Whether you're negotiating the price of a massive contract, or a salary raise that comes with a new position, negotiating skills are essential in the business world. If you're unable to negotiate fairly, logically, and persuasively, you could jeopardize your career, or at least miss out on significant opportunities as a result.

When trying to argue persuasively, participants sometimes rely on logical fallacies, or illogical arguments that seem rational at first glance, to prove their points. It's critical to avoid the emergence of such fallacies, as they can immediately weaken your argument. Likewise, it's important to observe the other party's arguments carefully, and point out any fallacies that may form the crux of his/her argument.

The key to most successful negotiations is planning, and you can avoid the pitfalls of logical fallacies by brainstorming about what possible fallacies could come up during negotiations. Preparation allows you to chart a course for your position, plan for possible rebuttals, consider possible alternatives and compromises, and determine the consequences of the negotiation's outcome. Seeing ahead this far should give you the opportunity to analyze your own argument for any potential weaknesses, and look for potential weak points in the other party's argumentative course.

As you prepare for the negotiation, keep the following dangerous logical fallacies in the back of your mind.

1. Straw man argument.

A straw man argument is an instance of one party misquoting or deliberately inventing a false version of another party's argument in an effort to make their own argument seem more appealing. For example, let's say your potential client claims that they can't engage in your services because they don't have enough available funds. You distort that argument by saying, "You say you don't think our services are worth the money, but I can prove objectively that we'll increase your ROI."

This is a straw man argument, because the argument you're trying to counter is not the same argument they initially presented. While the two arguments (real and distorted) are somewhat similar, you aren't actually addressing the point at hand. This could weaken your position or make the other party frustrated.

2. Appeal to consequences.

This type of fallacy is usually a sophisticated form of appealing to emotion, but sometimes it just cuts an important argumentative corner. Appealing to consequences is a way of asserting that an idea is true by arguing that the consequences of the idea's not being true are undesirable. A traditional example of this is arguing that free will has to exist because if it didn't life would have no point.

You may find yourself stumbling into this type of logical fallacy in a business negotiation. For example, if you're trying to negotiate an increased rate to your customer, you could say, "We are responsible for keeping your sales up. If we weren't, we wouldn't be in business." You can make the claim that you are responsible for their increased sales, but you need to back that argument up with objective data--not a hypothetical argument of what would happen if you weren't.

3. Ad hominem.

Ad hominem is a type of fallacy that involves attacking another person's character rather than his/her argument. You see this type of fallacy often in the political circuit; rather than diving into the logistics of the issue at hand, one candidate will accuse the other of being a liar.

While you wouldn't dare make such an obvious attack in the business world, this logical fallacy does have a tendency to pop up from time to time during negotiations. Let's say you're a candidate for a promotion, and the opposing candidate has argued that he is better educated than you. It's a logical fallacy if you try and refute this argument by saying something like "he probably didn't study as hard as I did." Instead, opt to argue that your experience means more than education, or find some other way to overcome the argument without undercutting the opposing party's character.

4. Slippery slope.

You see the slippery slope fallacy all the time during political debates. One person argues against the proposition of a new law or regulation simply because there's a chance that it could lead to more significant laws or regulations in the future.

Put this into a business perspective. Let's say you want your employee to take on a new responsibility, and he/she is resistant. It's a logical fallacy if he/she resists because he/she is afraid that by saying yes to this new responsibility, it will open the door to many new unwanted responsibilities. It's not logical because the argument is for only one additional responsibility, and the future is entirely hypothetical.

5. Correlation equals causation.

This argument is an especially tempting trap to fall into. Correlation is an observation that one action was taken and one result was obtained. It doesn't necessarily prove that the action was what caused the result; arguing that it did is a logical fallacy.

For example, if you're negotiating for a pay raise, it's illogical to argue that an increase in productivity was due solely to your own efforts. Let's say you're in marketing and your company's social media following increased since the time of your last evaluation. You can't tie your performance to those increased metrics unless you have a causal link. Otherwise, they could easily be attributed to a new company announcement, or an outlier in your data.

6. False dilemma.

The false dilemma fallacy starts with an assumption that there are only two possible answers to a solution, and those possibilities are at extreme ends of the spectrum. For example, if a co-worker is arguing against one of your plans for a given project and you argue, "You're either on board with this, or you're trying to sabotage the project," you've immediately created a false dilemma. The world is seldom black and white, and in this particular example, it's entirely possible that the co-worker is interested in the idea but is only trying to raise some possible concerns. Don't assume there are only two options for any scenario.

7. Red herring.

In detective stories, a red herring is a clue intended to lead the audience to one conclusion while the correct conclusion is different. In the context of negotiation, a red herring is a way of manipulating an argument instead of trying to address it. For example, if you and your boss are negotiating a pay raise and the subject of company budget comes up, it's a red herring if you keep changing the argument to the strength of your performance. You may have more leverage with performance than with budgetary concerns, but if you aren't addressing the budgetary argument, you're approaching the argument illogically.

Logical fallacies are a kind of poison that can infect an otherwise valid, valuable argument and render it completely useless. If you can spot and identify any in the other party's persuasive argument, you'll have the upper hand in crushing their argument totally. Likewise, you'll have to pay attention and keep them from encroaching on your own persuasive words. Doing so will put you in a better position, and strengthen your arguments.