 In a 1990 paper , " Elephants Don 't Play Chess , " robotics researcher Rodney Brooks took direct aim at the physical symbol system hypothesis , arguing that symbols are not always necessary since " the world is its own best model . It is always exactly up to date . It always has every detail there is to be known . The trick is to sense it appropriately and often enough . " In the 80s and 90s , many cognitive scientists also rejected the symbol processing model of the mind and argued that the body was essential for reasoning , a theory called the embodied mind thesis . 
 In a 1990 paper , " Elephants Don 't Play Chess , " robotics researcher Rodney Brooks took direct aim at the physical symbol system hypothesis , arguing that symbols <a href='negative_concord' title='1'><mark>are</mark></a> <a href='negative_concord' title='2'><mark>not</mark></a>always necessary since " the world <a href='drop_aux' title='3'><mark>is</mark></a>its own best model . It <a href='drop_aux' title='4'><mark>is</mark></a>always exactly up to date . It always <a href='got' title='5'><mark>has</mark></a> every detail <a href='dey_it' title='6'><mark>there</mark></a> is to be known . The trick is to sense it appropriately and often enough . " In the 80s and 90s , many cognitive scientists also rejected the symbol processing model of the mind and argued that the body was essential for reasoning , a theory called the embodied mind thesis . 
In a 1990 paper , " Elephants Don 't Play Chess , " robotics researcher Rodney Brooks took direct aim at the physical symbol system hypothesis , arguing dat symbols ain't always necessary since " the world its own best model . It always exactly up to date . It always got every detail it is to be known . da trick is to sense it appropriately and often enough . " In tda80s and 90s , many cognitive scientists also rejected the symbol processing model of the mind and argued that the body was essential for reasoning , a theory called the embodied mind thesis .