- Affirming the Consequent is a logical fallacy that takes a known true statement [if P then Q] and invalidly concludes its converse [if Q then P]:
- If Bill Gates owns Fort Knox, then Bill Gates is rich. Bill Gates is rich. Therefore, Bill Gates owns Fort Knox. False!
- If an animal is a dog, then it has four legs. My cat has four legs. Therefore, my cat is a dog. False!
- If it’s raining, then the streets are wet. The streets are wet. Therefore it’s raining. False! It could be raining or it could be something else. The “therefore” claim is false.
- How does ‘Affirming the consequent’ apply to evolution? We have not observed “evolution”. No one has, and no one will, despite the effort (see LTEE). What was observed is Resemblance, the Birth Mechanism, Variability and Adaptability. Neither of these (even combined) can logically be extrapolated to “evolution”, namely the hypothesized transmutation of one type of organism into another. Proofs of “evolution” always take the form: If “evolution” is true, then XYZ is true. XYZ is true. Therefore “evolution” is true. This is a classical Affirming the Consequent logical fallacy.
- Let’s see some concrete examples of “proof of evolution” fallacies:
- If “evolution” is true, some fossils are ancestors of and therefore resemble existing organisms. Fossils resemble one another and existing organisms. Therefore “evolution” is true. This argument fails because there will always be some resemblance between two or more entities (even chairs and cats have four legs in general). Also, a fossil can always be from an unrelated branch of the “tree of life” which circularly presupposes “evolution” anyway.
- If “evolution” is true, organisms are genetically similar. Organisms are genetically similar. Therefore “evolution” is true. This argument is false because other hypotheses such as common design account for genetic similarities just as well.
- If “evolution” is true, one might expect common embryology. Similar organisms have similar embryology. Therefore “evolution” is true. This fails because embryology is expected to match genetics and morphology, hence the previous counterargument applies.
- If “evolution” is true, one might expect vestigial organs. What looks like vestigial organs can be observed. Therefore “evolution” is true. This fails because what if those organs are useful rather that “vestigial”? And why would “evolution” not do away with “vestigial” organs as soon as they become useless? In sum, why can’t these organs have another reason or origin than “evolution”?
- If “evolution” is true, one expects adaptability such as antibiotic resistance. Antibiotic resistance is observed. Therefore “evolution” is true. This fails because adaptabilities such as antibiotic resistance are compatible with other hypotheses, not just “evolution”. In addition, antibiotic resistance is ubiquitous, limited, reversible, and never observed to result in organism transmutation aka “evolution”.
- How can “proofs of evolution” avoid the ‘Affirming the Consequent’ logical fallacy? Direct confirmation of “evolution” is unlikely as shown by the LTEE study. Alternatively, an observation that is true for “evolution” and only for “evolution” might also work. In other words, what’s missing from all the examples above is a true statement of the kind: “only if evolution is true, then XYZ”. Of course, excluding all alternatives to “evolution” is an impossible task therefore, given that Intelligent Design is the main rival, proponents of “evolution” need only add a true statement of the kind: “if Intelligent Design is true, then XYZ is not true” to turn their invalid arguments into valid ones. But even this lower bar cannot be met by “evolution” proponents, thus making all “proofs of evolution” invalid.
- Isn’t then all science ‘Affirming the Consequent’? For example, “if Newtonian physics is true, a ball thrown at angle Theta and speed V will land D meters away. The experiment is carried out, and we find that the ball landed distance D away. Therefor physics is true.” No! This is not a fallacy because it meets the “if and only if” requirement and is limited to “everything else equal” cases. Rockets do not disprove this claim because everything else is not equal between them and thrown inactive projectiles. In addition, no one claims a single experiment confirms all Newtonian Mechanics the way “proofs of evolution” are presented. In this case, multiple combinations of Angles and Speed result in the same Distance without violating Newtonian Mechanics because this experiment proves only portions of the theory.
Links:
https://en.wikipedia.org/wiki/Affirming_the_consequent
https://www.amazon.com/Biblical-Wisdom-Literature-Joseph-Koterski/dp/1598035258
phoodoo,
As I said, modal logic is beyond your capabilities:
Try following the instructions. Pretend you’re a grownup, if that helps.
keiths,
I just did, now are you going to explain how definitely doesn’t get changed to maybe?
phoodoo,
No, you didn’t. You tried to do modal logic and you got in over your head.
