Navigating modernity can be tough. Luckily philosophers, poets, and great thinkers over the centuries has developed a number of mental shortcuts, in the form of heuristics, razors, guillotines, and other aphorisms. We've collected the most important ones here in a 'cheat sheet' of sorts. Memorize these, and you may never look at the world in the same way again...  

Alder’s Razor
If something cannot be settled by experiment or observation, then it is not worthy of debate.

Chesterton’s Fence
Reforms should not be made until the reasons behind the existing state of affairs is understood.

Duck Test
The duck test is a form of abductive reasoning, usually expressed as "If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck."

Grice's razor (also known as Giume's razor)
As a principle of parsimony, conversational implications are to be preferred over semantic context for linguistic explanations. AKA Address what the speaker actually meant, instead of addressing the literal meaning of what they actually said

Hanlon’s Razor
Never Attribute to malice that which can be adequately explained by stupidity.

Hitchen’s Razor
What can be asserted without evidence can also be dismissed without evidence.

Hobson’s Choice
A free choice where only one choice is offered

Hume’s Guillotine
If the cause, assigned for any effect, be not sufficient to produce it, we must either reject that cause or add to it such qualities as will give it a just proportion to the effect.

Occam's Razor
When confronted with competing explanations, often the explanation with the fewest assumptions is the correct explanation.

Maslow’s Hammer
To treat everything as if it were a nail, If the only tool you have is a hammer.

Popper's Falsifiability Principle
For a theory to be considered scientific, it must be falsifiable.

Sagan Standard
Extraordinary claims require extraordinary evidence.

Shirky Principle
Institutions will try to preserve the problem to which they are the solution.