I found this paragraph in Parfit's On What Matters.

Some claims seem to be substantive, but are merely concealed tautologies, which everyone could accept whatever else they believe. Several Subjectivists use the words ‘reason’, ‘should’, and ‘ought’ in subjectivist senses. These people’s theories do not make substantive claims.

Perhaps substantive means 'non-tautological'.

---EDIT----

Just found this in On What Matters:

There is another way in which some people have come to accept subjective theories about reasons. We can call some normative claim substantive when this claim both

(a) states that something has some normative property, and

(b) is significant, by being a claim with which we might disagree, or which might be informative, by telling us something that we didn’t already know.

I found a paragraph in Parfit's On What Matters that gives a definition of "substantive normative claim":

There is another way in which some people have come to accept subjective theories about reasons. We can call some normative claim substantive when this claim both

(a) states that something has some normative property, and

(b) is significant, by being a claim with which we might disagree, or which might be informative, by telling us something that we didn’t already know. (p. 70)

I found this paragraph in Parfit's On What Matters.

Some claims seem to be substantive, but are merely concealed tautologies, which everyone could accept whatever else they believe. Several Subjectivists use the words ‘reason’, ‘should’, and ‘ought’ in subjectivist senses. These people’s theories do not make substantive claims.

Perhaps substantive means 'non-tautological'.

I found this paragraph in Parfit's On What Matters.

Some claims seem to be substantive, but are merely concealed tautologies, which everyone could accept whatever else they believe. Several Subjectivists use the words ‘reason’, ‘should’, and ‘ought’ in subjectivist senses. These people’s theories do not make substantive claims.

Perhaps substantive means 'non-tautological'.

---EDIT----

Just found this in On What Matters:

There is another way in which some people have come to accept subjective theories about reasons. We can call some normative claim substantive when this claim both

(a) states that something has some normative property, and

(b) is significant, by being a claim with which we might disagree, or which might be informative, by telling us something that we didn’t already know.