Please define, because I'm confused.

A man who uses reason?

Same as a reasonable woman but with BOLLOCKS!

Most men just talk Bollocks ..........

I think the term "a reasonable man", when used in a dating sense, is someone who is amenable to persuasion and not a shouting, angry type.

Not necessarily amenable to persuasion, just reasonable in certain circumstances.

For example, on a Saturday afternoon if she has some DIY she'd like you to do but you really, really want to watch the footie, being reasonable would be to say "I've been looking forward to this match all week babes, but i promise you as soon as the match is over i shall do it". And then actually sticking to that promise!!!! lol That's being reasonable

depends who it is that is referring to a "reasonable man".

If its a bloke talking about a reasonable man then he means someone who would buy him a pint!

If its a woman describing a reasonable man she means a man who doesn't ever disagree with her!

A man who can be manufactured into chocolate chews?

Being reasonable is probably wasted on some women.

The only times I have ever heard anybody refer to someone else as "unreasonable" was when they simply couldnt persuade that person to see things from their own narrow point of view and got shitty about it.
I guess though in the grand scheme of things "reasonable" probably means, as Bex suggests, someone who is willing to compromise on occasion.

And Jegs, dare I suggest that sometimes 'being reasonable' is wasted on some men too?

Apparently its a man on the top deck of the Clapham omnibus, in legal terms at least

A man who does exactly as he's told to?

tim