- 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
Wah wah, someone said something nasty so I’m going to use that as an excuse for my flouce out.
Wah wah.
Snowflake.
So, will you be continuing the conversation now you seem to be aware that you are in error? Or is this how you deal with that?
Simply click “ignore” and carry your conversation on. Go on, do it. I promise it won’t make any difference to me. We have a very one way conversation, you not knowing what I’m saying won’t actually make any difference.
My contribution has been to laugh as you get taught what you were already pretending to know. Mockery is my contribution. If your skin is too thin, perhaps you should cut down the mockery yourself.
OMagain,
If you haven’t noticed by now, you never get under my skin, because I never respond to you. I find you to be the single dumbest poster here ever frankly. You should be angry at Richard Hughes for handing that mantle off to you.
I have never seen you write even one interesting, insightful or even slightly entertaining post in all the years you have posted here. Its almost remarkable endurance how you can manage to never ever say anything even touching the fringes of thoughtful prose.
Its is virtually impossible for you to get under my skin. It would be like me getting upset at a homeless beggar trying to clean my windscreen, but tripping over the curb and spilling the bucket over their head, long before they even got to my car. I would barely notice other than to shake my head and feel a quick sympathy, even though I would be aware that the beggar himself is too disconnected from reality to see their own plight. I would throw him a few bucks, but he would likely just eat it anyway.
I am afraid you would do the same, but you would probably wipe your ass with it first, I suspect.
phoodoo,
Thanks for taking the trouble to lay out how extensively not-bothered you are…
Allan Miller,
Indeed
Oh well done, Phoodoo. You’re shielded from his barbs because you are functionally Charlie Gordon before his operation.
Nothing says “don’t care / not bothered” like a diatribe. I propose a Butthurt ratio: [Don’t care retort string length] / [Triggering comment string length] – units are Phoodoos obviously.
I would not call that “fixing” but an entirely new argument unrelated to the original. And once gain, that entirely new and unrelated argument only works for “accepted statement”.
That’s neither funny, nor smart.
No. Two entirely different arguments.
Then quit while you’re ahead (or at least you think so).
No! Therefore NOT-P. Ouch! So you decided to embarrass yourself further…
All “proofs of evolution” are fallacies. That’s a very important finding and you learned about it right here.
We’re on page 12. These guys will never give up, no matter how many times shown to be wrong. Now if “evolution” were indeed a scientific hypothesis, one would expect at least deference to logic.
This has to be one of the most ironic comments ever.
So true!
Really? I had Dazz and Entropy as “champ” and runner-upper. But perhaps the “champ” is really the one unnoticed.
Enough pleasantries. Let’s get back to business.
Other than [expected and desired] displeasure, do the Darwinistas have anything to add to this topic? Does everyone understand why “proofs of evolution” are indeed fallacies? …that these fallacies cannot be “fixed”?
Come on, this is not the end of the world. There’s still a chance in hell that “evolution” is true (if you only look at this OP and ignore everything else).
Sorry, I accidentally left out a “not” in that post, as I’ve already said. What you’ve left out in this entire thread is any sense whatever. But, naturally, you admit nothing.
Bravo. Fight for the God-given right to know nothing about logic!!
*Raises hand*
Please sir, I have a question:
What was the understanding of the age of the earth at the time when Darwin wrote ‘origin’?
Darwin took Lyell’s Principles of Geology on the Beagle, in which he argued for an old earth. Both were a bit surprised when Kelvin argued it must be younger, but he had not accounted for radioactive heating, unknown at the time, so Darwin went to his grave having thought 300 million plus, but aware of Kelvin’s lower estimate. It was a concern for him.
Nonlin.org,
Let’s not get hung up on what you would or would not call something. [Insert “if I call a tail a leg…” joke here]
I asked you a simple Yes/No question:
If someone takes an example of the Affirming the Consequent fallacy, and negates both statements in the opening conditional, they now have an example of modus tollens, that is, a valid argument. The resulting argument is NOT A FALLACY.
If P, then Q
Q
Therefore P.
(the fallacy)
becomes If not-P, then not-Q
Q
Therefore P.
