loseyourname said:
It is not disputable that it is valid. The conclusion itself most certainly is. If one or more premises is false, if any premise is inconsistent with another premise, or if the argument is circular, then nothing is established.
Oops, thanks. I should have said the conclusion of a valid deductive argument is true if the premises are all true.
How would an argument with inconsistent premises be valid?
The reason I brought this up was to suggest deduction be moved to the "Fact" row.
Fredrick said:
If you mention that only statements can be considered facts, what would be an example: make it as common as possible. I am looking for an example where there is no discussion possible, like with the color blue.
I'm not sure how far you want to go with this, and I'm certainly not the most qualified to help you. I'll take a shot, and you and others can check me. Read
https://www.physicsforums.com/showpost.php?p=390664&postcount=6 for a good explanation of factually meaningless statements.
If you want everyone to know your statement is true, you are asking for a lot. When you claim that a statement is true, you are really claiming the statement is true in some system, according to a set of rules and definitions. When you say "All trees are blue", you are implicitly claiming "All trees are blue" is true in some system where all of the terms and rules for relating the terms in the statement are defined. And a statement like "All trees are blue" is claiming even more, by using "all".
The statement you're asking for is equivalent to "All people will know this statement is true." That's quite a statement! Of course, you can safely assume some things will be known by most people. Most people know their name, have seen the color blue, etc.
The color blue is actually an interesting example because even someone who hasn't seen blue (ex. if they have been blind from birth) has almost certainly experienced other things described by the physical sciences (felt the warmth of the sun, for example). You could possibly use those experiences to prove statements about the color blue to them, since colors are described by the physical sciences.
Anyway, you are safe using colors as an example as long as you remember to pair your statements with their systems. If your audience knows what a color book is and will agree to use it as a definition of blue, you're fine. I think I've rambled a bit. If I haven't answered your question, just ask again.