If a man supports Celtic one day and Rangers the next then he is fickle but not necessarily illogical. From this starting point, and assuming no previous knowledge of the subject, Wilfrid Hodges (http://wilfridhodges.co.uk/ and http://en.wikipedia.org/wiki/Wilfrid_Hodges) takes the reader through the whole gamut of logical expressions in a simple and lively way. Readers who are more mathematically adventurous will find optional sections introducing more challenging material. Many of us were exposed to this primer at a tender age, and remember it with a blend of terror and affection! Its object is laudable – the practice of clarity in thought.
Follow up with the admirably brief Logic: A Very Short Introduction by Graham Priest (http://www.amazon.co.uk/Logic-Very-Short-Introduction-Introductions/dp/0192893203/ref=sr_1_1?ie=UTF8&qid=1386140319&sr=8-1&keywords=logic+very+short+introduction)
Follow up also on the Web with an excellent group of entries in The Stanford Encyclopaedia (http://plato.stanford.edu/entries/logic-epistemic/)
For a historical background to Logic, listen to the R4 ‘In Our Time’ 45 minute podcast available from http://www.bbc.co.uk/programmes/b00vcqcx With A.C. Grayling – Professor of Philosophy at Birkbeck, London; Peter Millican Gilbert Ryle Fellow in Philosophy at Hertford College, Oxford and Rosanna Keefe – Senior Lecturer in Philosophy at the University of Sheffield.
304 pages in the Penguin 2nd revised edition paperback
Originally published 1977.
ISBN 978-0141003146
Wilfrid Hodges