Evaluation of Example 3: Osteoarthritis and Joint Pain

Passage:

”The symptoms of joint pain, however, correlate poorly with X-ray evidence of OA [Osteoarthritis]. The reason behind this remains unclear, but it is likely that the pathological changes associated with joint OA and the symptoms of joint pain are not always visible on radiological imaging. The prevalence of joint pain is therefore likely to be far higher than the prevalence of radiographic evidence of OA.“

Chin Teck Ng and Maw Pin Tan, “Osteoarthritis and Falls in the Older Person,” Age and Ageing 42 no. 5 (Sept. 2013), 562.

Analsyis:

No fallacy present. Although, at first glance, the the conclusion might seem to be contained in a premise, the conclusion is the result of a deductive inference. The premises' subjects include the evidence and pain of joint osteoarthritis and the conclusion's subject is just the pain of joint osteoarthritis. The two-step argument in question can be translated as follows:

Osteoarthritis joint changes are not always evident on X-rays.
Thus, joint pain is likely to be more than X-ray evidence shows.
Therefore, joint pain correlates poorly with X-ray evidence..