logical
adjective
ˈlɒdʒɪkl 
ˈlɑːdʒɪkl 
1 (of an action, event, etc.) seeming natural, reasonable or sensiblea logical thing to do in the circumstancesIt was a logical conclusion from the child's point of view.Each of them having their own room was the logical solution.2 following or able to follow the rules of logic in which ideas or facts are based on other true ideas or factsa logical argumentComputer programming needs someone with a logical mind.Opposite
illogicallogically ˈlɒdʒɪkli ˈlɑːdʒɪkli 