time-lag argument

main aim

to show that mind-independent objects are not the immediate objects of perception

premise one

in many or all examples of perception there is a time-delay between what is happening and what is perceived

conclusion one

so mind independent objects are not being perceived immediately

conclusion two

so they are not the immediate objects of perception

premise twod

direct realism claims that mind independent objects are the immediate objects of perception

conclusion three

so direct realism is false

development

the speed of light and sound are finite so we cannot access information about objects immediately
e.g. light from the sun takes about 8 minutes to reach the earth, so we perceive the sun how it was 8 minutes ago

development two

the presence of these delays implies that there is some intermediate step in perception, and so perception is not direct