The Greek of this sentence is certainly not clear. First, the verb which the Good News Translation has translated concluded … was responsible may mean either “to conclude” or “to instruct, advise.” Second, one would normally expect that the verb would have a double object when used with a person, that is, the person and the content of what was included or instructed. However, in the present sentence the second object is lacking, and Alexander is the only object of the verb. If one translates the text as it stands, one must conclude that the crowd either explained something to Alexander (see New English Bible) or that the crowd concluded something about Alexander (so Good News Translation). Phillips and Jerusalem Bible base their translation on an alternative manuscript reading. This verb appears in two other places in Acts (9.22; 16.10). In 16.10 it definitely means “conclude” or “decide”; while its use in 9.22 (rendered his proofs … were so convincing) may be taken to support either position, that is, that Paul was teaching or that he was concluding (proving) that Jesus was the Messiah. Luke gives no reason why Alexander wanted to make a speech of defense; there are no grounds for assuming that he wanted to defend Paul, and his entire relationship to the uproar is obscure.
It is difficult to translate was responsible without knowing precisely the relationship of Alexander to the issues in question; and since the Greek text does not make this clear, one can only attempt to use some meaningful equivalent which will be as general in implication as possible. However, in some languages one cannot avoid specifying the particular nature of the responsibility. In some instances the closest equivalent is “was important with respect to what had happened” or “was involved in what had happened.” It may even be possible to translate this expression as “had something to say”—perhaps the most general way of talking about Alexander’s role.
Motioned with his hand may be translated in such a way as to indicate that this particular gesture was designed to quiet the crowd or to induce them to listen to him. On the other hand, it may be necessary to supplement this mention of the gesture by “motioned with his hand so that people would keep quiet.”
Since we do not know Alexander’s role, it is difficult in some languages to translate the term defense. However, since Jews were known as opponents of idolatry, and since any riot in favor of Artemis might be interpreted by some people as an indirect attack upon the Jews, it may be that Alexander was put forward by Jews in order to explain to the crowd that the Jews themselves were not responsible for what had happened. If this was the situation, one may translate make a speech of defense as “speak to the people to show that he and his companions were not guilty of what had happened.” In a number of languages it is necessary to speak of a defense in terms of “saying that one is not guilty.”
Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on The Acts of the Apostles. (UBS Handbook Series). New York: UBS, 1972. For this and other handbooks for translators see here .