"The argument from queerness" is a term used in the philosophical study of ethics first developed by J. L. Mackie in his book Ethics: Inventing Right and Wrong ISBN 0-14-013558-8 (1977).
Mackie argues against the view that there can be objective ethical values by noting the queer or strange consequences belief in such values implies. The argument is in the form of a modus tollens: If P then Q; but Q is implausible (or "queer"), so P is implausible.
He states that "If there were objective values, then they would be entities or qualities or relations of a very strange sort, utterly different from anything else in the universe" (1977, p. 38). For all those who also find such entities queer (prima facie implausible), there is reason to doubt the existence of objective values.
Argument from queerness Wikipedia
In his book Morality without Foundations: A Defense of Ethical Contextualism (1999), Mark Timmons provides a reconstruction of Mackie's views in the form of the two related arguments. These are based on the rejection of properties, facts, and relationships that do not fit within the worldview of philosophical naturalism, the idea "that everything—including any particular events, facts, properties, and so on—is part of the natural physical world that science investigates" (1999, p. 12). Timmons adds, "The undeniable attraction of this outlook in contemporary philosophy no doubt stems from the rise of modern science and the belief that science is our best avenue for discovering the nature of reality" (1999, pp. 12–13).
The first argument is that our ordinary moral discourse purports to refer to intrinsically prescriptive properties and facts "that would somehow motivate us or provide us with reasons for action independent of our desires and aversions"—but such properties and facts do not comport with philosophical naturalism (page 50).
The second argument is that, if moral realism posits the existence of objective moral properties that supervene upon natural properties (such as biological or psychological properties), then the relation between the moral properties and the natural properties is metaphysically mysterious and does not comport with philosophical naturalism (p. 51).
Also, Timmons says, in connection with both of these arguments Mackie makes the point that a moral realist who countenances the existence of metaphysically queer properties, facts, and relations must also posit some special faculty by which we have knowledge of them (Timmons, p. 51).
In his 1977 book Ethics: Inventing Right and Wrong, Mackie uses these arguments to assert that most moral discourse is flawed because it presumes the existence of moral facts which are not true. He then goes on to propose his own ethical theory, based on an effort to accommodate this deficiency. Mackie's argument from queerness has also inspired fictionalists and has been cited as support for quasi-realism.
Christine Korsgaard (1996) responds to Mackie by saying:
Other criticisms of the argument include noting that for the very fact that such entities would have to be something fundamentally different from what we normally experience—and therefore assumably outside our sphere of experience—we cannot prima facie have reason to either doubt or affirm their existence; therefore, if one had independent grounds for supposing such things to exist (such as, for instance, a reductio ad absurdum of the contrary) then the argument from queerness cannot give one any particular reason to think otherwise. An argument along these lines has been provided by e.g. Akeel Bilgrami (2006).