It is true that one has to be careful about facts in history. Indeed, generally speaking, the further back you go, the more difficult it is to find facts - so us guys in Ancient Greece have to be a little cautious.
But some things are facts and I'll present a little info/evidence for those who are concerned with getting their facts straight rather than resting in not-knowing, because although this is 'only' a game site, I see no reason why precision and detail do not sometimes have their place, at least for those who wish it.
ASPIS/HOPLON
The aspis/hoplon ‘debate’ is one of those rare things in that is in fact not ambiguous at all. There is a correct answer to the debate, and there is evidence (lots of it) to support the correct view. The incorrect view has no leg to stand on, despite its amazingly widespread support, and has no evidence backing it up. A rare bird indeed.
Anyone who can read Greek and peruses Herodotus, Xenophon and Thucydides (and various other chaps who actually fought in Classical Greece and wrote about it) will see immediately that hoplon doesn't even mean shield (never mind a particular one). It means arms/weapons (sometimes tools). The word aspis in reference to a hoplite’s shield occurs fifty times in Xenophon and more than ten times in Thucydides’ Peloponnesian War. Hoplon is not used at all specifically for shield in these works.
Here are just a few random examples from the original Greek text from Thucydides (translations by Richard Crawley) showing that the Greek word for a shield carried by a hoplite is an aspis (I'm guessing the majority do not read Classical Greek, but if you even just look at the context of the quotes you can see what I'm saying):
...hoi de akousantes parêkan tas ASPIDAS hoi pleistoi kai tas cheiras aneseisan... [4.38.1]
[The Lakedaimonians (hoplites)]...hearing this offer, most of them lowered their shields and waved their hands...
...ep' ASPIDAS de pente men kai eikosi Thêbaioi etaxanto... [4.93.1]
...The Thebans [hoplites] formed twenty-five shields deep...
...to de allo karterai machêi kai ôthismôi ASPIDON xuneistêkei... [4.96.2]
...the rest [of the hoplites]engaged with the utmost obstinacy, shield against shield...
And a few to show that the word hoplon is used to mean 'arms' in a general sense:
...kai xunêthê tên diaitan meth' HOPLON epoiêsanto hôsper hoi barbaroi. [1.6.1]
...indeed, to wear arms was as much a part of everyday life with them as with the barbarians.
...gnôsthentes têi te skeuêi tôn HOPLON xuntethammenêi... [1.8.1]
...they were identified by the fashion of the arms buried with them...
...eisi gar kai ekeinois ouk elassous chrêmata pherontes xummachoi, kai estin ho polemos ouch HOPLON to pleon alla dapanês... [1.53.2]
...have allies as numerous as our own, and allies that pay tribute, and war is a matter not so much of arms as of money...
Diodorus is much to blame for the confusion, because it is he who said the peltast and the hoplite are named after their shields (and we know for a fact that pelte is used for light shields in the ancient texts). In fact, he can be disregarded regarding many military details, and he's not a primary source - you have to remember he wrote four centuries after the Peloponnesian War.
What he actually says is that the hoplite is named after his shield - and in a sense he is, because hoplite means heavily-armed, and in those days the aspis was the heaviest piece of equipment a soldier might carry, weighing about 15 lbs.
Indeed, for much of the period the large shield was the only thing that distinguished the hoplite's equipment from other troops - thus he carried a heavy shield and was called a heavy infantryman - thus he was named after his shield.
But anyway so much of what Diodorus says conflicts with what people who were there at the time say about war. Far better to read the texts of the men who actually carried the shield during Classical Greece.
And it’s not just the military historians. Aristophanes, the comic playwright, who lived and wrote during the Peloponnesian War, mentions ‘shield’ eight times in Acharnanians, once in Birds, twice in Clouds – all are aspis. There are many other instances of this in the ancient literature.
It’s true that Liddell and Scots Greek Lexicon (from the 1800s!), still the most widely used Attic dictionary, bought into the hoplon myth, but if you look up hoplon in the much more recent Oxford Classical Greek Dictionary, you'll see yet more evidence:
“Hoplon (ou to) usu. pl.: Tool, implement; ship’s tackle; arms, harness, armour, weapon; camp.”
No mention whatsoever of shields.
The fact is the word 'hoplite' is an old word (from at least the writer Pindar, probably before), and when hoplites began their career they were indeed heavily-armed - a thick bronze cuirass (this is before the linothrax etc.), greaves, a large, closed helm, and often leg and arm (even foot) armour. So it seems likely the hoplite was named for his overall panoply. (And it is pan(H)OPLy, as in 'all-arms').
Basically, if you go through the entire corpus of Greek Classical literature, you will find the word used for hoplite shield is aspis, and that hoplon doesn’t mean shield (except occasionally where it’s a shield as part of 'arms and armour').
Belief in the hoplon is still widespread. Since the 80s a few of us have debated this (and received much abuse for doing so!) and in 1996 we finally got: 'The Myth of the Hoplite's Hoplon' by Lazenby and Whitehead in Classical Quarterly Vol. 46. The title says it all.
But the myth persists, simply because people build on others' mistakes and rarely take the time to really find out (after all, we're all so busy...).