What you have to understand is that studies in specificity tend to deal with training transfer to sport. I hate to be the bearer of bad news but nobody much cares how your Romanian deadlifts transfer to your squats. Nobody sporting a lab coat anyway.
Wow, that is news to me, it's funny how some Guru's will tell you to do this, this & this & your lift of choice will go up. In fact, "we've" been told that as well at our gym.
Hume was writing about moral ethics but in purely scientific terms we see this error all the time and it is a big problem in studies of specificity since we are "observing" what happens and then wondering if it "ought" to result in a certain performance improvement or transfer.
I never realized how tricky specificity is. I guess I should have been listening more closely, there is a huge difference between "ought" & "is".
The average trainer, coach, or fitness guru is no more qualified to design an effective and legitimate study into specificity (or anything) than I am to recreate a Jackson Pollack. No matter how drunk I get.
Shhh….my common sense is tingling.