modus ponens, denying the antecedent, migraine cause

Seems to me, landis, like you’re going about this all wrong–I think this abstract contemplation on the logic of your experimentations is a red herring; keep it simple–the way you described your plan for experimentation would do just fine:

But since this is a philosophy forum, why don’t we address your concerns over the logic of this whole thing.

I had an interesting discussion about the logic of conditionals recently: viewtopic.php?f=1&t=185298.partial

Essentially, the only reason why the above is inferentially invalid is because eating nightshades may not be the only thing that gives you migraines. Hangovers might do it; getting bashed over the head with a baseball bat might do it.

The reason why denying the antecedent seems to work for you is that all this stuff is implicitly assumed–you’re not just thinking that abstaining from nightshades will eliminate your migraines but also abstaining from a night of heavy drinking, or getting bashed over the head by a baseball bat, plus anything else that might give you migraines.

Yeah, what’s wrong with that?

Is this what Popper did? I don’t get it.

Right, which is another way of explaining why your example above about denying the antecedent seems to work for you: just because you get migraines doesn’t mean you must be eating nightshades–as I said above, your migraines could come from a whole swack of different things.

I think you’re getting ahead of yourself here. Let’s not assume tolerance comes into play at first. If you find that abstaining from nightshades eliminates your migraines, problem solved. If not, then try the test again controlling for tolerance.

Modus Tollens wouldn’t falsify anything.

If I drink poison, then I’ll die.
I’m not dying.
Therefore, I didn’t drink poison.

This does not falsify the claim that drinking poison causes death.

I don’t think there’s any logical way of putting it in terms of affirming the consequent. Like I said, affirming the consequent only seems to work because you’re bringing in a bunch of implicit assumptions.

He might get migraines from something else. P is not saying that the only way he gets migraines is from eating nightshades, so the conclusion is false in general, though it might be right in his case.

But the minor premise is saying he didn’t get a migraine.

The conclusion is that he did not eat nightshades. If eating nightshades is supposed to give him headaches and he doesn’t have a headache, then he must have not eaten nightshades.

Now, I realize that logic paints things in a very black and white manner, and I don’t think real life works that way. Therefore, I can see how the conclusion drawn above may, in some cases, be false. When he says “If I eat nightshades, then I get migraines,” he might mean nightshades usually give him migraines or that 99% of the time they do, or perhaps on occasion nightshades give him minor headaches which he doesn’t consider strong enough to be migraines. If that’s the case, then sure it’s possible for him to eat nightshades and not get migraines, but he certainly said, in the minor premise, that he didn’t get a migraine.

Oops. Man, did I not read that well.

He has to realize that what he also did besides eating them might have canceled the effect they normally give. So even if he eats them and doesn’t get a headache, he still doesn’t have enough information to be conclusive with simple logic. Eating beans with rice makes a serious difference from eating beans alone. The rice completes a protein in the intestines which prevents gas production as well as reducing radicals that get in the blood of many people, but not everyone.

There are very many variables unaccounted for with such experiments making isolation of cause difficult to determine with certainty.

:laughing: Happens to the best of us, I guess.

It’s funny how even the silly mistakes we make can lead into good discussion and new insights.

So like eating nightshades while popping a few pills of Tylenol? Sure, that could happen. But I think you can still do a thorough scientific investigation and get reliable results at the end of the day (although that might be a hell of long day).

landis seems to be saying that he gets migraines. He suspects that nightshades might be the culprit. There is a very simple test to see if there is a connection: go a few months without nightshades and see if the migraines disappear. If there is a confounding variable that happens to come up during these few months that might be having the effect of cancelling his migraines (ex. he, for some bizarre reason, decided to start a habit of popping T3s every morning at around the same time the experiment started–and this by sheer coincidence, landis not making the connection between that and the onset of the two months of his experiment), then we’ll find out as soon as that confounding variable disappears. Once it does, and his migraines come back, then he’ll know that a nightshade free diet does not cure his migraines and he’ll know to look for another cause. But if the confounding variable doesn’t ever disappear, well, what’s the problem? He may be wrong to conclude that his migraines are caused by the nightshades, but he’s free of migraines. So problem solved anyway.

