# 18

### Facsimile

### Transcription

15

fact expressed

If it both rains and blows a pear is ripe.

[Go to Vol 2 p 40 (MS 456)]

~~We now have three tules of necessary inference.~~

First, from any premiss A, we can necessarily

conclude B, if and only if we know that it

is not the case that A is true while B is false.

We may, therefore, rub out everything on

the board, because we know that the blank

sheet of assertion asserts nothing false. Hence

if two graphs are written one may erase either

of them, because each has the same signification

as if it stood alone, and either standing alone

might be erased.

But now if any graph, G, could if it were scribed on the

sheet of assertion be transformed into another

graph H without fear of introducing falsity

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