The speaker of that evening stated that:

1) insects and fish do not suffer nor feel pain, because they have no consciousness
2) for that reason they do not have any rights as human beings have, who do have consciousness.

The “proof” he offered for the claim, that these animals do not suffer when cut in pieces (1), was weak, but even if it was not so, even if it was a strong consistent proof, one cannot conclude (2) from (1). Why would anybody want to connect consciousness to rights?

Should I, as the moderator, have intervened and pointed out the fallacy or should I have trusted the group, so that maybe someone in the group would have shown, that these issues are not related?

I trusted the group. Luckily, that evening some participants pointed out the fallacy. It also could have happened that participants had changed the focus to some other aspect of the issue and that the fallacy would have remained unanswered. Does a philosophical café, where the philosopher who moderates it, lets participants say whatever they want, make sense? Is that what participants expect the philosopher to do?

Do people learn if they are being corrected? And if not, does this mean that we should not bother to say anything when they say something wrong? Is it our purpose to educate others, in the first place? Do we want to make them think? Why so?”

There are no general answers to these open questions. Nevertheless there might be some appropriate answers to each one of them in a specific context, a specific matrix, containing specific kinds of participants (levels of understanding, capacity of interacting, willingness to let the dynamic flow) and at a specific moment in the session (what has been said before, the way the interaction has been going on so far, the direction towards which the conversation or discussion is flowing).

As philosophical practitioners we actually can offer appropriate answers, nevertheless only submerged by practice into a specific context.