Learner's definition of LOGIC
1
a
:
a proper or reasonable way of thinking about or understanding something
[noncount]

If you just use a little logic, you'll see I'm right.

the rules of logic

There's no logic in/to your reasoning.

I can't see the logic in always worrying about the future. = Where's the logic in always worrying about the future?

There's some logic to/in what he says.

She kept the dog, against all logic, after it attacked her. [=her decision to keep the dog was not logical/sensible]

Her decision defies logic. [=her decision makes no sense; her decision is not logical]
[singular]
b
[noncount]
:
a particular way of thinking about something
2
[noncount]
:
the science that studies the formal processes used in thinking and reasoning
—
see also fuzzy logic
3
[noncount]
:
the way facts or events follow or relate to each other
4
[noncount]
technical
:
the arrangement of circuits in a computer