Source: pp 282-283, Think: A Compelling Introduction to Philosophy (1 ed, 1999) by Simon Blackburn
However, there is an issue here that divides thinkers into two camps. Consider this equation:
[1.] One of X's concerns is to aim for or promote or endorse Φ.
= [2.] X thinks Φ is: good or a reason for action. [I modified the syntax of 1 and 2.]
The division lies between thinkers who read this equation "left to right", and those who read it "right to left". That is, there are thinkers who suppose that the right direction of explanation is from concerns, taken as understood, to "seeing something as a reason", which is thereby explained. And there are those who think the right direction of explanation is from thinking that something is a reason, considered as a pure belief about the case, to concerns, which are thereby explained.
The difference is sometimes called that between "non-cognitivism" and "cognitivism" in the theory of ethics. The idea is that if the equation is read left to right, then talk of something being good, or something being a reason for action, is a kind of reflection of a motivational state of mind: the fact of something weighing with you.
[3.] This motivational state of mind is not a simple belief.
It is not a representation of some aspect of the world. It is a REACTION to representations of the facts of the matter.
[4.] It does not itself pick out some fact of the matter.
Hence it is not strictly speaking a state of mind that is either true or false, any more than a desire for coffee is either true or false. The noncognitivist direction is beautifully expressed by St Augustine:
[T]here is the pull of the will and of love, wherein appears the worth of everything to be sought, or to be avoided, to be esteemed of greater or less value.
How is this true? How can you be motivated by Φ, but not believe in Φ?
How does NOT a motivational statement of mind 'pick out some fact of the matter'? Anything on Earth (eg: Φ) is imperfect and must have pros and cons. So you must have picked the pros, over the cons, of Φ before Φ succeeded in motivating you.