re: #30 b_sharp

The syllogism;

is missing a condition, is it not?

Isn’t it necessary for P to be true if and only if Q is true?
In the above case, climate change can be true even if we should not regulate CO₂

yes - modus tollens is used fallaciously when the consequent, in this case “co2 should be regulated”, is a statement of something that should or might happen rather than what will happen or always happens. in this case, the if - then - relationship cannot be used in the same way as when the consequent is phrased as a statement of fact, as for example if you said “if global warming is true, al gore will lose 40 pounds by christmas 2011”. in this case, if al gore is still fat by christmas, you can legitimately deny the if clause, “global warming is true”