Aristotle's rules of deductive logic are how we define science as it

combines statements of the natural world to draw conclusions and inferences.

We can look at examples where deductive reasoning fails, and

it's important to look at these examples and see if you can see why they fail.

Sometimes deductive reasoning fails dramatically and

in an obvious way, and sometimes the failure is a little subtle.

Often when we miss the failure of logic,

it's because we don't question the premises.

Logic combines statements of the natural world, or

observations, or theories to draw a conclusion.

But if those premises or assumptions are faulty, or

not justified by data or observation, then the combination in logic fails.

Logic is just a tool.

It can't define the veracity of the statements that goes into it.

There are two fundamentally different kinds of logic that apply in science,

in any field of science, deductive and inductive logic.

Deduction is the theory put together by Aristotle and

burnished over the centuries since then.

An example of deductive logic involves arithmetic.

The statement, 2 plus 2 equals 4 is completely and self-consistently true.

It doesn't matter on your opinion,

your point of view, whether there's a y in the month, it's always true.

And in that way,

deductive logic always produces reliable conclusions, if the premises are valid.