Match the standard to the mode of reasoning
Before you judge an argument, identify what kind of support it is trying to provide. This lesson builds directly on Lesson 2: you learned that deductive arguments aim at necessity, inductive arguments aim at probability, and abductive arguments aim at the best explanation. Now you need to apply the corresponding evaluative standard to each mode. Deductive arguments are judged by validity: if the premises were true, would the conclusion have to be true? Inductive arguments are judged by strength: do the premises make the conclusion likely enough to accept? Abductive arguments are judged by explanatory quality: does the preferred hypothesis account for the evidence better than its rivals?
Using the wrong standard is one of the most common errors in argument evaluation, and it can make even careful analysis go wrong. Criticizing an inductive argument for not guaranteeing its conclusion is like criticizing a weather forecast for not being a mathematical proof — it misidentifies what the argument is trying to do. Similarly, praising a deductive argument for having strong evidence misses the point: deductive arguments succeed or fail on their form, not on the quantity of evidence.
Students often mis-evaluate arguments by jumping directly to whether they agree with the conclusion. That instinct is natural but misleading, because logic evaluates the support relationship between premises and conclusion, not personal belief. A persuasive conclusion can come from poor reasoning (you might believe something true for bad reasons), and an unpopular conclusion can follow from excellent reasoning (valid arguments with true premises sometimes lead to conclusions we would rather not accept). Your first obligation is to inspect the connection between premises and conclusion, not to vote on the conclusion itself.