An extensive list of logical fallacies

[Scav]

http://www.mnforsustain.org/student_logical_fallacies_with_references.htm

Linked is a wonderful list of logical fallacies, complete with examples and sources. It's a bit sobering to read through, because every one of us makes a fair number of the described mistakes.

Just because your thinking is fallacious doesn't mean it's wrong, per se, but it does mean your thinking needs deeper examination. For instance, discounting someone's argument because they have a personal interest at stake might end up being correct, but it could just as easily be wrong and should not supply the foundation of your argument.

An example:

Appeal to Consequences (argumentum ad consequentiam)

Definition: The author points to the disagreeable consequences of holding a particular belief in order to show that this belief is false.

Example:
(i) You can't agree that evolution is true, because if it were, then we would be no better than monkeys and apes.
(ii) You must believe in God, for otherwise life would have no meaning. (Perhaps, but it is equally possible that since life has no meaning that God does not exist.)

Proof: Identify the consequences to and argue that what we want to be the case does not affect what is in fact the case.
Reference: (Cedarblom and Paulsen: 100, Davis: 63)

 

[blazedaces]

Here is another extensive list of basically the same things (just in case you want to read through both ):

http://www.editthis.info/logic/Informal_Fallacies

-blazed

 

[snex]

it should be noted that most debates cant be resolved without resorting to logical fallacies. the problem is that we live in a world where deductive logic cannot simply be applied unless we know the axioms of the world. we dont know the axioms of the world, so we are forced to use inductive reasoning, which is technically a fallacy of affirming the consequent.

the example you brought up also is a perfect example of a fallacy we need to make in certain debates. when debating abortion or capital punishment, for example, you NEED to appeal to the consequences because thats really what the debate is about - which option has more desirable consequences.

if we knew the axioms of the universe and morality, then it would be trivial to easily determine most things we want to know, and debating wouldnt even exist. you would simply generate the theorem and thered be no debate.

 

[blazedaces]

so we are forced to use inductive reasoning, which is technically a fallacy of affirming the consequent.

Does it still count as affirming the consequent if we don't actually know that the relationship A then B exists? I mean, it could very well be that some third variable Z is causing both A and B. We must be open to the possibility. I'm just saying induction boils down to committing worse then just an appeal to the consequent at times...

And as for your first point, isn't that hopefully one of the reasons we're striving for a unified theory of everything in theoretical physics/science?

-blazed

 

[snex]

Does it still count as affirming the consequent if we don't actually know that the relationship A then B exists? I mean, it could very well be that some third variable Z is causing both A and B. We must be open to the possibility. I'm just saying induction boils down to committing worse then just an appeal to the consequent at times...

inductive reasoning is always affirming the consequent. affirming the consequent is an argument in the following form:

A -> B
B
therefore A

all of science works this way, except that B is a compound proposition, and the more elements it has, the more confident of A we are. for example:

big bang -> CMBR at 2.7 K
CMBR at 2.7 K is observed
therefore the big bang happened

big bang -> (CMBR at 2.7 K) & (all galaxies show red shift)
CMBR at 2.7 K is observed
all galaxies do show red shift
therefore the big bang happened.

see? affirming the consequent.

And as for your first point, isn't that hopefully one of the reasons we're striving for a unified theory of everything in theoretical physics/science?

even if we got one, i suspect it would be so far removed from everyday reality that generating theorems about things like biology would take much longer than traditional scientific methods - and of course even if we did have the axioms, godel still presents a problem.

 

[AltF4]

Godel only says that there will be true statements in the system which are unprovable from within the system. So you can never be sure that you've got all the true statements, because there COULD always be one out there that you just haven't seen yet.

But it's entirely conceivable that you DO discover all true statements within the system. The incompleteness theorem doesn't prevent us from attaining complete knowledge, just from ever knowing if we've gotten there.


But yes, I support this thread. It should be a sticky for sure. A must read for new debaters.

 

[blazedaces]

Well I guess I sort of agree with everything you say... (sort of a pointless post?)

-blazed