I’m not a very good logician and, at best, a mediocre philosopher of science, even though I love the latter (but hate the former); so, I could use some help figuring this out. Thanks.
I believe nightshades (tomatoes, potatoes, chili peppers, eggplant, tobacco) give me migraines.
Out of modus ponens, modus tollens, affirming the consequent and denying the antecedent, it makes the most sense to me in terms of modus ponens, and even more in terms of denying the antecedent. But philosophers of science, as far as I know, don’t talk much about modus ponens, do they?
Modus ponens is both inferentially valid and makes sense to me:
If P, then Q.
P.
Therefore, Q.
If I eat nightshades (P), then I get migraines (Q).
I eat nightshades (P).
Therefore, I get migraines (Q).
But denying the antecedent, though inferentially invalid, makes even more sense to me, and conforms most to my experience:
If P, then Q.
Not P.
Therefore, not Q.
If I eat nightshades (P), then I get migraines (Q).
I do not eat nightshades (not P).
Therefore, I do not get migraines.)
Modus tollens seems even worse to me:
If P, then Q.
Not Q.
Therefore, not P
If I eat nightshades (P), then I get migraines (Q).
I did not get a migraine (not Q).
Therefore, I did not eat nightshades (not P).
But Popper used modus tollens to reject the hypothetico-deductive model and get out of the inductivist dilemma, which utilizes the inferentially invalid “form” of affirming the consequent:
If P, then Q.
Q.
Therefore, P.
To my nightshade example, this is the worst choice to me because it’s invalid and contrary to my experience:
If I eat nightshades (P), then I get migraines (Q).
I get migraines (Q).
Therefore, I eat nightshades.
This is a common problem for most people trying to figure out causes and effects in terms of consumption choices.
So, is modus ponens the best logical form for my experiment (does it even qualify as a scientific experiment or is it too “anecdotal”?)? And how do I best relate this to Hume’s views on induction and cause and effect, especially in terms of my experience? It seems like a simple problem (Popper), or puzzle (Kuhn). I hate migraines. If nightshades cause me migraines, then I’ll quit them. My test (although probably not severe enough by Popper’s terms) was the elimination diet method, where you quit food X for a month (or more, in my case it was about three), then eat a bunch of it/them for a few days (I used to get a lot of migraines until I started eliminating things from my diet, and it bears future practice because I’ve eliminated other things in relation to migraines and other symptom–there might be another problem with this method because it might not account for tolerance phenomena, e.g., it might be that if you eat nightshades or food X frequently, then your body adjusts; that is, elimination dieting doesn’t control for metabolic adaptation confounds).
Also, it seems to me that the way I phrase it could make a difference, but I can’t think of a way to phrase it to fit modus tollens (and therefore falsifiable) or affirming the consequent (and therefore hypothetico-deductive).