Even if you are pretty solid in your understanding of life, we can always get great reminders from the older, wiser people who have come before us. I do enjoy the fact that they are all grouped together. A couple of rules of thumb to help navigate through life.
Occam's razor: Simpler explanations are more likely to be correct;
Hanlon's razor: Never attribute to malice that which can be explained by stupidity.
Hitchens's razor: What can be asserted without evidence can be dismissed without evidence.
Hume's guillotine: What ought to be cannot be deduced from what is.
Alder's razor: If something cannot be settled by experiment or observation, then it is not worthy of debate.
Sagan standard: Extraordinary claims require extraordinary evidence.
Popper's falsifiability principle: For a theory to be considered scientific, it must be falsifiable.
Grice's razor: Conversational implications are to be preferred over semantic context for linguistic explanations.
“For small creatures such as we, the vastness is bearable only through love…”
― Carl Sagan
The age old sages who perfected the art of cutting the fat