (2008). The effects of vouchers and private schools in improving academic achievement: A critique of advocacy research. Brigham Young University Law Review (2), 447-485. Retrieved 26 April 2011 from http://lawreview.byu.edu/...
 Bracey, G. W. (2006). Reading educational research: How to avoid getting statistically snookered. Portsmouth, NH: Heinemann.
 Fuller, E. (2011, April 25). Characteristics of students enrolling in high-performing charter high schools. A "Fuller" Look at Education Issues [blog]. Retrieved 26 April 2011 from http://fullerlook.wordpress.com/... Miron, G., Urschel, J. L., Mathis, W, J., & Tornquist, E. (2010). Schools without Diversity: Education management organizations, charter schools and the demographic stratification of the American school system. Boulder and Tempe: Education and the Public Interest Center & Education Policy Research Unit. Retrieved 26 April 2011 from http://epicpolicy.org/... Miron, G., Urschel, J. L., & Saxton, N. (2011, March). What makes KIPP work?: A study of student characteristics, attrition, and school finance. Teachers College, Columbia University. National Center for the Study of Privatization in Education. Retrieved 26 April 2011 from http://www.ncspe.org/... Miron, G. & Urschel, J.L. (2010). Equal or fair? A study of revenues and expenditure in American charter schools. Boulder and Tempe: Education and the Public Interest Center & Education Policy Research Unit. Retrieved 26 April 2011 from http://epicpolicy.org/... Frankenberg, E., Siegel-Hawley, G., Wang, J. (2011) Choice without equity: Charter school segregation. Educational Policy Analysis Archives, 19(1). Retrieved 26 April 2011 from http://epaa.asu.edu/... Baker, B.D. & Ferris, R. (2011). Adding up the spending: Fiscal disparities and philanthropy among New York City charter schools. Boulder, CO: National Education Policy Center. Retrieved 26 April 2011 from http://nepc.colorado.edu/...