Direct opposites:
* Illogical: This is the most direct antonym, meaning lacking in logic or reason.
* Irrational: This implies a lack of reason or sound judgment.
Other possibilities depending on context:
* Emotional: If you're talking about a decision or argument, "emotional" could be the opposite of a logical one.
* Intuitive: This suggests relying on feeling or instinct rather than logic.
* Impulsive: This means acting without thinking or planning, which is the opposite of a logical approach.
* Unrealistic: If the context is about a plan or idea, "unrealistic" could be the opposite of a logical one.
* Abstract: If the context is about a concept or thought process, "abstract" might be the opposite of "logical" when the latter refers to concrete, tangible reasoning.
It's important to consider the specific context to choose the most fitting antonym.