Is it wise to go into a negotiation without evidence to support your argument? Why or why not?

Thanks for invitation.

Evidence is not only the documents but one should Gain knowledge by collecting and collating the following information about the subject will be negotiating:

• Statistics and solid figures.
• Facts that are supported by overwhelming evidence.
• Precedents that support your stance and point-of-view.
• An understanding of your opponent’s personality traits.

Negotiation is a dance and obviously practice make perfect. It will be folly to get to a dancing contest without practicing and perfecting your moves. Likewise, one should be prepared and have all the facts ready for the best outcome. A negotiator should assemble  a capable team with requisite skills to tackle items on the Agenda. Arguments will ensue but the team with the best evidence or facts will win all marbles.

with out knowing the evidence, jumping in to any negotiation is just like jumping into a river with your hand and legs tied. so one must not even think about doing so. with out facts and evidence one can only embarrass himself because he will be unable to answer any question properly and well fail to defend his motive as well...

It is always preferred to first have valid research and data facts before going into the negotiation stage.

Person should display knowledge about his/her product/service, that will help in building assertiveness & conviction.

It really depends on what the issue is. I always find that in relation to a technical matter it is best to be informed, in other words having all your facts and figures lined up, completing a sensitivity analysis, (BATNA- WATNA); what you do with them (facts or figures) and how you use them is a function of desired outcome. You play them as you need them without giving anything away that can be used to out maneuvor you. For non technical matters the issues are less objective but more subjective. In this case your timing and strategy of resolution is more important than whether you are right or wrong. Being wrong can be deliberate and used as a distraction while the real issues are being attacked.  

Any type negotiations buyer should have  the data and evidence and past history of  trends. I strongly believe  that  there is no end for  negotiations. Still we have to find out the point of conclusion by the experience  which we have and should be agreed  by both the parties.

evidences to support your arrguments are highly desirable but negotiation is more than a display of evidences, it's influencing other, persuading them to follow your path. It's both cognitive and emotional process.

Argument is a step of the Negotiation Process< Where Preparation is the most important step

so it's not wise at all to negotiate without Preparation, without knowing your target, your parties, and your preservation price

Negotiation is a co-operate with two parties to achieves each one the target . 

you cannot negotiate without evidence to prove your argument 

thats a direct win to your opponent cause you are not prepared with facts to put down 

Without evidence you can nit support your argument because you are talking useless and you will not convince even a single person. in a research if you are saying something so, you will need justification for it. in a same manner if you are saying something so you will have to provide evidence for it. when you are talking with evidence people will trust you. but without evidence you are going on a road with no destination.