Testing the water
Consider the following propositions:
"No object can appear both red and green at the same time." (I'm excluding polka dots, stripes and the like. You know what I mean here.)
"No object can appear to be colored as a hue that is not an element of {c | c falls within what we commonly call or conceive of as the visual spectrum}"
1. Do we know these propositions?
2. Do we know these propositions a priori?
3. Do we know these propositions with certainty?
And, of course: Why, or why not?
"No object can appear both red and green at the same time." (I'm excluding polka dots, stripes and the like. You know what I mean here.)
"No object can appear to be colored as a hue that is not an element of {c | c falls within what we commonly call or conceive of as the visual spectrum}"
1. Do we know these propositions?
2. Do we know these propositions a priori?
3. Do we know these propositions with certainty?
And, of course: Why, or why not?