self-evidence the property of being self-evident. Only true propositions (or truths) are self-evident, though false propositions can appear to be self-evident. It is widely held that a true proposition is self-evident if and only if one would be justified in believing it if one adequately understood it. Some would also require that self-evident propositions are known if believed on the basis of such an understanding. Some self-evident propositions are obvious, such as the proposition that all stags are male, but others are not, since it may take considerable reflection to achieve an adequate understanding of them. That slavery is wrong and that there is no knowledge of falsehoods are perhaps examples of the latter. Not all obvious propositions are self-evident, e.g., it is obvious that a stone will fall if dropped, but adequate understanding of that claim does not by itself justify one in believing it. An obvious proposition is one that immediately seems true for anyone who adequately understands it, but its obviousness may rest on wellknown and commonly accepted empirical facts, not on understanding.
All analytic propositions are self-evident but not all self-evident propositions are analytic. The propositions that if A is older than B, then B is younger than A, and that no object can be red and green all over at the same time and in the same respects, are arguably self-evident but not analytic. All self-evident propositions are necessary, for one could not be justified in believing a contingent proposition simply in virtue of understanding it. However, not all necessary propositions are self-evident, e.g., that water is H2O and that temperature is the measure of the molecular activity in substances are necessary but not self-evident. A proposition can appear to be selfevident even though it is not. For instance, the proposition that all unmarried adult males are bachelors will appear self-evident to many until they consider that the pope is such a male. A proposition may appear self-evident to some but not to others, even though it must either have or lack the property of being self-evident. Self-evident propositions are knowable non-empirically, or a priori, but some propositions knowable a priori are not self-evident, e.g., certain conclusions of long and difficult chains of mathematical reasoning.
See also ANALYTIC – SYNTHETIC DISTINC — TION , A PRIORI , KANT, NECESSITY, RATIONAL — IS. B.R.