The words sophism, sophist refer to very distinct realities in philosophy and in ordinary language.
1. The historical sophists
In Ancient Greece, the sophists were the first to implement a philosophy of language in their interactions with their fellow citizens. By means of calculated discursive interventions called “sophisms”, the sophists destabilize the peaceful current representations of the world as seen through language. They emphasize the “arbitrariness” of language (within the Saussurian meaning of “arbitrary”), and so provoke naive speakers who consider language to be transparent and unproblematic. These discourses are not intended to deceive their audience, but to highlight to them the paradoxes of their current talk.
In the Euthydemus, Plato stages Socrates deconstructing sophistical arguments, such as the following one. Dionysodorus is a sophist, Ctesippus his naive interlocutor:
[Dionysodorus:] — […] And your father turns out to be […] a dog.
— And so does yours, said Ctesippus.
— You will admit all this in a moment, Ctesippus, if you answer my questions, said Dionysodorus. Tell me, have you got a dog?
— Yes, and a brute of a one too, said Ctesippus.
— And has he got puppies?
— Yes indeed, and they are just like him.
— And so, the dog is their father?
— Yes, I saw him mounting the bitch myself, he said.
— Well then: isn’t the dog yours?
— Certainly, he said.
— Then since he is a father and is yours, the dog turns out to be your father, and you are the brother of the puppies, aren’t you?
Plato, Euthydemus, 298d-e. CW, p. 737
This argument is not intended to convince Ctesippus that he is son and brother of a dog. The sophist does not deceive his listeners, he leaves them confused and infuriated.
The sophists have devised thought-provoking paradoxes such as the following one:
Antiphon the Sophist claimed that the law, by obliging man to testify the truth before the courts, often compels us to do wrong to one who has done us no harm, that is, to contradict the first precept of justice.
Émile Bréhier, [History of Philosophy], 1928.
The Sophists represent, with the Skeptics, an essential intellectual movement within argumentation theory. The Sophists established the principle of debate and irreducibly contradictory discourses, as the foundational cases presented in Antiphon’s second Tetralogy, about a prosecution for accidental homicide; the case is discussed as follows:
First Speech for the Prosecution
Reply to the Same Charge
Second Speech for the Prosecution
Second Speech for the Defense
The intellectual and social contributions of the historical sophists have been stigmatized by Platonic idealism that imposed on them deformations which were suffered until Hegel in philosophy and are surviving in common language. Ancient Sophists were no more sophists in the contemporary sense of the word than Duns Scott was a dunce.
2. Contemporary usage:
the sophism, an intentional paralogism
In contemporary language, a sophism is an eristic, that is, a misleading discourse. From an interactional point of view, it is an embarrassing, false, manipulative and dangerous discourse, received as evidently false but the refutation of which is difficult. As any kind of discourse can be denounced by calling it a “sophism”, the concept is essential for the analysis of the polemical reception of argumentative discourse.
A sophism is a paralogism enveloped in malicious speech, produced to pull the rug from under the opponent’s feet. The distinction between sophism and paralogism is based on a charge of shameful intent, which may or may not be properly laid out. Paralogism is on the side of error and stupidity; sophism is a paralogism serving the interests or passions of its author. Under the principle of “who benefits from the crime?”, such an “error” is charged with malicious intent by the recipient and the potential victim. One moves from description to the accusation embedded in the negative contemporary use of sophist, sophistry, S. Fallacies: Aristotle foundational list, Paralogism.
 Émile Bréhier, Histoire de la Philosophie, Vol. 1, Antiquité et Moyen Âge [Antiquity and Middle Ages] Paris: PUF, 1981, p. 74.
 Antiphon, Second Tetralogy. KJ. Maidment, ed. Quoted after www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.01.0020%3Aspeech%3D3