[□] □ □ □ □
[□=□] □ □ □ □
[□ & □] □ □ □ □
As such , they do not know or care why the Americans came to fight half a century ago . Some companies market to customers they do n't know or understand . The study of complex adaptive matter , part of the general study of complexity , attempts to understand what happens when scientists put enough things together they do n't know or for which they ca n't make predictions .