Although phenoxide ion has more number of resonating structures than carboxylate ion, carboxylic acid is a strong acid than phenol. Why ?

Explanation

Both aliphatic carboxylic acids (RCOOH) and phenol have a tendency to release protons as follows :

Both carboxylic ion and phenoxide ion are resonance stabilised as explained below.

Although phenoxide ion has more number of resonating structures (five) than carboxylate ion (two) yet carboxylate ion is better resonance stabilised than phenoxide ion. It is due to the following two facts :
(i) The two contributing structure of carboxylate ion are structurally equivalent, whereas it is not so in case of phenoxide ion.
(ii) In carboxylate ion the negative charge in dispersed over two oxygen atoms, whereas in phenoxide ion, in four out of six resonance structures the negative charge is on less electronegative caron atom.
Due to bettwe resonance stabilisation of carboxylate ion the equilibrium is shifted more towards the right hand side in case of carboxylic acid than in phenol. Thus we can say that carboxylic acids have a greater tendency to release the proton or in other words carboxylic acid is more acidic than phenol.