The Cratylus dialogue revolves around the meaning of words and whether they are decided by convention or if they have a natural independent of people. Hermogenes and Cratylus respectively holds these positions and each have to cede to the opposite view in dialogue with Socrates.

Hermogenes position is that names decided by convention and that a thing can have as many names as people call it by. This communication by consensus is compared to the philosophy of Protagoras and Euthydemus. In Plato's interpretation Protagoras held that no objective truth existed and everyones perception was correct. Euthydemus is explained as holding that all things hold opposite properties in order to explain differing experiences. These viewpoints are rejected, objects must have properties independent of our perception.

Actions, in order to be succesful, must be in accordance with the properties of what they act upon. You can only cut a tree with a saw for example, recognizing the hardness of the tree with the sharpness of the saw's teeth. Not recognizing these properties would make the action impossible. Naming as an action must then adhere to the principles of the thing it names or else fail at communication. In a typical fashion of Plato's dialogues, Socrates asks Hermogenes for what the best tool is for a purpose and who uses it. E.g hammers are used by blacksmiths, but they are used by carpenters for construction and only they can judge its quality, not the maker. Naming is the act of dividing things according to their nature, their users are dialecticians and they makers must be rule-setters (not consensus). Makers use produce things to imitate the forms. Different makers can use different materials that will still be the same thing in imitation of the forms. This explains why there can be words spelled differently or synonyms.

When discussing the correctness of words Socrates brings up, as usual, comparisons to the works of Homer. In the Illiad gods and men have different names for the same things. The names by the gods must be correct. For a name to be correct it must reflect the nature of a thing, Hector's name means possessor and his son's name Astyanax means lord. But Socrates says there are exceptions, that "monsters" can be born without the nature of their progenitors. This can be why Cratylus says Hermogenes name is not his own. A major part of the dialogue is dedicated to finding the etymologies of words by Socrates. This can be seen as an example of the superior skill of the philosopher to employ any practice as in many dialogues like Menexenus. The etymologies were seen as legitimate in their day but do not live up to our contemporary standards. Words can be spelled differently but still have the same significance, as explained earlier with the makers using different materials to produce the same thing. As long as they express the essence of their object, and some words must be better at expressing the properties of this essence than others. Some words are actually phrases that have been corrupted to a single word. Others are foreign loan words. Many have become so mutated that they cannot be traced back to their origin. Primary words are those that do not originate in other words.

Eventually Socrates makes a discovery in Heraclitus, Homer, Hesiod and Orpheus both having the gods originate from ever changing waters. The idea that everything is in a permanent of change originates with Heraclitus, who Cratylus is a follower of. The original primary names were made by ancient wise men and since many of their origins is of motion, it suggests that everlasting change, becoming, is the nature of things.

Speech and writing is different from the imitiation of sounds in music. Speech attempts to imitate the properties of a thing, not the sound of it which is another craft, such as music. The words we use are only approximations, only the gods know the true names of things. Our perception of things is always changing, but is the nature of things also always changing as the Heracliteans would claim?

Cratylus holds the naturalist position that names have a natural origin independent of people. Names reflect the properties of things and are not a common agreement between people but are fundamental to the things they refer to. In fact, Cratylus does not even admit the possibility of misnaming. Words are likened to numbers where you for example you cannot call "one" anything but "one", because anything else would just be another number! Cratylus claims that Hermogenes's name is not his own and that he in fact does not know his own name, but Cratylus refuses to elaborate on it. When Cratylus is asked what he interprets of people using the wrong name for a person he calls it simply noise. But when he is confronted that he accepts words with slight differences in spelling or pronounciation, he says he still understands the significance because of "usage", which does not seem very far from convention! Opposite from Hermogenes, Cratylus has to cede that words are not perfect but approximations of the things they refer to. The nature of words from the Hermogenes discussion is reiterated: naming is a skill by rule-setters, and as skills of practitioners vary there must be better and worse names. The quality of names depends on how well they reflect the properties of the thing they refer to. But a name cannot be possibly reflect all qualities of a thing, then the name would be indistinguishable from the thing! Thus names are like images, inherently imperfect.

During the discussion it is discovered that the roots of words are in the consonants which reflect the properties of the thing the names refer to. But there is a problem, some etymologies are found to lie in stillness while some are in motion. The true nature of things cannot be both, it ought to be either or.

The dialogue ends with a discussion on how knowledge could be possible if everything is in permanent change as Heraclitus says. If one learns the nature of a thing in one moment, it will have changed in the next and one would no longer possess knowledge of it, almost like Zeno's paradox of motion. Can "knowledge" even exist if "knowledge" itself is always changing? Cratylus holds to the Heraclitean viewpoint and the nature of epistemology rests unsolved.

Overall the dialoague shows how Plato's synthesis of being and becoming approaches names, both extreme positions are reconcilled within the framework.

Notes: Cratylus is thought to have been a real person and the one who introduced Plato to the philosophy of Heraclitus.

Hermogenes is the brother of Callias, which has paid lots of sophists for wisdom and has gained a reputation for being wise. He appears in other dialogues.

Socrates posits that children inherit the names of their parents like with Hector and Astyanax. But he makes an exception for when "monsters are born". I'm a bit confounded as to what Plato means with this. That something can give birth to a thing not of its own nature, which might be horrific?

I think Hermogenes should not have cedeed so easily that communication is imitation of things. Naming by convention could be formulated as not making names resembling things but instead as working on the mind(s) of the subject. People have imperfect and divergent understandings of things and names work to bridge these differences between minds. Of course this would be unacceptable to Plato as this framework is inherently imperfect and nowhere near true knowledge of things.

In one passage Socrates explains that since desire is the strongest of any force, that must be what Hades uses to forever hold souls in his domain. There is no desire stronger than company with one that will better you. Hades is jokingly (?) refered to as a perfect sophist, but also a philosopher. It is only when souls are free from material influnce that he convinces them to embrace virtue with him. Is this just a humorous speculation? The souls in Hades do not seem very cheerful or virtous in the Oddysee for example, and Plato rarely contradicts Homer.