1. Metaethics

2. Naturalism
Everything can be explained in terms of the things that occur in scientific theories of the world
In ethics, if moral claims are either true or false then there has to be something in the world which makes them T or F

3. Is/Ought
Hume
In every system of morality, …the author proceeds for some time in the ordinary way …; when of a sudden I am surpiz’d to find, that instead of the usual copulations of propositions, is and is not, I meet with no proposition that is not connected with an ought, or an ought not.

4. Is/Ought What does Hume’s argument show? What is Hume claiming?
Any domain of discourse is semantically sealed
What is Hume claiming?
Any domain of discourse is ontologically sealed

5. The Naturalistic Fallacy
Moore
Ethics aims at discovering what are those other properties belonging to all things which are good. But far too many philosophers have thought that when they named those other properties they were actually defining good; that these properties, in fact, were simply not ‘other,’ but absolutely and entirely the same with goodness.

6. The Naturalistic Fallacy
Arguments
The Open Question
Given any explanation of Good in terms of X you can always ask whether a thing which has X is really good.
Since the question makes sense, Good is not just having X
Objections
Water is H2O
Tautologies aren’t necessarily obvious to everyone

7. The Naturalistic Fallacy
Arguments
Unmotivated Morality
To be good is to have natural property P
Why am I motivated to do things with natural property P?
Objection
Haven’t found the motivator so far