Hazards of propositional logic
**Hazards of propositional logic**

Scientists use propositional logic sparingly because it's extremely sensitive to **misleading premises**.

**Classic example of propositional logic:**
"Horses have an even number of legs. In the back they have two legs, and in front they have fore-legs. This makes six legs, which is an odd number of legs for a horse to have. But the only number that is both even and odd is infinity. Therefore, each horse has an infinite number of legs."

**Critics of evolution often employ propositional logic. For example:****
****"Evolution is false because intermediate fossils are missing."**

This is a conjunction of three propositions:

1- Evolution requires intermediates

2- There should be fossils of these intermediates

3- These fossils should have been found

Proposition 1 is generally true. Proposition 2 is not always true. Proposition 3 is not always true.

**Another example:****
****"Life is too complicated to have evolved"**

This involves two propositions:
1- Life is complicated

2- Complicated things can't arise by evolution

In this case proposition 1 is true. Proposition 2 is consistent with everyday experience, but not universally true.

**Another example:****
****"Radioactive dating is unreliable"**

This is a conjunction of:
1- Objects can be dated by radioactive methods

2- Some radioactive dates are preposterous

Proposition 1 is true. Proposition 2 assumes that the radioactive measurements satisfy the conditions necessary for accurate dating. Where measurements are preposterous they in fact don't satisfy the conditions for reasons that are usually obvious.

**One more example:****
****"Alternatives to evolution should be discussed in science class"**

This statement includes propositions:
1- There are alternatives to evolution

2- These alternatives are scientific

Here proposition 1 is true and proposition 2 is false

**Dubious premises make propositional logic a minefield. Scientists employ it cautiously. Abusing propositional logic is a standard rhetorical "trick". Uncritical use of propositional logic degrades critical thinking skills.**

The Discovery Institute is notorious for employing false premises.