Rational thinking is the opposite of emotional thinking. Rational thinking is the opposite of emotional or biased thinking. You have certain conditionings and obsessions from childhood. You often think under their influence.  The other way is to leave aside your conditioning and think on the basis of facts. This is to think on the basis of facts by leaving aside all biases and emotions. This is rational thinking. I will give you an example. Once a person came to me and said that he gave a book of mine to a person in disagreement with me. Before giving the book, he removed my name from it. The person read the book and really liked it. He began to praise the book. When he was told that the book is by the author whom he was in disagreement with, he expressed great displeasure. This is an example of biased thinking. You have some biases about a person and assume that whatever he says is definitely wrong. The other way of thinking is one based on facts and realities. Basing an opinion on facts is rational thinking. Emotional thinking is thinking based on your biases and prejudices. Emotional thinking is the opposite of rational thinking.