Understanding hypothetical propositions is very important for both deductive and inductive logic, because they are actually quite complex constructs with many significant details. Do read chapter 24 of FL and indeed the chapters before and after it (23 and 25). (It is also important to know that these concern only logical conditioning, and that de re conditioning has significant differences.)
The difference between material and so-called strict implication lies, as you read, in the modality of the definition of "If P then Q". Authentic implication is that "P without Q is IMPOSSIBLE", whereas the modern logicians' ersatz version that "P without Q is FALSE" is really not implication but simply negation of conjunction. That is why the modern version does not in fact have a negative hypothetical "If P not-then Q" (for this would merely amount to the positive conjunction "P and notQ is true"), whereas the authentic version provides a form for the negation of implication, NOT(if P then Q), which is colloquially said "If P NOT-then Q" (or more wordily, "Given P, it does NOT follow that Q"). This is of course a very important form, as you can see if you read The Logic of Causation" one day.
Something about you (optional) Logician, philosopher
Thanks again. I've recently purchased a copy of FL and will open a thread here in due course so that I can post any queries that come up as I read it (there are bound to be some).
I'm a little disappointed that the book has no index, although the TOC is quite comprehensive.
Hi Greg. Good for you! I hope you got a hardcopy rather than an e-book. It is a big book, best read on paper.
As regards an index, it is a massive very difficult job. I have not to date found software able to help me. A professional is very expensive and anyway he would have to know the subject pretty well to pick the right words.
If you need to find something you can always use the search facility in thelogician.net (you can zero in on FL specifically instead of the whole site).
Something about you (optional) Logician, philosopher
Yes I have a hardcopy of FL. There are quite a few software packages to help with generating an index, but you're right it's not just a matter of point-and-click.
Good, Greg. My recommendation is read/study a chapter a day, or even a section or page a day if you prefer. This is how I study, and I get through very thick books that way. It is surprising how quickly time passes, and then one is halfway through the book or at the end of it.
Do tell me of any book Indexing software you know about.
Something about you (optional) Logician, philosopher
