Could the Philistines write? Of course they could. They must have been able to write. The question arises because we can’t produce a single specimen that can be identified positively as Philistine writing. We don’t even know what language the Philistines spoke.
We know the Philistines could write because writing was well-known in the ancient world and the Philistines were a great ancient civilization.
Many large caches of ancient texts have been found by archaeologists, and occasional inscriptions are continually uncovered in excavations. Scholars have identified and translated texts in Sumerian, Akkadian, Babylonian, Egyptian, Ugaritic, Hittite, Hebrew, Moabite, Aramaic and Greek, just to name some of the best known Near Eastern languages—but not Philistine.
The absence of Philistine inscriptions is especially anomalous because we know so much about the Philistines, not only from the Bible, but from innumerable excavations where they left their remains and from the walls of Egyptian temples where they are depicted.
In 1964 some clay tablets inscribed in a linear script were found by Professor H. J. Franken at Deir Alla in the Transjordan. Some scholars have suggested that the script is Philistine. The tablets were found in association with Philistine pottery. In 1968–1969, Professor Moshe Dothan, digging at Ashdod, uncovered two inscribed seals from strata XIII–XII, again associated with the Philistines, which he dated to 1700–1150 B.C. This script is otherwise unknown, but it resembles the Deir Alla script. It may well be written in the Philistine script, but it, like the Deir Alla tablets, is still undeciphered. Both the Deir Alla and the Ashdod scripts are apparently related to the linear scripts utilized in the Aegean Basin throughout the Late Bronze Age, i.e., Linear A and B and the Cypro-Minoan syllabary, and as such add still another independent source pointing to the Aegean as the Philistine homeland.