Wireless Philosophy - CRITICAL THINKING - Fundamentals: Introduction to Critical Thinking [HD]

Short Summary

Main recommendation: Critical thinking means making sure you have good reasons for your beliefs, where a good reason is one that makes the belief probable or likely to be true, and the best reasons guarantee it. The lesson teaches this by evaluating arguments, distinguishing premises from conclusions, and separating deductive arguments (premises guarantee the conclusion) from ampliative arguments (premises make the conclusion probable but do not guarantee it).

Key Points

• Rational people want true beliefs and avoid false ones, and the best way to pursue that is to form beliefs only when good reasons support them.
• Goodness of a reason is about truth and probability, not morality; a reason is good if it makes the belief likely to be true.
• An argument is a set of premises that together give reason for a conclusion, and a good argument is one whose premises support its conclusion.
• A reason that is irrelevant to the conclusion (e.g., "I can't stand him, and I want to have a good time" for "Monty won't be at the party") does not support it, though it could become a good argument with an added background premise.
• Whether an argument is deductive or ampliative determines how it should be evaluated: a supposedly deductive argument whose conclusion can be false despite true premises is usually a bad argument, while objecting to an ampliative argument on the grounds that its conclusion could be false misses the point.

Details Worth Noting

• Concrete instructions: When evaluating a claim, ask the person why they believe it, then sort their answers into good reasons (ones that make the claim probable or guarantee it) and bad reasons (ones unrelated to the claim). For an argument, identify the premises and conclusion, check whether the premises make the conclusion probable, and first determine whether it is meant to be deductive or ampliative before judging it. Reject a supposedly deductive argument if the premises could be true while the conclusion is false.
• In the lesson's example, "He's in Beijing, and it's impossible to get here from Beijing in an afternoon" guarantees Monty won't attend, while "He's really shy and rarely goes to parties" only makes it probable.
• A deductive argument's conclusion must be true if the premises are true; an ampliative argument's conclusion may still be false even when the premises are true, though it is unlikely.
• The lesson notes that a bad argument can be improved by adding a background premise, such as learning that the friend controls the guest list.
• Later lessons promise more tools for evaluating both deductive and ampliative arguments.

Bottom Line

Judge beliefs by the quality of their supporting reasons, and judge arguments by first checking whether they claim to be deductive or ampliative, since that determines the standard they must meet.