Pardon me, but depending on the question, both theories about whatever it is could very well be wrong, or both could be partially right. Life is very rarely so neat and clean as to present you with exactly two possible answers, one absolutely right, and the other absolutely wrong. ;)
I found that those of my friends who were admirers of Marx, Freud, and Adler, were impressed by a number of points common to these theories, and especially by their apparent explanatory power. These theories appear to be able to explain practically everything that happened within the fields to which they referred. The study of any of them seemed to have the effect of an intellectual conversion or revelation, open your eyes to a new truth hidden from those not yet initiated. Once your eyes were thus opened you saw confirmed instances everywhere: the world was full of verifications of the theory. Whatever happened always confirmed it. Thus its truth appeared manifest; and unbelievers were clearly people who did not want to see the manifest truth; who refuse to see it, either because it was against their class interest, or because of their repressions which were still "un-analyzed" and crying aloud for treatment.
The most characteristic element in this situation seemed to me the incessant stream of confirmations, of observations which "verified" the theories in question; and this point was constantly emphasize by their adherents. A Marxist could not open a newspaper without finding on every page confirming evidence for his interpretation of history; not only in the news, but also in its presentation — which revealed the class bias of the paper — and especially of course what the paper did not say. The Freudian analysts emphasized that their theories were constantly verified by their "clinical observations." …
These considerations led me in the winter of 1919-20 to conclusions which I may now reformulate as follows.
1. It is easy to obtain confirmations, or verifications, for nearly every theory — if we look for confirmations.
2. Confirmations should count only if they are the result of risky predictions; that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory — an event which would have refuted the theory.
3. Every "good" scientific theory is a prohibition: it forbids certain things to happen. The more a theory forbids, the better it is.
4. A theory which is not refutable by any conceivable event is non-scientific. Irrefutability is not a virtue of a theory (as people often think) but a vice.
5. Every genuine test of a theory is an attempt to falsify it, or to refute it. Testability is falsifiability; but there are degrees of testability: some theories are more testable, more exposed to refutation, than others; they take, as it were, greater risks.
6. Confirming evidence should not count except when it is the result of a genuine test of the theory; and this means that it can be presented as a serious but unsuccessful attempt to falsify the theory. (I now speak in such cases of "corroborating evidence.")
7. Some genuinely testable theories, when found to be false, are still upheld by their admirers — for example by introducing ad hoc some auxiliary assumption, or by reinterpreting the theory ad hoc in such a way that it escapes refutation. Such a procedure is always possible, but it rescues the theory from refutation only at the price of destroying, or at least lowering, its scientific status. (I later described such a rescuing operation as a "conventionalist twist" or a "conventionalist stratagem.")
One can sum up all this by saying that the criterion of the scientific status of a theory is its falsifiability, or refutability, or testability.
Pardon me, but depending on the question, both theories about whatever it is could very well be wrong, or both could be partially right. Life is very rarely so neat and clean as to present you with exactly two possible answers, one absolutely right, and the other absolutely wrong. ;)
At first, the quote did not seem to be logicly supportable and you pointed out the obvious flaw; and you could be correct.
On the other hand, that logic may not apply to the macro-evolution v. intelligent design/special creation debate. The positions are so diametrically opposed that it is impossible to reconcile, or synthesize these opposing positions into one conclusion without utterly refuting both sides. While man cannot fully comprehend the designer and his methods, one can still readily support the conclusion that there is a creator.
Also, since in this debate no one has prososed a scientific model other than macro-evolution or creation/intelligent design, it is logical to conclude in this case that one must be true and the other false. This being this situation we find ourselves in, if one of the positions can be demonstrated to be false based on science and the observable evidence, the opposite position must be true.
Can this be determined with absolute certainty. Probably not. Can it be determined to the point where one might risk his very life and soul on it? Absolutely, because I have done it!
Evolutionists are so eager to point out that those who believe in the God of the Bible base their belief in a Creator soley on faith unsupported by evidence, yet those same evolutionists base their faith in evolution on mere speculation and suppositions which they claim to be facts. Merely stating that macro-evolution is a fact just because one makes the claim is no different than claiming that black is white. The truth stands on its own, and does not change merely on the whim of a man.