1. to think through something logically and methodically, considering all relevant factors with deliberation and attention to detail
You need to reason carefully before making such an important decision.
Você precisa raciocinar cuidadosamente antes de tomar uma decisão tão importante.
2. to engage in careful logical analysis or argumentation
The scientist had to reason carefully to arrive at the correct conclusion.
O cientista teve que raciocinar cuidadosamente para chegar à conclusão correta.