While a charge of inconsistent application of principles can be problematic, there are a variety of ways to reply. Some of these go beyond the domain of good logic and include such tactics as lying and rhetoric. Other ways to reply fall within the realm of good reasoning and I will discuss those. To focus the discussion, I will present an example that will be used to illustrate the various options.
Suppose that Barbara and Bill are watching a TV news segment about male-only country clubs. A devoted feminist, Barbara argues that this exclusivity is morally wrong and that these clubs should be legally required to admit women. Shortly after Barbara finishes her argument, an ad for a gym that is exclusive to women appears on TV. A look of inquiry on his face, Bill turns to Barbara. Powered by righteous fury, she claims that women should be allowed to work out in spaces that exclude male gawkers.
If Barbara’s principle is that exclusion based on sex is immoral, then she is not applying the principle consistently. This is because it is applied one way to men, another to women. Thus, her application is flawed and subject to criticism on the grounds of this inconsistency. Fortunately for Barbara, she does have some options when Bill points out her apparent inconsistent application.
One response, which is rarely used, is to admit the inconsistency and start applying the principle in a consistent manner. In this example, Barbara would have to accept that if male-only county clubs are wrong, then so are female-only gyms.
A second response is to try to dissolve the inconsistency by showing the alleged inconsistency is merely apparent. This is usually done by showing that there is a relevant difference between the applications. Returning to the exclusion based on sex example, the alleged inconsistency could be dissolved by arguing that country clubs are relevantly different from gyms or that men are relevantly different from women in this case. For example, it could be argued that men are more likely to harass women in the gym then women are likely to harass men in a country club. Successfully arguing for either of these would justify the difference in application and hence defeat the charge of inconsistency. This is because the application is only inconsistent if the situations are morally the same.
A third way to reply is to reject the attributed principle. When people apply their principles, they rarely spell out the principle they are using. As such, one must often infer the principle being used based on what the person says. Unfortunately for sorting out the principle in use, it is usually the case that multiple principles are consistent with the evidence at hand.
Using the inequality example presented above, a Barbara could claim that Bill is wrongly attributing to her a principle of equality and her actual principle justifies the difference in her views. For example, her principle might be that women should be treated equally except when it is to their advantage to be treated differently. Alternatively, she might claim that her actual principle is that people should not be discriminated against except in cases in which the presence of one gender would create undue discomfort to the other gender. The actual principle is, of course, still subject to evaluation. For example, the principle that allows women to be treated unequally when doing so is to their advantage would seem to be morally problematic. The other principle is less problematic and is, in effect, a relevant difference argument.
A final, somewhat extreme, method of replying is to reject the entire notion of consistent application and embrace the “principle” of just doing whatever one wants in each situation. To do this is to be unprincipled, which seems morally problematic.
The wizard Arrogo, a student of the infamous mage Kelok, achieved minor fame developing original spells, some of which were extremely dangerous to the caster. While his supporters claim he developed spells still used today, unbiased experts claim his original spells have been lost. His detractors claim that this is a good thing, at least for wizards who prefer not to be imploded by their own magic.
Old stories tell of the wizard Kelsun, better known as Kelsun the Mad Prophet, who was driven mad by visions of a world-shaking disaster. Fortunately, his madness proved to be benevolent—he set out, in his odd way, to help ensure that items of power would be available to help rebuild civilization after the disaster. Unfortunately, his benevolent madness was…madness. He created strange dungeons filled with exotic traps and monsters to guard these items. As most dungeon creators do, he left cryptic and even bizarre clues regarding the locations of his caches.