What does this quote mean a man who stands for nothing will fall for anything

When it is said one must stand for something, it does not mean that one must literally be standing, what is generally meant is that one must figuratively fight for something he or she believes in.  When it is said that someone falls for something, it is generally meant that one either fell in love with something or that one was deceived/is gullible.  In the instance of the quotation provided, however, what is meant is probably the latter.  That said, one interpretation of the quotation, “A man who stands for nothing will fall for anything” is that if one is not passionate about something or does not firmly believe in something, one will easily believe in anything to the point of being easily fooled.

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