NicholasW wrote: The example quoted in Chambers is that No smoking abaft the funnel implies that smoking is allowed before the funnel.
This seems to get us back to the first post in this thread - wouldn't assuming that one could smoke before the funnel be begging the question?
This example also leaves me puzzled. In this example, there seems to be a proscriptive rule, rather than a rule based on standard practice or theory. In other words, "the rule says no" vs. "as I rule I do this" or even the Laws of Thermodynamics as a rule based on observation of the behavior of things. This is not how I had understood this phrase to be used. I understood it to mean that, based on observation, one might derive a rule for the behavior of something (e.g, every day my cat gets up and scratches at the door frame and I rush to open the door before he does further damage to the wood) or the example of earlier "as a rule, I cross at a green light" and that somehow an exception to this rule would prove it. Because of this understanding I was (briefly) very pleased to hear about the other, older meaning of "prove" as "to test" - it made a nice logical package.
Now I must ask - in this saying, are we talking about a rule that dictates behavior (e.g. No Smoking) or a standard practice ("as a rule") or a theory based on observation?
What's the rule here?
