covers multiplication of whole numbers, not fractions. Rather, a definition encompassing both would be: multiplication is finding a quantity whose ratio to one factor is the same as the ratio of one to the other factor. Thus, if one is told, ‘Multiply one-half by one-quarter,’ the result is one-eighth, whose ratio to one-quarter is the same as the ratio of one-half to one.”
Although this is correct, it is clear that someone who has money and wishes to divide it equally among a known number of people would be tormenting himself to no benefit if he insisted on understanding all this before making the division. He might not understand this explanation, and it might present him with difficulties.
Likewise, evidence and demonstration guide one to what one seeks and lead one to the intended conclusion. Whenever something entails something else, it can be used as evidence for it. Hence the definition:
“Evidence is that which, when soundly considered, leads to knowledge or probable belief.”
The point is that whatever entails something else, such that the latter necessarily follows from it, serves as evidence and demonstration for it—whether both involve existence, both involve nonexistence, or one involves existence and the other nonexistence. Thus, invariably, the evidence entails what it establishes, and what it establishes necessarily follows from the evidence.
The evidence may consist of a single premise which, once known, makes the desired conclusion known. The person reasoning may need two premises, or may need three, four, five, or more. There is no fixed number that applies equally to everyone in every inquiry; rather, this