Final answer:
The obverse of a false proposition is not necessarily true; truth is determined by a proposition's conformity to reality and must not derive from false premises, according to the 'no false lemmas' condition.
Step-by-step explanation:
The notion that the obverse of a false proposition is a true proposition is not universally accurate. In philosophical terms, the truth or falsehood of a proposition is not strictly determined by the truth values of another related proposition. According to Gilbert Harman's condition of "no false lemmas," a true belief must not be inferred from any false premises. It highlights the importance of each step or premise in the reasoning process to be true for the overall conclusion to be seen as knowledge.
For instance, the correspondence theory of truth asserts that a proposition is true when it accurately reflects reality. Yet if a truth is derived from a falsehood, despite being accurate in its final form, it lacks a certain legitimacy in terms of knowledge. Aristotle's view also suggests that for a statement to be true, it must accurately represent the subject it is describing - effectively saying 'what is, is,' and 'what is not, is not.' So, in this traditional sense, the obverse of a false proposition is not necessarily true - truth is determined by a proposition's conformity to reality, not merely by the falseness of another.