Carnap's example of the process of verification
-P1: 'This key is made of iron'. Many ways of verifying: e.g.,: place the key near a magnet; then perceive that the key is attracted
-deduction made in this way: Premises: P1 & P2: 'If an iron thing is placed near a magnet, it is attracted'; this is a physical law, already verified
-P3: 'This object – a bar – is a magnet'; already verified
-P4: 'The key is placed near the bar'; now directly verified by our observation
-from these 4 premises we can deduce the conclusion: P5: 'The key will now be attracted by the bar'