Rationality means making logical choices that will lead to ends that correspond to your desires and values. It says nothing about the validity of those desires or values.
Can we evaluate desires or values as being rational? As others have said, we can rationalize any desire or value -- you can't derive most of them from logical principles.
Can we evaluate desires or values as being rational? As others have said, we can rationalize any desire or value -- you can't derive most of them from logical principles.