Philosophy Versus Science

[Sheldon]

I am skeptical that any standardized test can assign a number score to a person's intellectual humility or open-mindedness. These are things (as Aristotle points out) that are developed over a lifetime, and manifest themselves in ways that are individual and unpredictable.

To be clear, the researchers of this study didn't just rely on standardized tests assessing various forms of reasoning abilities, but also on two scales for measuring intellectual dispositions/virtues. Even if these scales may not be the best measures of what they were designed to capture, the researchers had limited options and could only go with what scales had been used among the sample of interest.

That said, you may still be right to be skeptical here. However, in such fields as experimental psychology, it is assumed that these (and other psychological constructs) can be somewhat captured by scales, provided these scales have been tested properly and shown to be both reliable and valid. As for predicting future states/outcomes, some of these measures may also be backed up by studies demonstrating their predictive powers.

And honestly, we do have pretty good measures for such things as open-mindedness anyway. In fact, open-mindedness is one of the five main factors in the OCEAN model of measuring personality.

I would certainly hope that reading good books would help a person become aware of these virtues, and help think about how we can live them in the real world. This seems to work for some people, and not for others.

 It should come as no surprise then that majoring in philosophy helps boost one's logical and verbal reasoning AND various intellectual virtues.

"William Lane Craig holds a PhD in Philosophy from the University of Birmingham in England"

Citation

I've read his contemporary take on KCA, it would seem to be at odds with that assertion, unless you missed out a qualifying remark, for example "can sometimes help boost one's logical reasoning". It doesn't seem to have helped Craig's. His argument involves question begging and special pleading fallacies, and he has used argumentum ad ignorantiam fallacies in his apologetics. 

"Professor Craig claims that even if all the other arguments for God's existence were shown to be worthless, that would have absolutely zero impact on his belief that God exists. That's because his own religious experience tells him that he knows God exists, independently of any argument or evidence."

And rules out identical claims from other religions of course, special pleading...