Agreement, Partial Agreement And Disagreement.

The ways in which people agree or disagree in a discussion varies in different languages.

Agreeing

It is worth understanding that silence is not to be understood as an agreement. If you agree with someone's opinion or idea, you are required to say so.

Expressions

There is no doubt that...
I completely / absolutely agree with you.
I agree with you entirely.
I totally agree with you. 
I simply must agree with that. 
I am of the same opinion. 
That’s exactly what I also think.

Disagreement:

Expressing disagreement is always considered honest, and sometimes courageous

Expressions

I don't agree with you.
I’m sorry, but I disagree. 
I'm afraid, I can't agree with you. 
The problem is that... 
I doubt whether... 
This is in complete contradiction to... 
With all due respect,…
I have a different opinion about this because ... 
I cannot share this / that / the view. 
I cannot agree with this idea. 
What I object to is... 
I have my own thoughts about that.

Partial agreement:

You can also agree but with reservation especially when there is a doubt or feeling of not being able to accept something completely

Expressions

It is only partly true that... 
That’s true, but…
I can agree with that only about...
That seems obvious, but... 
That is not necessarily so. 
It is not as simple as it seems. 
I agree with you in principle, but… 
I agree with you in part, but… 
Well, you could be right.