"Soft in head" is a colloquial expression used to describe someone who is not thinking rationally or acting logically. It is often used in a derogatory way to insult someone's intelligence or decision-making abilities. However, there are many synonyms that can be used to convey the same meaning without resorting to such an offensive phrase. Some examples include "mentally deficient," "scatterbrained," "airheaded," "dim-witted," "confused," "dopey," and "foolish." Using these terms instead of "soft in head" can help keep the conversation civil and respectful, and avoid offending anyone unnecessarily.