(modus tollens)
And this is true for any example of affirming the consequent.
You are welcome to dispute the *Truth* of the opening premise, but the validity of the argument does not depend on the truth of the premises.
FFS, logic 101, mate.
So Darwin needed an as yet unproven and risky (at odds with best available knowledge) age of the earth for his theory to survive dis-confirmation. Hmmmm. How does that play with “affirming the consequent”?
DNA_Jock,
Doc, you wrote this:
This logic is NOT valid. You can’t understand why?
It’s a valid argument if we’re talking about validity in the logical sense, your helpless ignorance notwithstanding.
You may mean something different by “valid”, but who cares?
phoodoo,
The logic is valid.
As a consequence of the fact that the logic IS valid, if it turns out that the conclusion is false, then we can safely deduce that at least one of the premises was false.
If, otoh, the logic were invalid, you could not.
Educate yourself about soundness and validity, so you can stop making yourself look stupid.
DNA_Jock,
No idiot (since we are ignoring rules).
First, YOU added the part, where you claimed you can just change was to wasn’t and being saying something that is similar to the original premise, which of course it isn’t. But let’s forget that nonsense for a second. So of course your conclusion is wrong.
But let’s say she wasn’t a soldier. Again your conclusion is wrong! But the premise is still true!
Can birds fly Doc? Yes or no?
Stop making yourself be stupid, its much worse than looking stupid. Aristotle can’t help you here.
So you see a bird, and it can fly, then you deduce that the premise was wrong. But the premise wasn’t wrong, YOU changed Q not me.
Try it as a computer example.
Two variables, ‘birds’ and ‘aunt’, values unknown.
IF ‘birds’ = ‘FLY’
…aunt:=’SOLDIER’
END IF
Just think of it as text, name and contents, not real-world concepts at all. After running, check the value in ‘aunt’. If it’s not ‘SOLDIER’, you know that the value in ‘birds’ is not ‘FLY’ ie, not-soldier means not-fly, inescapably.
If it IS ‘SOLDIER’, of course, you don’t know if it was set to that value before the condition or as a result of it. Your aunt could be a soldier independently of bird flight, which is the general experience! But she can’t NOT = SOLDIER if birds = FLY, given the condition, because SOLDIER is always true if birds=FLY.
You can substitute any variable name and value you like in that test. You’re hung up on knowledge of the world attaching to the words chosen. Substitute A and B and you’d have far less trouble accepting the validity of the logic.
Allan Miller,
Thanks for the advice Allan. We are using words, not numbers. Maybe that’s why Doc doesn’t get it.
If the premises are all true, the conclusion must also be true. See the problem yet.
Can birds fly Allan? Simple question.
Allan Miller,
1. If filibuster, not soon Aquarius in time reflex without frankly.
Now, validate it Allan.
Do words matter?
My illustration used words. Programs aren’t all about numbers.
Why yes, phoodoo. Yes they can.
Why … well, gosh-darnit, I can’t! What can this mean for propositional logic? If I can’t parse a random sentence, I’m wrong?
That’s very general!
Allan Miller,
1. Birds can fly.
2. Kiwis can’t fly.
3. Kiwis aren’t birds.
You’ve not really formulated it correctly. You need an IF … THEN.
Oh it’s so clever how you caught Allan with your deliberate abiguity. You should have asked “can all birds fly?”, or “can some birds fly?”.
When you ask “can birds fly?” there is ambiguity in the question. Do you mean all, or some? The reader can read any of those two into the question, and then answer according to their interpretation.
To some people, some times, yes.
Ill-stated or unclear premises can render problems in propositional logic. That doesn’t undermine the use of propositional logic, it just means you have to be careful with how you express propositions.
Yup. There are numerous difficulties Darwin anticipated – ‘blending inheritance’ was another, and large steps a third (amusingly conflated by nonlin elsewhere). He was intellectually honest enough to state these difficulties, though you’d never know it to hear Creationists go on. And his theory passed these tests as knowledge was gained, which can only be a strength for a scientific theory. Turns out there was enough time, blending inheritance wasn’t an issue, and the general (albeit not universal) rule is smallish steps. It also accounts for facts not even known in his day or for a long time since, such as the patterns embedded deep in the DNA.
