I'm reading Peter Geach's Good and Evil, and am struggling to understand what predicative and attributive adjectives mean, the significance of the words and how they be applied to good and bad.
See examples at the very beginning of Geach's essay (1956).
It is a grammatical distinction: a "small elephant" is not something that is an elephant and is small because elephants are big (speaking absolutely). A small elephant is small only relative to the elephants kind.
Peter Geach (1956) argues that G.E.Moore [in Principia Ethica (1903) and elsewhere, Moore embraces the consequentialist view that whether an action is morally right or wrong turns exclusively on whether its consequences are intrinsically better than those of its alternatives] makes a serious mistake when comparing “good” with “yellow.” Moore says that both terms express unanalyzable concepts but are to be distinguished in that, whereas the latter refers to a natural property, the former refers to a nonnatural one. Geach contends that there is a mistaken assimilation underlying Moore’s remarks, since “good” in fact operates in a way quite unlike that of “yellow”—something that Moore wholly overlooks.
This contention would appear to be confirmed by the observation that the phrase “x is a yellow bird” splits up logically (as Geach puts it) into the phrase “x is a bird and x is yellow,” whereas the phrase “x is a good singer” does not split up in the same way. Also, from “x is a yellow bird” and “a bird is an animal” we do not hesitate to infer “x is a yellow animal,” whereas no similar inference seems warranted in the case of “x is a good singer” and “a singer is a person.”
On the basis of these observations Geach concludes that nothing can be good in the free-standing way that Moore alleges; rather, whatever is good is good relative to a certain kind.
Just an add-on to Mauro's answer. Left to myself I'd say that 'predicative'/ 'attributive' is both a linguistic and a logical distinction:
Predicative and attributive
For Geach ...surface grammar is no sure guide to the attributive/predicative distinction. He says, I shall say that in a phrase 'an AB' ('A' being an adjective and 'B' being a noun) 'A' is a (logically) predicative adjective if the predication 'is an AB' splits up logically into a pair of predications 'is a B' and 'is A'; otherwise I shall say that 'A' is a (logically) attributive adjective (op. cit., p. 33). 'Big', 'small', 'forged' and 'putative' are his examples of logically attributive adjectives since 'x is a big flea' does not split up logically into 'x is a flea' and 'x is big', 'x is a small elephant' does not split up logically into 'x is an elephant' and 'x is small', 'x is a forged banknote' does not split up logically into 'x is a banknote' and 'x is forged', and 'x is the putative father of y' does not split up logically into 'x is the father of y' and 'x is putative'. 'Red' and 'sweet' are his examples of logically predicative adjectives since 'x is a red book' does split up logically into 'x is a book' and 'x is red', and, presumably, 'x is a sweet apple' does split up logically into 'x is an apple' and 'x is sweet'. Thus although 'small' in 'Dumbo is small' is grammatically predicative, it is logically attributive, and although 'red' in 'x is a red book' is grammatically attributive, it is logically predicative. (Alfred F. MacKay, 'Attributive-Predicative', Analysis, Vol. 30, No. 4 (Mar., 1970), pp. 113-120: 115; references to Geach are to P. T. Geach, 'Good and Evil', ANALYSIS, Vol. 17, December, 1956, pp. 33-4.)
Geach tries to show that 'good' is always an attributive adjective:
For 'good' the point is not so clear at first sight, since 'good' is not alienans [GT - see below] - whatever holds true of an A as such holds true of a good A. But consider the contrast in such a pair of phrases as 'red car' and 'good car'. I could ascertain that a distant object is a red car because I can see it is red and a keener-sighted but colour-blind friend can see it is a car; there is no such possibility of ascertaining that a thing is a good car by pooling independent information that it is good and that it is a car. This sort of example shows that 'good' like 'bad' is essentially an attributive adjective (op. cit., pp. 33-4).
There is no space to discuss the point here.
'Putative' in 'putative father' is alienans, since a 'putative father' is not both a father and putative. Indeed the point of the 'putative' is that he may not be a father at all. (Charles R. Pigden, Geach on 'Good', The Philosophical Quarterly (1950-), Vol. 40, No. 159 (Apr., 1990), pp. 129-154: 131.)