Final answer:
The branch of philosophy focused on distinguishing between valid and invalid reasoning is called logic. It involves formalizing reasoning to assess the validity of claims and is fundamental to the philosophical methods used to discover truth, encompassing deductive and inductive reasoning.
Step-by-step explanation:
The branch of philosophy that seeks to distinguish between valid and invalid reasoning is known as logic. Logic is essentially the science of reasoning, seeking to formalize the reasoning process to assess the validity of claims and arguments. It helps us understand whether our claims are well-founded and consistent, or if they are the result of poorly constructed reasoning. Philosophers use logic to analyze and verify arguments, applying rigor to the process of thinking to approach the truth.
For example, the work of Gottfried Wilhelm Leibniz made a clear distinction between necessary truths of reasoning, such as the laws of noncontradiction and excluded middle, and contingent truths of fact based on experience. Logical reasoning encompasses different forms, including deductive reasoning and inductive reasoning, which philosophers utilize to develop philosophical methods to discover truth. Deductive reasoning starts from general principles to arrive at specific conclusions, whereas inductive reasoning accumulates specific examples to form a broad generalization.
Understanding argument structures is also vital in logic. A good deductive inference is considered a valid argument if its structure ensures that the truth of the premises guarantees the truth of the conclusion. This critical aspect of logic is integral for philosophical study and enables students to avoid common pitfalls of everyday thinking, like confirmation bias.