If the Afghanistan war was about spread­ing free­dom, there would be elec­tions. There have been recent elec­tions in Afghanistan. Thus, the Afghanistan war is spread­ing freedom.

Well, what if the votes are not freely counted?  What if free­dom is not the goal, and the elec­tions are merely a side show?  What if the elec­tions really are an indi­ca­tion that free­dom is grow­ing in Afghanistan?

The above argu­ment assumes too much and pro­vides too lit­tle for such a def­i­nite con­clu­sion.  It cherry picks a fact and tries to prove an assump­tion.  There would not be any­thing wrong with this, if it was pre­sented as a hypoth­e­sis, or if it were one of many rea­sons.  With free­dom being such a com­plex con­cept, it’s rather sim­plis­tic to think that you can prove it’s exis­tence with just one sign of it.

This argu­ment takes the form: IF P, then Q. Q. There­fore, P.  It is com­mon to fall for this fal­lacy as we were taught early on that some con­cepts are inter­change­able, such as 1 + 2 = 3 an  2 + 1 = 3.  But, this is not always depend­able, as 2 / 1 = 2 and 1 / 2 = 0.5.

It rains in Spain.  It is rain­ing out­side.  WOW!  This must mean that we’re in Spain!

We were all kids once, so we all rea­soned like this as well.  Until we learn that it can rain any­where in the world, this argu­ment makes sense to the igno­rant.  Affirm­ing the Con­se­quent assumes that real­ity is sim­ple and can be relied upon for­wards and back­wards.  It’s typ­i­cally fal­la­cious to rea­son this way as most def­i­n­i­tions have mul­ti­ple mean­ings and can apply to a myr­iad of sit­u­a­tions.  It is rare to come across a sound argu­ment that affirms the consequent.

All cops have badges.  The guy at the door­way has a badge.  He must be a cop.

I think every­one has let the ‘pow­er­guy’ check the power meters, with­out much hes­i­ta­tion.  It is merely the uni­form that is gain­ing our trust.  An dis­grun­tled ex-employee who still has his shirt can get into any­where if he does it right.  Some­times it’s a mat­ter of choice whether to let this fal­lacy slide.  Sure, this guy may have faked his badge, but are you will­ing to risk get­ting into trou­ble just because of a pos­si­bil­ity?  He may not be a cop, but maybe it’s bests to give him the ben­e­fit of the doubt.

VIP Mem­bers have the pass­word.  Bill spoke the right pass­word.  Bill is VIP

This is not a fal­lacy.  In this sit­u­a­tion, there was only one pos­si­bil­ity and it was met fully.  It may still be the case that Bill is not VIP but merely over­heard the pass­word over lunch.  This ver­sion is often sound, but should not be fully trusted either.

Fire alarms ring when there is fire.  The alarm is ring­ing.  Get out!!!

I had lunch with a friend a few months ago, and right after we fin­ished our shrimp appe­tizer the alarm started a steady nag.  The waiter said, “Oh, it’s just the alarm going off.  Some­one must have hit it or some­thing.” and walked away uncon­cerned.  I won­dered if some­one hit the alarm for a rea­son? I was lost in thought and won­dered why these fire alarms are always just a drill.  I never need to run from any real fires.  My friend, more con­cerned than me, told me that if the alarms go to phase 2, we’re outta here.  He sipped his pop and bit his burger.  The nag­ging dou­bled.  “Ok, maybe it’s for real” observed the waiter, and we ditched.  Out­side we noticed black smoke ris­ing over the drug store.  Wow, a real alarm.  More often than not a fire alarm ring­ing is an acci­dent or a drill, and rarely means fire.  This ver­sion is some­times sound, but should not fully be dis­missed either.

With­out water, there would be no life on Earth.  There is water on Europa.  There­fore, there is life on Europa!

Not so fast Mr. Sci­en­tist.  We don’t know for sure that Water leads to life, we just know that it is very con­ve­nient for life.  Wannabe sci­en­tists often fall for the fal­lacy.  They want to jump to con­clu­sions because it implies a great break­through.  The pres­ence of life on Europa will not be con­firmed until we con­firm it, with video cam­eras, on Europa (or maybe bac­te­ria sam­ples are brought back to Earth?)  Until then, you will need a lot more con­jec­ture than just water to con­vince me that life HAS to be on Jupiter’s moon Europa.  This fal­lacy can be eas­ily fixed by being less absolute and more hypothetical.

Bach­e­lors are sin­gle men.  Joe is sin­gle.  Thus, Joe is a bachelor.

This time you can affirm the con­se­quent and be absolutely sound.  This is a cat­e­gor­i­cal affir­ma­tion.  If this con­clu­sion were not sound, then it con­tra­dicts the sole mean­ing of bach­e­lor.  It can quite eas­ily become wrong if the word bach­e­lor took on a new mean­ing as some sort of cook­ing utensil.

This line of rea­son­ing hap­pens to be easy to avoid: restrict your usage of absolutes.  Flesh out your argu­ment with more facts.  Acknowl­edge and rule out other pos­si­bil­i­ties.  Affirm the truth, not the consequent!