“The assumption upon which we have proceeded in our discussion is that whatever exists is real. Matter and its qualities, particulars and universals,we have argued, are real because they exist; and this obviously assumes that whatever exists is real. Now this assumption we all inevitably make. Tables, trees, mountains, human beings, the earth, the solar system- these exist, that is, they are real. Reality and existence, thus are, synonymous terms. Whatever can be said to exist must, for the reason, be granted reality.
To say that the real is whatever exists, however, does not get us anywhere in our definition of reality unless we can indicate the distinguishing marks of existence. We have only changed the form of our problem from, What is real? to, What can be said to exist? But the change in form is helpful. What exists? is a question more easily answered than, What is real? Now the only means by which we can determine what exists is that interpreting activity of the mind which we have called judgment and the basal characteristics of which we have noted in our discussion of it. Whatever judgment forces us to say exists does, we have to assume, necessarily exists. If my judgment, ‘This before me is a typewriter desk,’ is a necessary judgment, that is, if its assertion and acceptance involves less contradiction of other judgments than does its denial and rejection, then the typewriter desk exists and must be called real. Of couse, some judgments that at one time are supposed to be necessary judgments turn out later not to be necessary at all, and so we are not always sure of the existence of objects of judgment. But this means nothing more than that some of our judgments are erroneous.
But are not so called ‘appearances’ necessary judgments also, and must they not therefore be called real? When I see the stick bent in the water, for example, or the railway lines converging in the distance,are not the judgments, ‘The stick is bent’ and ‘The lines are convergent,’ necessary judgments? In a certain sense they undoubtedly are necessary. In respect to the laws of refraction of light in the one case, and of the laws of optics in the other, each judgment is a necessary judgment and is as valid and true as any other judgment could possibly be. When I say that because of the laws of refraction of light the stick in the water is bent, or because of the laws of optics the perspective of the railway lines is convergent, in each case my judgment is true and the object of judgment exists and is real; under these conditions the ‘bentness’ of the stick and the ‘convergence’ of the lines are real. If, however, I judge the stick is bent out of the water, or that the railway lines converge outside of the field of vision, then in each case the judgment is not a necessary judgment, is, in fact, erroneous, and the object of judgment does not exist but is only an ‘appearance.’
What, then, is the distinction between appearance and reality? If our analysis is correct, the reply must be: it is the distinction between erroneous judgments and true judgments. The objects of true judgments exist and are real; the objects of erroneous judgments do not exist and have appearance only.”
(Cunningham, Problems of Philosophy, 188-89)