Auxiliary
if; in case; if it is the case that; if it is true that
hypothetical form of the copula だ, from なり and sometimes classed as a particle
感情によって理性が曇らされているままにしておくならば、我々は、常に見当違いのことをしてしまうだろう。If we let our reasoning power be overshadowed by our emotions, we would be barking up the wrong tree all the time. as for; on the topic of
Conjunction
if that's the case; if so; that being the case
ColloquialAbbreviationsee それなら
if possible; if circumstances allow
Also written ならば