What's your favorite logical fallacy, mental model, cognitive bias, phenomenon, etc. Wikipedia article?

The decoy effect is one of my favourites. It occurs when your preference for one of two options changes dramatically when a third, similar but less attractive option is added into the mix.

For example, in Dan Ariely's book Predictably Irrational was a true case used by The Economist magazine. The subscription screen presented three options:

Web subscription - US $59.00. One-year subscription to Economist.com. Includes online access to all articles from The Economist since 1997

Print subscription - US $125.00. One-year subscription to the print edition of The Economist

Print & web subscription - US $125.00. One-year subscription to the print edition of The Economist and online access to all articles from The Economist since 1997.

Given these choices, 16% of the students in the experiment conducted by Ariely chose the first option, 0% chose the middle option, and 84% chose the third option. Even though nobody picked the second option, when he removed that option the result was the inverse: 68% of the students picked the online-only option, and 32% chose the print and web option.

The idea is that you'd spend the money on the option you think is "a steal" even though you had no previous plans of purchasing it.

Favorite Wikipedia article: https://en.m.wikipedia.org/wiki/Wikipedia:Getting_to_Philosophy

Almost links eventually lead to philosophy!

Chesterton's Fence is a good one that I'm working on. Never get rid of or dismiss something until you've understood how and why it came to be and what purpose it served.

Something like that.

Also, in the other direction, Second Order Thinking, do a triple T chart and describe the shor, medium, and long term knock-on consequences or experiental results it is likely to yield

I don't have any specific Wikipedia article, but if you want more in depth reading material, Thinking Fast and Slow is probably the authoritative work on bias, by one of the central figures to the emergence of behavioral economics.

Misbehaving is another.

The vast majority of books I read that touch on decision making or bias cite at least one or Daniel Kahneman or Richard Thaler, and they're both reasonably accessible. If you want something more accessible than that, Thinking in Bets covers similar ground. Annie Duke targets general audiences well, but all of her books also make her strong foundation in the field of psychology and what the research supports pretty clear.

Edit: You know what? I will pick one special one. Hindsight bias, or as Annie Duke calls it, resulting. A good decision doesn't become a bad one when the result doesn't work out the way you want. It is an opportunity to re-evaluate, and see if there were things you could have predicted given the information you reasonably had available at the time, but, you should do the same with decisions that work out. A good decision can result in a bad outcome and a bad decision can result in a good outcome. Make a continuous effort to improve your process, but separate the process from the results. Mortgaging your house to make a bet on the Super Bowl wasn't genius if your team won.

I don't know about favorite, but high on the mess-with-the-head factor.

https://en.wikipedia.org/wiki/Capgras_delusion

Capgras delusion or Capgras syndrome is a psychiatric disorder in which a person holds a delusion that a friend, spouse, parent, another close family member, or pet has been replaced by an identical impostor.[a] It is named after Joseph Capgras (1873–1950), the French psychiatrist who first described the disorder.

In a 1990 paper published in the British Journal of Psychiatry, psychologists Hadyn Ellis and Andy Young hypothesized that patients with Capgras delusion may have a "mirror image" or double dissociation of prosopagnosia, in that their conscious ability to recognize faces was intact, but they might have damage to the system which produces the automatic emotional arousal to familiar faces.[21] This might lead to the experience of recognizing someone while feeling something was not "quite right" about them. In 1997, Ellis and his colleagues published a study of five patients with Capgras delusion (all diagnosed with schizophrenia) and confirmed that although they could consciously recognize the faces, they did not show the normal automatic emotional arousal response.[22] The same low level of autonomic response was shown in the presence of strangers. Young (2008) has theorized that this means that patients with the disease experience a "loss" of familiarity, not a "lack" of it.[23] Further evidence for this explanation comes from other studies measuring galvanic skin responses (GSR) to faces. A patient with Capgras delusion showed reduced GSRs to faces in spite of normal face recognition.[24] This theory for the causes of Capgras delusion was summarised in Trends in Cognitive Sciences in 2001.[2]

Dunbar's number especially when used to contextualize the potential limits of human organization, such as relying only hiring friends and family. The chances that of the 200 people who probably know pretty well also happen to be the best candidate for an important task is low. Most exaggerating case of this is presidential nominees for positions. Like of course it's the same guy for a few admins, it's who they know that is remotely qualified.

The self as an illusion is an interesting concept to play with. We think of ourselves as identities so that we can operate socially. However when one examines the moment to moment experience of consciousness the self is nowhere to be found.

The Book Thinking Fast and Slow by Daniel Kahnneman. Weird self help name, but its a book on biases, research which Kahnneman won the nobel prize. Once I started questioning my preconceptions it completely changed my whole perspective on the world. Its like that list of fallacies that you study in philo 101, but they're not like dialogical fallacies they appear in our own thinking. And "experts" are more likely to get fooled in their own fields of research than laypeople when asked trick questions

I couldn't imagine having a "favorite" mind impediment, by their nature they're not without equal hampering potential. I can just say though which fascinate me.

• Appeal to the masses. I deal with this a lot. Some will say or imply "the masses think something, therefore it must be true". Most people will treat "headcanon" and "canon" as separate but they'll treat it the same. Ever had words put into your mouth with them insisting you meant something you didn't? By their logic, those words are now your own. This is related to so many of the things people falsely think about me, which is "in" to do so they accumulate.

• Judgment by association. Same people usually, again something I'm very familiar with. I'm sure one of the reasons for my social situation is because others are suspect once they associate with me who is often suspect. The words "show me who your friends are and I'll show you who you are" are even often explicitly the words that serve as the heart of some peoples' "awareness" campaigns. It is persecution based on your interests.

• "If you're not with me, you're my enemy" is one I can quote Anakin, Jesus, and several Democrat politicians on. It is probably wishful thinking (...which reminds me of another fallacious mindset, treat that as a bonus once you read into those), but my inner Christian likes to think Jesus didn't mean it this way, because it's irresponsible, for a lack of a better word. I see people all the time forced to make such choices as if it isn't anti-diplomatic. The fact Anakin memed it at least gives me "favoritism" towards it though.