A second advantage of the approach is that it is largely confined to observable empirical phenomena.
All four of these criteria are observable and well-evidenced phenomena.
Desire, like knowledge, is, of course, in one sense an observable phenomenon.
These things and others like them are observable phenomena distinguishing a hungry animal from one which is not hungry.
This approach is nevertheless valuable because it can deal well with some macroscopically observable phenomena.
And it is also at odds with easily observable phenomena in contemporary China.
It is a phenomenon observable three days out of five in the planet of love.
There are many observable physical phenomena that arise in interactions involving virtual particles.
Only through the mediation of value can economic theory really explain the observable economic phenomena.
Any "theory of everything" is similarly expected to be based on axioms and to deduce all observable phenomena from them.