Rumraket,
Yes, there’s also a possible implicit ‘only’ which would render bats flightless.
No kidding?
Why don’t you go back about 150 posts and you might see that is exactly what I already said.
But no no, Doc and Walto, they got it all figured out see. Just go back and negate everything.
But rest assured, you will walk that statement back as soon as you realize that is exactly my point.
No, if that’s your point I agree with it. I have no problem disagreeing with people in my “camp” and stating as much if I think they’re wrong.
The forms are what they are, whatever the propositions mean.
P
P then Q
Q
is always valid, whatever propositions you stick in there. If the premises are true, the conclusion must be as well. However, you may not be able to tell what the form of some argument is because the propositions are complicated or unclear and you may not be able to tell whether any of the propositions are true. In those cases you can’t tell whether an argument is SOUND. This was all explained in the first few posts.
walto,
Don’t believe everything Aristotle told you Walto.
Heavens, no, phoodoo. We agree with you that propositional logic, with its true or false, no third options allowed, statements is not how science works. We’ve been clear about that all along.
Kantian Naturalist explained this very clearly on the first page of comments.
You might also remember:
[The trap being: you agree, thus the OP is rubbish]
Would you be a dear, and let nonlin know?
[The fact that the neither phoodoo nor (surprisingly) nonlin understand how logic works has been a rather entertaining sidetrack, that has nothing to do with evolution or science.]
ETA” walto put it rather well here
That’s good advice for Aquinas.
This is a valid form if you stick an “All” in front of “Birds”. It’s discussed in Aristotle. But it’s not propositional logic. You have to understand the sentences and understand the nature of the quantifiers “all” and “some” to know that it’s valid. The propositional form there is just
P
Q
R
The thing is, Affirming the Consequent is a fallacy of PROPOSITIONAL LOGIC.
(Why I’m wasting my time with this is a bigger mystery than whether God exists or there’s life on earth.)
No, we are not ignoring rules.
We are being somewhat lax, because a strict enforcement of rules can be as disruptive as rule violations.
Please try to follow the rules, lest we decide to enforce more strictly.
We don’t have to believe everything Aristotle told us to agree with Aristotle on some things.
Aristotle rather famously argued that women have fewer teeth than men. And that’s where we see the difference between science and philosophical navel-gazing, because had he bothered to just ask to look into the mouth of some women he’d have realized navel-gazing is inferior to observation.
Philosophy and metaphysics is important for teaching us how to reason correctly, but we often times have to check our premises and asumptions against real-world observations and let the results guide our thinking.
Neil Rickert,
Then warn everyone for crying out loud!
What are you trying to do, pull an Alan?
I already know all about your biases Neil.
walto,
Its premises and a conclusion. When did I say that statement was a propositional argument? Its an argument.
Who would have guessed that putting an all in there would wipe away the ambiguity? I’ll be darn.
What a brilliant observation Walto
If there are no third options allowed then an argument with more then two options is invalid, is that what you are telling me?
Still waiting for you to justify this one Jock.
Then why isn’t the converse also true? The cat seems to have got your tongue on that one.
phoodoo,
The observation you should take on board is the ‘propositional’ one. That’s what the OP is about; not simple statements but conditional ones – ones which would need an ‘If’ to be rendered algorithmically. If you’re just intent on arguing about simple statements, you are missing the point. It’s standard behaviour, and I wouldn’t have you any other way. You dig a shallow hole, and snarl at anyone who comes near. But that’s your error, accept it or no.
What Nonlin has been telling you all along is that the science community pretends there is logic in the deductive assertion of evolution as science. And he is saying that is bullshit.
All you are doing is agreeing with him that indeed, saying the evidence for evolution is based on logic is nonsense.
You would think you could have figured out by now that this is what his OP says.
You think no one in the science community makes the arguments for evolution that Nonlin objected to? Is you head caught in a lab jacket, and you can’t see?
Allan Miller,
Were you snarling when you wrote that Allan?
You haven’t understand the whole point of this thread from the beginning, but glad you popped out of your hole to say hello.