On The Logical Impossibility of Moral Intuition
Intuitionist ethics rests itself upon the notion that non-natural qualities such as "goodness" and "beauty" can be, in a loose sense, perceived through some faculty of intuition. For my part, I believe that these moral apprehensions described by intuitionists nothing more than the psychological feelings of approval and disapproval which are the results of moral conditioning. However, whatever the status of these "moral sensations" are, it does not matter to the argument I wish to present.
So let is be granted that these intuitions are genuine in the sense that those whom claim to have them are honest about their alleged ability to perceive such non-natural properties as "goodness" and "evil". Where does this leave us? Well, says the intuitionist, by virtue of the fact that these qualities are perceived they must, therefore, exist inherently in specific objects and actions. Moreover, because he or she can perceive these intrinsic qualities, he or she can directly know whether a certain action or behavior is good or bad or whether or not a certain object is beautiful or ugly. This is the foundation of intuitionist ethics.
The difficulty with the intuitionist's thesis is not that it is unverifiable or that there exists no good grounds to take them at their word, but rather that it is logically impossible for such an act to occur. Intuitionist ethics is founded upon a logical howler of confounding descriptive terms with normative terms. The intuitionist asserts that given any action A there is a corresponding effect or "moral sensation" x such that x determines the "goodness" of A. For example, let us say I witness Mr. So-and-so steal some money from a charity jar; with my perceiving this act there will be a cotemporaneous "moral sensation" of "evil" or "wickedness"; therefore, the act of stealing from the charity jar is "evil".
The logical blunder resides in the leap from perceiving the so-called quality of "goodness" to then ascribing the predicate of "goodness" to the act or object itself. When one asserts that an action A has the non-natural and intuitive property of "good", all one is doing is describing A and a description carries no prescriptive or moral force. If a given action does, in fact, cause the dubious non-natural quality of "goodness" of be apprehended by the intuitionist, this does not at all speak of anything ethically, only metaphysically and logically. It is akin to saying "x is blue"; for all one is really saying is that "A is accompanied by a certain feeling of such-and-such which I call 'goodness'". To put it as formally as possible, fx, where f is the descriptive property of "causes the moral sensation of 'goodness'", cannot logically entail that the proposition "x is good".
The reason for the impossibility of jumping from "A causes the moral sensation of 'goodness'" to "A is good" is that the former is a descriptive proposition, whereas the latter is a normative proposition. Normative propositions are used to convey the command or suggestion to preform a certain task or behavior; they are, to put it plainly, ethical propositions. To say that "x is good" is to say, normatively, that x ought to be desired and preferred over other possibilities. It says absolutely nothing of x itself. There is nothing factual about x which is gained or lost by attributing a normative predicate to it. Just as the act of Brutus killing Caesar can be described in a class of descriptive propositions, to say of the act that it was either justified or unjustified says nothing of the act itself, the factual series of events would be left untouched.
There is, in short, no logical justification to conclude from the fact that A has a certain property x that A is y, where y is a normative predicate. To say that A has the property x is to employ a descriptive term which carries no moral force; on the other hand, to say that A is "good" is to say nothing inherently descriptive of A and, therefore, one cannot say that this notion of "goodness" was perceived from A. In conclusion it is evident that the intuitionist is barred logically from speaking meaningfully of perceiving such non-natural qualities as "goodness", "evil", "beauty", and so forth.