The some can also be said of false propositions in that the...

The some can also be said of false propositions in that the fallacy of some of them can be understood independent of experience while only the help of experience can ascertain that of others. In technical terms, proposition of the second kind are called a posterior. Therefore a prior proposition is one whose truth or falsity can only be determined by an empirical method. It is important at this junction to consider the following point.

The first Point The concepts employed in a proposition may have been acquired through the sense but it may still be a priori if we can determine its truth or falsity by a rational method and independent of the senses, like many geometrical propositions. Which though contain many sensible concepts, such as dot?Line surface, circle, triangle etc. are all a priori since we can determine their truth or falsity by the rational method and without the help of the sense.

In general the way parts of a proposition or the whole proposition have entered the mind, whether it is through dreams, inspiration etc. Does not make a proposition a priori or a posterior. Whether a proposition a is a posterior depends only on the way we determine its truth or falsity. The Second Point Aposterior proposition is exceptive; that is, observed counter - example can only question it universality while retains its validity or other cases.

In other words, though that proposition is false in its universality, in its more particular form it may be true. Consequently, another universal proposition but with a particular subject replaces the invalidated universal proposition. A prior proposition, however is non-exceptive, that is a rational counter example will indicate the total invalidity of the proposition and we cannot claim its truth in any other case.

For example suppose a true geometrical proof demonstrates that the total sum of the angles of an equilateral triangle is not 180 degree. This counter example will show that triangle is 180 degree is not valid and the invalidity of that cannot rationally judge that the total sum of the angle of any triangle is 180 degree.