Holy crap. I posted this question on another philosophy forum and it got all heated instead of actually constructive like this. Thanks a lot contributors. This is sweet. I’m going to give the thread a read through or two then I’ll get back to you all. Thanks again.

Exactly. As gib put it:

Yes, I was going about it wrong. And I wasn’t just testing nightshades and migraines but the utility of Popperism for problems like this, which, as you rightly point out, overcomplicates matters.

True. But I have enough data to satisfy my suspicions.

Bingo! Well put, gib. This is exactly what I did. I’ve done it with dairy and wheat for similar and varying symptoms. I’m reminded of Hume’s A Treatise of Human Nature, Section XII, “Of the Probability of Causes,” where he says:

And reflecting on the rest of his most subtle philosophy in light of my consumption woes, it’s helpful to use his scepticism to guide me in being satisfied with approximating a causal analsyis without controlling for all confounds, which is impossible. No?

There’s a significant difference between “if” and “if and only if”, or “iff” as it’s also known. The step of denying the antecedent works only for iff P then Q.

“If I guess the right number in roulette, I win big at the casino” may be true, but you can still win big in other ways at the casino. “Iff I guess the right number in roulette, I win big at the casino” is only true for casinos that restrict their scope to roulette.

However, if eating nightshades (among other things) always give you migraines, it’s fair to say that if you don’t have a migraine, you haven’t eaten nightshades (recently). So modus tollens is good there.

Wanting to find out whether nightshades cause it, in a complex multivariable situation like normal life, is a matter of statistics rather than logic. However, if you’ve ever eaten nightshades and not had a migraine soon after, you know that they don’t all always cause migraines.

This is a false dichotomy as statistics is a form of inductive logic.

deleted (accidental replication)

Land is, how have you been medicating? I have had similar, and addicted to all kinds of drugs, which over a period of time can prove dangerous or even lethal.

Then I discovered natural mess, thank god, they did make a huge difference.

Try Tumeric, fresh juiced with red grapes, with ginger, every day. In addition Tumeric tabs, 750 mg twice a day. Gave me almost total relief in two weeks , and as I am still new to the regimen, it may be still premature to say it a complete remission, (for I have had intolerable pain for the last 25 years), but so far so good. Will let you know with my success with it after I pass the thirty day mark.

This thread is hilarious. The OP, landis, speaks in latin in attempt to obfuscate and complexify the sister of 2+2=4 in a fantastic manner.

Jerkee comes to the rescue, with down to earth english and a list of herbal remedies.

Look, my answer to landis is this.
If you want to learn the truth of tomatoes…
Do the science, learn the scientific method, try learning how to program computer programs. Look less to latin and scholastic esotericism as your answer, and turn more to doing science and programming

Not learning a bunch of latin to answer the equivalent of 2+2=4 type questions.

Could be a variety of things. Could be pesticides. You need a lab. And you need men in your lab. Women too. And you need to make sure your tomatoes are GMO free.

GMO’s have tainted the ability of science to objectively test fruit and vegetables. The sample set has been polluted. It can never recover.

Whhhhhaaaat? I was trying to help a pain sufferer, and others’s advice is well suited, for migraine try not analyze, that may exerbitate the pain, rather, try something natural, earth giving. It takes migraine sufferers to know how devastating that is.

Let me ask this, Ha Ha, have you ever have had migraine? It can be devastating to the point, you can’t move.

I may be making a service to her, as one human being to another. Remedies to pain transcend any philosophy, if they work.

In my firm doctoral opinion, Landis’ original post in itself causes a migraine.

???
… Ummm… :confused:

Well, fasting off everything besides nightshades will most certainly give you a migraine as the body dumps toxins…

As James noted, you need extreme conditions to isolate food variables…

To add to that, those extreme conditions can be indiscernable from what you are trying to figure out!

A catch 22

Turmeric is great advice - one of the best edible anti-inflammatories…

It’s even good at preventing cancer

A study recently came out that inflammation is the highest known precursor to cancer

That’s cute only humean…

“If” implies “only if”…

There’s not really a logical distinction

It’s like saying “the” and “only the”

They both mean the same thing