The "
there exists" symbol "
∃", and many others, were created by the Italian mathematician Giuseppe Peano (1858-1932), many by reversing letters or turning them upside down.
Peano created the "
or" symbol as "
∨" from the letter "
v" starting the Latin word
"vel" ≈ "or". The "
and" symbol "
∧" is an upside down "
or" symbol.
Other mathematicians then followed this convention in creating more symbols over time. One such symbol was the "
for all" symbol "
∀" first used in 1935 by logician Gerhard Gentzen (1909-1945) and called it, in German, "
All-Zeichen", the "
all character"