Again:
Are you able to follow simple instructions, or am I asking too much of you?
keiths,
You refuse to even explain your rules for negating, so how can I follow some arbitrary rules of yours?
You and Jock have both claimed that might gets negated into definitely.
So obviously definitely has to get negated into might.
So every time you say This then that (definitely must be assumed, so we must negate into might).
Your fucked up rules have bitten you and Jock in the ass, and now you are trying to ignore it.
You know they did not invent logic right? Those “fucked up rules” are not something they are making up.
You know that you can go and learn it and then show them how it’s done? Shame them! Become an expert in it then show them where they’ve done it wrong!
What, the arbitrary rules he’s just explained?
Once the rule for negating is explained (hey, why do you need it explained anyway you are expert at all this already right?) you’ll have another go?
OMagain,
I already did dufus:
I negated rain, I negated me, I negated won’t and I negated out. Both Keiths didn’t seem to like those results. Maybe there are more things I need to negate?
I will be waiting for Jock and keiths to explain why definitives don’t get negated to maybes. I get the feeling they are going to dodge that one. Call me a soothsayer.
You make that future happen yourself. It’s almost as if you don’t have free will.
With this sort of problem you can easily find a reference in the available literature that demonstrates why they are wrong and you are right. There are any number of references available for even a casual search.
Why not shown them to be the fools that you think they are?
And here we see the difference between you and, well, almost everybody else here.
Almost everybody here is happy to answer questions. Jock and Keiths will no doubt explain what you want explained. And they’ll answer your questions along the way.
And yet you refuse to do the same. How do you think that makes you look? How strong do you think that makes your position look to the casual observer? It simply illustrates your double standard, you expect your questions to be answered to arbitrary levels of detail but don’t return the favour.
Your crime is also your punishment however.
Just as walto thinks I’m silly to try to explain propositional logic to phoodoo, I have to admire keiths’s bravery in sallying into modal logic with him. There’s not a cat in hell’s chance he’s gonna get that…
So phoodoo, in propositional logic, statements are either true or false.
The negation of a statement is a related statement that has the following properties:
If the statement (P) is true, then its negation (not-P) is false.
If the statement (P) is false, then its negation (not-P) is true.
Notice that (P and not-P) is false, and (P or not-P) is true, for ALL P.
You appeared to understand this with your
which is a fallacy.
You correctly negated both terms of the opening conditional
But then failed to follow the instructions and decided to also negate P2 and C.
Strange that you had no trouble whatsoever negating statements until you realized you were WRONG. So you headed off into modal logic.
As I noted:
Another possibility is that phoodoo understands it all quite well and is just playing games — leading you all along.
phoodoo,
Maybe you need to follow the simple instructions:
Neil,
Phoodoo has backed himself into a corner and is looking for a way — any way — to save face.
Some people say the same thing about Trump: “We’re playing checkers. He’s playing 3D Chess!” But, ah, no. Phoodoo just doesn’t understand this stuff.
Helpful Hint: don’t try to negate things (or you). Just stick a “not” in front of the statement you’re supposed to be negating.
If phoodoo were playing 3D chess, he would never have condescended to negate an unambiguous statement; he would have stuck rigorously to his ‘ambiguity’ defense.
Wandering, for whatever reason, into propositional logic is a strategic error.
And yet you have claimed ambiguous statements are no problem for valid arguments! Don’t pretend you forgot already???
Ambiguous not a problem?
My prediction is coming true, you and Keiths are trying to dodge answering why “might not” should be negated into “definitely will”, but “definitely” will is not negated into “might not.”
Phoodoo the soothsayer.
Who are you telling not to negate things? The guys with the rules they can’t abide by for more than one sentence? You see their problem, don’t you Walto?
See why they are not answering?
Might =definitely won’t
But
Definitely won’t { /=/ } might
Even someone playing checkers can see this problem Walto.
What happened to your trap Doc, your tongue got stuck in it?
phoodoo,
For propositional logic, validity is on page one. For modal logic, the negations of modal statements, maybe page 3.
