You Think You're Right — But Can You Prove It?
A Fight at the Lunch Table
It starts with a disagreement. Your friend says the new school rule about phone bans is unfair. You think it makes sense. She fires off a list of reasons. You fire back. Voices rise. Someone slams a lunch tray.
But here’s a question neither of you stops to ask: Are either of your arguments actually any good?
Most people think “argument” means a heated fight. Philosophers use the word differently. For them, an argument is a set of reasons — called premises — offered to support a conclusion. The premises are the evidence. The conclusion is what you want someone to believe. Between them sits an inference: the mental leap from reasons to conclusion.
Take this everyday example: “You should try the new taco place because it uses fresh ingredients and the prices are reasonable.” The conclusion is “You should try the new taco place.” The premises are the fresh ingredients and reasonable prices. The word “because” is an inference indicator — a signpost that says “here come my reasons.”
Real-life arguments are rarely this tidy. People ramble. They leave things out. They mix good reasons with distractions. That’s where informal logic comes in.
Untangling the Mess
Real arguments are messy. People speak in rhetorical questions. (“Can anyone seriously believe that?”) They repeat themselves. They bury their main point under side stories. Sometimes they don’t even state their real reasons out loud.
Standardizing an argument means cleaning it up. You strip away the noise, clarify fuzzy claims, and lay out the premises and conclusion in a clear list. The goal isn’t to change what someone said — it’s to see the structure underneath.
Consider this comment from someone at a public meeting: “The minor penalties normally associated with misdemeanor convictions are not a sufficient deterrent in this case.” They’re arguing for a prison sentence. The explicit premise is clear: minor penalties don’t deter. But the argument relies on implicit premises — claims the speaker assumes without saying them. First, that penalties should deter people. Second, that prison is a sufficient deterrent. Without those hidden claims, the argument doesn’t hold together.
Implicit premises are everywhere. Ancient philosophers called arguments with hidden pieces enthymemes. A modern example: someone says, “A person who enters the country illegally is not a lawful combatant. They don’t deserve prisoner-of-war treatment.” The unstated bridge is: “Someone who is not a lawful combatant doesn’t deserve that treatment.” That hidden claim does the heavy lifting.
When you standardize an argument, you have to decide how to interpret those missing pieces. Philosophers often follow the Principle of Charity: choose the interpretation that makes the argument as strong as possible. If you can read someone’s argument in two ways — one clever and one ridiculous — you test the clever version. That way you engage with the best version of what they might mean, not a straw man you can easily knock down.
The Test: Is It a Good Argument?
So you’ve standardized an argument. You can see its bones. Now the real question: is it any good?
Informal logicians generally agree on two big requirements. A good argument needs acceptable premises and a valid inference. If the premises are shaky or the conclusion doesn’t actually follow from them, the argument fails.
Think of it like building a tower. Acceptable premises are solid bricks. A valid inference is a strong connection between them. If your bricks are made of sand, or if they don’t actually support the floor above, your tower won’t stand.
What makes a premise acceptable? Often, it needs to be true — or likely true. But truth isn’t always the standard. In a courtroom, premises must follow rules of evidence. In a bargaining session, a claim like “I won’t pay more than three hundred dollars” can be acceptable even if it’s an empty threat — because that’s how bargaining works. In other situations, premises need only be plausible or widely accepted.
What about validity? In formal logic, a deductively valid argument is one where the conclusion must be true if the premises are true. But real arguments rarely lock into place that tightly. Many are inductive: the premises make the conclusion probable but not guaranteed. (“Every French person I’ve met has been stylish, so French people are generally stylish.”) Others are conductive: you pile up reasons that aren’t decisive alone but together make a strong case — like clues pointing to a suspect. Still others are abductive: you reason backward to the best explanation. (“The sidewalk is wet, so it probably rained.”)
Some informal logicians boil the test down to three questions you can ask about any argument’s premises: Are they Acceptable? Are they Relevant to the conclusion? And are they Sufficient to make the conclusion worth believing? These are the ARS criteria — a quick checklist for everyday reasoning.
Traps, Shortcuts, and Real Reasoning
When arguments go wrong, they often fall into predictable patterns. Philosophers call these patterns fallacies. You’ve probably heard of some: ad hominem (attacking the person instead of their argument), slippery slope reasoning, hasty generalization, begging the question.
For a long time, teaching informal logic meant teaching students to spot fallacies — sometimes hundreds of them. The idea was that if you could name the mistake, you could avoid it.
But there’s a problem. Many traditional fallacies have perfectly reasonable uses. Take ad hominem. If someone argues that a company should cut down a forest, and you discover they own shares in the logging company, pointing that out isn’t a fallacy — it’s a legitimate reason to question their motives. Or consider slippery slope reasoning: if a military intervention really would trigger a chain of disastrous consequences, that’s a good reason to oppose it.
This pushed informal logicians toward a different tool: argument schemes. A scheme is a pattern of reasoning that can be used well or badly. Take the scheme Argument from Authority: “An expert says X, so X is true.” This can be strong — if the expert is credible, speaking in their area of expertise, and backed by evidence. Or it can be weak — if you’re citing a celebrity to support a scientific claim.
Each scheme comes with critical questions you can ask. For Argument from Authority: How credible is the authority? Is this their domain of expertise? Do other experts agree? Is their claim based on evidence? These questions help you sort genuine expertise from bluffing.
Treating fallacies as misused schemes changes how you evaluate arguments. You stop asking “Is this a fallacy?” and start asking “Did they earn this conclusion, or are they taking a shortcut?”
Why This Matters to You
You live in a world flooded with arguments. Politicians claim their policies will save the country. Advertisements promise a new phone will transform your life. Social media overflows with hot takes and viral videos that mix evidence with emotion. Your friends argue about which team is better, which show is worth watching, whose turn it is to do the dishes.
Informal logic won’t tell you what to believe. But it gives you tools to think clearly about why you believe it.
That’s the heart of the Critical Thinking movement, which grew alongside informal logic in the 1960s and 1970s. Educators argued that schools should teach students not just facts, but how to scrutinize the reasoning behind claims. In 1980, California’s state university system made critical thinking a required part of the curriculum. The movement spread. Today, courses around the world teach students to standardize arguments, check premises, spot weak inferences, and ask the questions that separate good reasoning from noise.
The field keeps growing. Researchers now use computers to analyze huge collections of arguments — from legal documents to online debates — looking for patterns in how people actually reason. Artificial intelligence researchers build systems that can follow and evaluate arguments. Informal logic has become part of a broader field called argumentation theory, which brings together logic, rhetoric, psychology, and computer science to understand how humans argue and how we can argue better.
But you don’t need a textbook or a computer to start. The next time you’re in an argument — a real one, with someone you care about, over something that matters — try this: pause. Ask what your premises actually are. Ask whether they’re true. Ask whether they really support your conclusion. Ask whether you’re ignoring an important objection. Then do the same for the other person’s argument.
You might be surprised by what you find. You might even change your mind.
Think about it
- Think of a time you changed your mind about something important. What argument — from someone else or from your own thinking — actually convinced you? What made that argument work where others had failed?
- If a friend gives you three good reasons to do something and one obviously terrible reason, should the terrible reason make you doubt everything they said? Why or why not?
- Is it ever fair to judge an argument based on who is making it, rather than just looking at the reasons themselves? Give an example from your own experience.
