An introduction to the art of logick composed for the use of English schools, and all such who having no opportunity of being instructed in the Latine tongue ... / by John Newton ...

CHAP. VIII. Of an Imperfect Demonstration or the Demonstration, What.

HAving hitherto spoken of the principal Demonstration, or the Demonstration ••hy? the next is the less principal, or the ••emonstration What? and which leaveth an ••mperfect knowledge, and is twofold; the ••ne is from the effect, the other from a remote ••ause.

The first of these collecteth the cause from ••ome sensible effect; for example

• Every thing that is risible is rational,
• Every man is risible,
• Therefore every man is rational.

Here the medium is the next effect, and the predicate is the cause of the conclusion.

2. The second of these demonstrations collecteth the effect from some remote cause▪ for example.

• That which hath not a sensitive soul doth not breath,
• A Plant hath not a sensitive soul,
• Therefore a plant doth not breath.

3. A Demonstration from the effect may be affirmative in Barbara, and sometimes ne∣gative, though seldome, in Camestres.

4. A demonstration from a remote cause i•• negative, very seldome affirmative, and con∣sequently is restrained to the third figure i•• Camestres: for example.

• Every risible thing is an animal,
• No Tree is an animal,
• Therefore no Tree is risible.

5. Demonstration from the effect 〈◊〉〈◊〉 more excellent than from a remote cause.

• 1. In respect of the form, the one be¦ing affirmative in Barbara, the other negati•• in Camestres.
• ...

• 2. In respect of the matter for in the one the propositions are most necessarily true, and differeth nothing from the most perfect Demonstration, but in placing of the terms, and begetteth a perfect know∣ledge not simply, but in its kind: but the Demonstration from the remote cause is made of less necessary, and not immediate propositions, nor doth it beget a know∣••edge that is perfect in its own kind, and ••n which the mind may rest satisfied; yet both of them are so perfect, that they are either of them sufficientl to beget such a knowledge as to give us satisfaction of the being, or not being of a thing.