You just prefer to fight though. Right or (as in this case) wrong. So stubborn and bellicose.
I have no recollection of making such a claim — perhaps you misunderstood. Provide the link, and we can collectively figure this out…
walto,
Are those the same pages where you say who your helpful hint for negating was for?
Seriously?!?
Not how it works. If you negate, you MUST apply that transformation everywhere:
If not P then not Q.
not Q.
Therefore, not P
Still a fallacy.
You can’t do that! You can’t leave the rest unchanged. That is not a transformation and not a fix. It is something entirely different.
And the other possibility is that DNA_Jock just can’t fix stupid, aka “affirming the consequent”. He would be better off trying to get lead into gold or a perpetual motion machine.
Exactly!
Nonlin.org,
Yes. And not only that, Jock (and keiths) don’t seem to realize that if you are going to allow transforming SOME parts of a premise, arbitrarily, deciding which parts you will negate, which parts you won’t negate, for no reason other than you think you can, and claim this says something about the original argument, is ludicrous.
You can change black to white, me to you, was to is going to, high to low, fat to thin, on and on…
Arguing that changing might do something, negates to 100 percent won’t do something , what nonsense. That’s why I used that example. Premises can be extremely complicated, they don’t have to be the one sentence simple affairs, so this idea that you can start rearranging their meanings completely, and say something coherent, fraid not.
It has nothing to do with it being a modal argument Walto.
That’s right!
It is a new, different argument. Specifically, it converts any example of Affirming the Consequent into an example of Modus Tollens.
“Fixing” its validity, as it were.
Do you agree?
[If you take any propositional argument and negate ALL of the terms, you will produce a different argument, but one that has the same validity/invalidity as the original argument. Another short road trip looms.]
What? Is this a commandment logicians hadn’t been informed of?
Roughly, yes.
Nonlin.org,
Of course it’s different. If one is valid and the other invalid, it’s got to be a different form of argument, no? There’ not trying to make the same argument look different, they’re (pointlessly) trying to explain to you what the hell is going on
Oh ffs. What a waste of life this thread is.
Let them lie in their squalor. They have no interest in understanding anything.
If only FMM was here to remind phoodoo that God is the Logos = Logic, and therefore he needs to stop fighting against logic… oh boy, I miss that presuppositionalist intellectual powerhouse 😞
phoodoo, listen. We’re talking about propositional logic. In that, you can represent the premises and conclusions with letters. Each letter stands for a proposition, whatever it is–true, false, complicated, ambiguous, dumb, etc. They may contain modal terms or they may not. You may know whether they’re true or you may not. You may think one is true even though it isn’t. NONE OF THAT MATTERS. It’s just Ps and Qs.
P THEN Q
P
THEREFORE, Q
is a valid form of argument (called modus ponens)
P THEN Q
Q
THEREFORE, P
is an invalid form (called affirming the consequent)
P THEN Q
NOT-Q
THEREFORE, P
is a valid form (called modus tollens)
When is a form valid? When, if we assume the all the premises are true (whether they are or not), the conclusion must be true.
When is a form invalid? When it’s possible for all the premises to be true (whether they are or not) and the conclusion could still be false.
You can show which forms are valid using something called truth tables: they have a column for each contained proposition and a row for T and F. You put in all the possibilities. If there’s a single row in which all the premises are true and the conclusion false–WHAM! invalid form. Nothing could be simpler: any 15-old could master it. But….you have to actually want to understand what you’re talking about and not insist on fighting over every fucking thing for no reason.
Now, logic gets much more complicated than this, when we move away from propositional logic–which takes the whole statements as units, and dig inside each sentence. Then, we may have to look at quantification terms (“every” “any” “some” all “none” etc.) or we may have to look at modal terms (“might” “possible” “necessary” “impossible” etc.
But propositional logic (where affirming the consequent, which this OP is supposed to be about comes from), is dead easy. And yet you and your buddy here just keep talking shit.
walto,
This entire spiel has vitually nothing to do with my objections (nor nonlins).
Here, so if you can figure out why this from Jock is wrong:
Spot it?
And you still haven’t taken a stab at why “might go”, negates to definitely won’t go, but “definitely won’t go” doesn’t negate to “might go?”
