The most important contribution to world culture of the Enlightenment was the promulgation of a set of important ideas and values, most notably those of freedom/liberty/autonomy and equality. These are ideals that have continued to have value well beyond the specific 18th/early 19th century period usually referred to as “The Enlightenment,” so that we can speak of an ongoing “Enlightenment Project” of implementing these basic ideals. (There were/are varieties of Enlightenments and Enlightenment Projects. Associated with the French Revolution was the famous triad of liberty, equality, fraternity. Coming much later, but still very much associated with the continuing project of expanding freedom, the Mexican revolutionary Emiliano Zapata emphasized land and liberty, the emphasis on both the ideal and the material condition necessary to implement it. In the U.S., liberty/freedom has been especially foregrounded as an ideal. Equality of opportunity and equality before the law have been generally held ideals, while equality of social condition has not been as widely held as an ideal, and the French “fraternity” is largely absent from consideration.)
In practice, Enlightenment values have always been coupled with contradictory practices, e.g. practices of slavery and Jim Crow laws alongside values of equality and freedom.
As a matter of historical or social analysis, these contradictions between ideals or values and practices must remain coupled. Both are part of historical or current social realities.
Further, refusing to decouple Enlightenment values from contradictory practices enables us to better understand things like racist thinking associated with slavery and/or colonialism and their aftermaths. These are syntheses of the contradiction between values and practices. Much scholarship on race in early colonial North America indicates that masters felt no particular need to distinguish greatly between white and black forced laborers, nor a particular need to defend such practices. Racism grew up alongside developing notions of freedom and equality. As the radical inequality associated with forced labor began to seem wrong, but the profits generated were hard to pass up, the development of notions of inherent racial inequality served as useful rationalization – one could treat some unequally because regarded as naturally unequal.
A similar type of thinking developed concerning gender and the growing contradiction between the value of equality and realities of gender inequality. In an engaging essay, “Orgasm, Generation, and the Politics of Reproductive Biology” (the essay can be found in The Gender/Sexuality Reader, edited by Roger Lancaster and Micaela di Leonardo), Thomas Lacqueur discusses changes in scientific thinking about female and male reproductive anatomy and physiology in the late 18th/early 19th century. Earlier, it had been typical to think of males and females as manifesting degrees of difference along a continuum, with this related to a lingering humoral conception of the body. Male and female genitalia were thought of as the same structures, for example, with “hotter” male bodies extruding the genitalia and cooler female bodies having the same reproductive structures introverted, i.e. females were males inside-out, or perhaps outside-in. Beginning in the late 18th century, males and females began to be seen more and more as different species in terms of their biology, with females’ rationality in particular being affected by menstrual cycles.
As a matter of values for ongoing scholarship and engagement with the world, though, historical and current contradictions between ideals and practices should be decoupled. I don’t mean that practices, now or in the past, that contradict the values of freedom and equality should be ignored, forgotten, justified, or anything of the sort. Far from it. I mean that contradictory practices in themselves don’t undermine or invalidate the values.
The fact that Thomas Jefferson was a slaveholder doesn’t undermine his words regarding liberty and equality. It makes him a hypocrite, something he himself was aware of, but it doesn’t and shouldn’t make his words in the Declaration of Independence any less stirring (nor do you have to be a communist to be stirred by the evocation of those very words by Ho Chi Minh against French colonialism in the mid-20th century). Nor was his slaveholding a part of an Enlightenment Project. Instead, this was a practice resisting such a project and contradicting his own stated values.