Philosophy EthicsYou Can't Get an 'Ought' From an 'Is' Alone
Philo stands at a chalkboard in a cozy study lined with books, drawing two columns labeled IS and OUGHT, pointing to a gap between them with a piece of chalk while a curious student leans forward at a wooden desk.
- Explain the difference between a fact (descriptive) claim and a moral (normative) claim using your own words.
- Identify whether a given statement is a fact claim or a moral claim.
- Explain why a moral conclusion cannot follow from facts alone without at least one moral starting point.
- Select a correctly constructed argument that bridges a fact and a moral premise to reach a moral conclusion.
Key terms
- descriptive claim
- a statement about how the world actually is, which can be checked against evidence
- normative claim
- a statement about how things ought to be, what is right, wrong, or required
- is-ought gap
- the principle that a moral conclusion cannot follow from purely factual premises alone
- premise
- a starting claim that an argument relies on to build toward its conclusion
Where the Smuggling Happens
The is-ought gap matters because arguments often hide a moral assumption inside an innocent-sounding word. Calling a behavior 'natural,' 'normal,' or 'what everyone does' quietly imports a value — that natural or common things are good — without ever defending it. Once you learn to spot these loaded words, you can ask the arguer to state the hidden moral premise out loud. Often that premise turns out to be false or controversial, which is exactly why it was buried rather than stated.
The Bridge Rule
The reliable pattern is simple: facts combined with facts only give you more facts, while a moral conclusion requires at least one moral premise in the mix. A well-built moral argument states both pieces openly — one factual premise describing the situation and one normative premise about what matters — so the reader can examine each. Facts remain essential as evidence; they tell you what is at stake. But they cannot, by themselves, tell you what you ought to do about it.
Worked examples
Find the missing premise in: 'Lions kill prey, so hunting for sport is fine.'
- Identify the factual premise: 'Lions kill prey.'
- Identify the conclusion: 'Hunting for sport is fine,' which is a moral claim.
- Notice no moral premise connects the two, so a hidden assumption must be doing the work.
- Surface the hidden premise: 'Whatever animals do in nature is morally acceptable for humans,' then ask whether that is actually true.
Answer: The argument leaps from an is to an ought by smuggling in an unstated and questionable moral premise; once that premise is exposed and challenged, the conclusion no longer follows from the fact alone.
Activity
Sort each card into the IS column (fact claim) or the OUGHT column (moral claim). Then, on the back of one pair, try writing a single sentence that uses both cards together as premises to reach a moral conclusion.
Practice
Decide whether 'Most teenagers stay up past midnight' is a descriptive or normative claim, and explain how you know.
Write a sound argument that pairs one factual premise with one moral premise to reach a moral conclusion.
Common mistakes to avoid
- Facts alone can prove a moral claimA moral conclusion always requires at least one moral premise; facts supply evidence but cannot bridge to an ought by themselves.
- Whatever is natural must be morally goodCalling something natural is a factual description that smuggles in an undefended value; nature does not settle what humans ought to do.
Check your understanding
Which of the following is a moral (normative) claim?
Someone argues: 'Cheetahs are the fastest land animals, so speed must be the most important quality a person can have.' What is wrong with this argument?
Which argument correctly bridges a fact and a moral premise to reach a moral conclusion?
Recap
A fact claim describes how the world is and can be checked against evidence, while a moral claim says how things ought to be. Because of the is-ought gap, you always need at least one moral premise before facts can reach a moral conclusion.
Reflect
Where have you seen an argument leap from an 'is' to an 'ought'?