Deduction

Tags

logic

Is the process of [see page 29, inferring] facts from true propositions using propositional connectives.

Deduction is a process with 3 steps:

1. Start from premises (true propositions).
2. Construct an inference from these;
3. This gives conclusions, as a truth value.

Babies Can't Manage Crocodiles example

As an [see page 42, example] deduction:

Consider the premises:

1. Babies are illogical (\( B \implies I \)).
2. Nobody is despised who can manage a crocodile (\( M \implies \neg D \)).
3. Illogical people are despised (\( I \implies D \)).

\begin{align} B &\implies D \
D &\implies \neg M \
B &\implies \neg M \end{align}

Which leads to the conclusion babies can't manage crocodiles.