| | |
| Paragraph 1 |
Demonstrative knowledge must rest on necessary basic
truths; |
| Paragraph 2 |
We must either state the case thus, or else premise that the
conclusion of demonstration is necessary and that a demonstrated
conclusion cannot be other than it is, and then infer that the
conclusion must be developed from necessary premisses. |
| Paragraph 3 |
A further proof that the conclusion must be the development of
necessary premisses is as follows. |
| Paragraph 4 |
When the conclusion is necessary, the middle through which it was
proved may yet quite easily be non-necessary. |
| Paragraph 5 |
To sum up, then: |
| Paragraph 6 |
Of accidents that are not essential according to our definition of
essential there is no demonstrative knowledge; |
| Paragraph 7 |
Since it is just those attributes within every genus which are
essential and possessed by their respective subjects as such that
are necessary it is clear that both the conclusions and the
premisses of demonstrations which produce scientific knowledge are
essential. |