How many famous one-liners are oft-quoted but may be sometimes or even always wrong? I can think of a few:
What doesn't kill you makes you stronger.
Thank Nietszche for this one. It
can be true in cases, but sadly, there are a huge number of things which don't kill you but leave you weakened. Many childhood diseases leave the victim alive but crippled for life. A spinal-cord injury that turns you into a quadriplegic can hardly be said to make you stronger. A childhood abuse trauma tends to cause a lifetime of neuroses. In fact, I think this quote is actually based on a widespread misconception of evolution theory's "survival of the fittest" mechanism. In evolution, the strong survive. This does
not mean that surviving something actually makes you stronger; it means that those who are
already stronger are more likely to survive.
Absence makes the heart grow fonder.
This one is bullshit as far as I'm concerned. While separation may be good for healing old wounds (except in the case of the obsessive; see people like Darkstar, who obsesses over me constantly, and Bernd Schneider, who has obsessed over me for the whole 3-year period since we exchanged E-mail; WTF is with these people?), it generally destroys marriages.
If you don't have anything good to say, say nothing at all.
Ah, so if someone does something horrible, you should keep your trap shut? That kind of thing is known as apathy. As an engineer, I could face serious disciplinary action if I said nothing when witnessing an example of serious incompetence, even if it's not my direct responsibility.
There are no stupid questions, only stupid answers.
This is one of the most blatantly false "wise sayings" you'll ever run across. Sorry, but there
are stupid questions, and I've seen more than my share. For example, the creationist question: "if evolution is true, then why do apes still exist today?" is definitely a stupid question.