Editing Is–ought problem (section)

===Indefinables===

Indefinables are concepts so global that they cannot be defined; rather, in a sense, they themselves, and the objects to which they refer, define our reality and our ideas. Their meanings cannot be stated in a true definition, but their meanings can be referred to instead by being placed with their incomplete definitions in [[self-evident]] statements, the truth of which can be tested by whether or not it is impossible to think the opposite without a contradiction. Thus, the truth of indefinable concepts and propositions using them is entirely a matter of logic.

An example of the above is that of the concepts "finite parts" and "wholes"; they cannot be defined without reference to each other and thus with some amount of circularity, but we can make the self-evident statement that "the whole is greater than any of its parts", and thus establish a meaning particular to the two concepts.

These two notions being granted, it can be said that statements of "ought" are measured by their ''prescriptive'' truth, just as statements of "is" are measured by their ''descriptive'' truth; and the descriptive truth of an "is" judgment is defined by its correspondence to reality (actual or in the mind), while the prescriptive truth of an "ought" judgment is defined according to a more limited scope—its correspondence to right desire (conceivable in the mind and able to be found in the rational appetite, but not in the more "actual" reality of things independent of the mind or rational appetite).<ref name="prescriptive truths">see {{cite wikisource |last1=Aristotle |first1= |author-link1=Aristotle |translator-last=Chase |translator-first=D. P. |translator-link=Drummond Percy Chase |anchor=II |title= |trans-title= |plaintitle=[[Nicomachean Ethics]] |wslink=Nicomachean Ethics (Chase) |edition= |series= |volume= |date= |year= |orig-date= |publisher=[[J.M. Dent & Sons]] |location= |language= |wslanguage= |isbn= |oclc=1085665737 |doi= |id= |page= |pages= |at=6.2 |wspage= |chapter=Book Six |wsat=II |plainchapter= |publication-date=1911}}</ref>

To some, this may immediately suggest the question: "How can we know what is a right desire if it is already admitted that it is not based on the more actual reality of things independent of the mind?" The beginning of the answer is found when we consider that the concepts "good", "bad", "right" and "wrong" are indefinables. Thus, right desire cannot be defined properly, but a way to refer to its meaning ''may'' be found through a self-evident prescriptive truth.<ref name="definables">As an example of philosophical argumentation that identifies particular indefinables, we take "being" and then "good". Aristotle stated that although being is not a genus (''Posterior Analytics'' 2.7), yet of everything that is, being is predicated (''Topics'' 4.1), and that the [[Genus-differentia definition]]s, of which he was the first recorded proponent, requires that its subject be defined through its genus and a differentia. But since nothing lies outside of what is predicated of being, there is nothing which can serve as a differentia. So being is postulated to be indefinable. Later, Aquinas made an [[argument]] that stated, "Good and being are really the same, and differ only according to reason.... [G]ood presents the aspect of desirableness, which being does not present." (''Summa Theologica'', Part I, Q. 5, Art. 1) So good is postulated to be indefinable.</ref>

That self-evident truth which the moral cognitivist claims to exist upon which all other prescriptive truths are ultimately based is: ''One ought to desire what is really good for one and nothing else.'' The terms "real good" and "right desire" cannot be defined apart from each other, and thus their definitions would contain some degree of circularity, but the stated self-evident truth indicates a meaning particular to the ideas sought to be understood, and it is (the moral cognitivist might claim) impossible to think the opposite without a contradiction. Thus combined with other descriptive truths of what is good (goods in particular considered in terms of whether they suit a particular end and the limits to the possession of such particular goods being compatible with the general end of the possession of the total of all real goods throughout a whole life), a valid body of knowledge of right desire is generated.<ref name="self-evident">See for example {{Cite book |last=Ruggiero |first=Vincent R. |title=Thinking Critically About Ethical Issues |publisher=[[McGraw Hill Education|McGraw Hill]] |year=2001 |isbn=9780767415828 |edition=5th |chapter=Chapter 6}}</ref>