それは討論に適切な論題ではない。の英語

It's not a suitable topic for discussion.

This argument is not deductively valid.

It is an impracticable argument.

This argument is not a valid

The argument has no force.

The argument will not hold.

That problem is still being debated.

That is an incontestable truth.

There is no point arguing about the matter.

That is not a valid argument.

It's no use arguing about it.

It is no use arguing about it.

I think I have a topic which needs to be discussed.

Your argument is illogical.

Your argument does not hold water.

That is a matter for debate.

Your argument does not hold water.

I was out of my depth in that debate.

There is no end to this argument.

Such arguments make （not for, but） against your interests.

A discussion of the proposal seems to be in order.

It is useless even if I discuss with you.

The argument is contrary to reason―against reason.

We have to admit that there was an aporia in our debate.

This discussion topic is very difficult to debate in English.

a noisy argument lacking content

Let's put a stop to this discussion.

Let's not argue for the sake of arguing.

It is an argument founded on false data.

Your argument is illogical