Diversity in the workplace no more ensures equality in the workplace than diversity in general ensures equality in general. Diversity is nothing more than variety. Variety implies differences, and differences, in turn, are a form of inequality. In a workplace setting, the sheer diversity of human resources means that any workforce will have a variety of qualifications. That variety leads to unequal distribution of responsibilities, positions in the hierarchy and opportunity for advancement and higher pay.
There is a logical disconnect in the notion that diversity can ensure equality. The disconnect occurs when we consider that diversity can also encompass culture, education and the intangible qualities of talent and aptitude required to be a success. Equality in the workplace means that everyone in a working environment has an equal chance to be hired, promoted as well as receive equal pay for the same work. In no way, however, can equality (even through diversity) guarantee a successful outcome for everyone. The unrelenting demands of competition and profitability (or cost-effectiveness in the public sector), however, mean that diversity is only effective when it encompasses a mix of talent, abilities and dedication to mission that keeps a company or organization lean and efficient.
Efforts to mandate diversity – that is, requiring employers to achieve employee proportions relative to the population at large – have, in the past, attempted to promote equal opportunity. Requiring active recruitment among groups previously excluded was the stuff of post-civil rights era legislation and affirmative action. They were an attempt to redress centuries-old discrimination against minorities and women.
To the extent that past programs recruited, trained and produced under-qualified people, they unfortunately did a disservice to the system as well as the individual beneficiaries. The "beneficiaries" of imperfectly applied affirmative action programs frequently ended up as administrators and proponents of the very programs that eased them through the educational and hiring system that produced them. We may be on the cusp now where attrition will allow that group to retire in favor of better qualified, less "diversity conscious" successors who have no vested interests in sustaining post-civil rights racial quota programs.
On the other hand, there seems to be an ironic and unintended corollary to "diversity ensures equality." That would be its exact opposite: equality ensures diversity. Past affirmative action and equal opportunity programs have had a jolting, salutary effect on equality in the workplace by mandating diversity. Once the formerly racist and sexist society became accustomed to equal opportunity, acceptance followed in the form of nearly full equality of opportunity and diversity followed as a matter off course.
So diversity in the workplace does not so much ensure equality. Equality is more a by-product, and perhaps an unforeseen result of past programs that made equal opportunity their goal. That goal was sought through paying attention to groups previously exempted from job recruitment. To the extent that paying attention to diversity ensures the best mix of people resources to get the job done, it is a good and worthy goal. But it does not result in equality; it is the natural outgrowth of equality.