Tough one, yea?
P THEN Q
NOT-Q
THEREFORE, P
??
Therefore, not P. Everybody makes mistakes, even not me 😂
Sorry, left the tilde out there. Thanks for noticing!
No. not tough at all. Jock is not wrong there.
The sort of pathetic thing here is that nothing about anything I or Jock has written in this thread has anything to do with whether evolution is right or there is a God or ID is true or false or a single thing that it’s so important to nonlin and you to advocate about at this site. We are simply pointing out stuff that’s on the first page or two of every survey of syllogistic logic since Aristotle.
You’re fighting as if something important hinged on this. But all you keep doing is showing that you don’t understand what validity and propositional logic are. If I didn’t like you, I’d use the ignore function because I don’t like seeing you do this kind of thing. Nonlin, who is obviously just a prick, keeps me from the ignore function because I’m kind of enjoying seeing him embarrass himself (again, to no purpose whatever), in every comment he makes.
walto,
So you can’t see the mistake? I will be happy to point it out to you later.
Still dodging the “might becomes definitely, defintely doesn’t become might problem, I see. Can’t say I blame you. I predicted Jocks and Keith would dodge, I forgot to include you.
And Doc is wrong. And so are you.
Surprised you didn’t call it fake logic. No collusion.
I had not seen that construct before. It took a while for me to figure it out. I still have to visualize truth tables. I would never phrase an argument that way.
Being undeniable is not the same as being lucid.
walto,
Indeed …
Not that it matters to you, but you’re getting the modal terms as balled up as you have validity. You mix up various types of necessity here. “Definitely” as you’re using it doesn’t mean the same thing as “necessarily.”
“This might happen” means “It’s not impossible that this happens” or “There is a possible world in which this happens.” It doesn’t have anything to do with what people know or what’s consistent with what they know. “Necessarily, this will happen” means there are no possible worlds in which this doesn’t happen.
“This will definitely happen” as you’re using it means, roughly, I’m sure that this will happen. That’s an epistemic matter. Epistemic modality consists of what is consistent or inconsistent with what somebody (or everybody) knows. The logic there is a bit different, but even if it were identical you can’t just mix the two kinds.
So, there again you’re making things complicated that are quite simple: page 1 stuff.
Here’s a picture of the modal “square of opposition” that shows how negations of modal propositions work. As has been pointed out about fifty times, it’s entirely irrelevant to the fallacy of affirming the consequent. But I suppose you may as well know that you’re getting it wrong too.
https://plato.stanford.edu/entries/negation/figure2-square.png
That was a nice post setting up a great punch line.
I suspect it is unintended, but IMHO your recent posts have downplayed the belittling and emphasized the tutoring. KN would be proud!
The definition of definitely that I am using?? Have you been asleep for the first half of this thread and so you think it is me who introduced the term definitely?
No wonder you are so confused. It was Jock who introduced it, maybe you need to go back and read. I am telling you why his use of it is ridiculous, and now you are trying to tell me my use of it is wrong.
That’s pretty funny Walto. And you are going to try to insult me about not knowing what I am talking about? Save your breath.
And it has already been pointed out about fifty times, and agreed by pretty much everyone, that the arguments regarding evolution that Nonlin pointed out ARE fallacies of affirming the consequent, so who the heck knows what you are talking about.
The issue that was raised, was about how to validate those arguments so that they are not fallacies. So Jock starts making up new arguments and thinks he is saying something clever. Its apparently all gone over your head, or you are just too lazy to follow the thread.
Don’t blame me for your lethargy.
Flounce out time?
Maybe in your parallel universe where logic and reason don’t apply
I for one completely agree with Phoodoo’s assessment of breath management. for Walto,.
Although I suppose in might be that Walto is engaged in some kind of fitness regime or meditative practice.
BruceS,
Look at all the gas filled windbags who don’t even have the faintest idea what the conversation is about, but they have all these pumpkins they want to smash but they have no idea what to do with them.
What has your contribution been to this thread so far? Dazz’s? Omagain’s?
You all seem to think if you just slobber the first pejorative you can think of you are actually saying something. Go slather in your own shit Bruce, along with Omagain and Dazz. Later you all can go to Chuck E. Cheese together