The bullshit detection kit - Michael Shermer

Logical Fallacies 101: Argumentum ad populum

Argumentum ad populum is Latin for 'appeal to the people'. Arguments who commit this logical fallacy are arguments which support a particular proposition on the grounds that the majority, or a large group, of people believe that proposition.

The form of this fallacious type of argument says that A is true simply because the majority of people believe that A is true, supposing that the majority cannot be wrong.

Examples:
- Thousands of martyrs died defending Christianity, therefore Christianity must be the right religion. So many people could not have been wrong.
- 60% of Americans do not believe in the theory of evolution, therefore it cannot be right.
- Everyone else in this meeting adopted my position, so you should do so as well.
- There was no opposition to this new law so I guess it must be fair and exactly what people wanted.

The reason this is considered a fallacy lies on the case that the amount of people believing a proposition does not indicate whether that proposition is true or false. People's belief system does not have any effect on the proposition itself and, in fact, the proposition would be true even if there were no minds to perceive it.

The case that 75% of Americans believe that the earth orbits the sun [1] cannot be an indicator that that particular proposition is true, but it must be weighed upon scientific theories and mathematical calculations, based upon existing models of the solar system, to assess the proposition.

When it comes to more advanced theories or findings, however, things become a bit more complicated. On the above grounds, one might argue that the fact that 97% of scientists believe in human-caused global warming means that human-caused global warming is true. [2] (Linked with the next fallacy: Appeal to authority). That's a mistaken way to approach the issue. The fact that 97% of scientists believe in human-caused global warming only raises the possibility that that proposition is true. It in no way guarantees it. What guarantees the truth of the proposition is the experiments that have been done, and the theories that were proposed to test the proposition, published in peer-reviewed journals. This is the reason, therefore, why appealing to the majority is always a fallacious argument and must be in any case avoided.

[1] http://time.com/7809/1-in-4-americans-thinks-sun-orbits-earth/
[2] http://skepticalscience.com/97-percent-consensus-cook-et-al-2013.html

Logical Fallacies 101: Ad hominem

Being an atheist, secularist, and humanist society, DASH is committed in using reason when developing arguments. Reason differs from belief in the sense that it is a secure way to truth - or how philosophers would call it: 'the way things are'. And, as the Great Tyson (Neil, not Mike - though he is also great) said: "'The good thing about science is that it's true whether or not you believe in it."

However, we all sometimes fall into the trap of committing logical fallacies when arguing, fallacies which may convince but they are not based on firm sound grounds. DASH will weekly present one logical fallacy in an attempt to promote arguing with reason and developing sound arguments.

Ad hominem fallacy



Ad hominem is Latin for "to the person". It is a personal verbal attack to the person making an argument, rather than to the argument itself. Person B presents a fact about person A that is supposedly related to the argument A is trying to make, and rejects A's argument on that particular fact. 

The structure of the fallacy is this:

1. Person A makes claim X
2. Person B disregards the claim and attacks person A.
3. Thus, claim X is false.

The reason this is a fallacy is that any fact about A is unrelated to claim X. Claim X is or is not true, irrespective of who is the person arguing for it.

A different form of this fallacy is the circumstancial ad hominem. This is an attack on the person making a claim, on the grounds of that it is in his own interests to make a claim.

Example:

1. Person A: Decreasing the interest rate would be a good thing for the economy.
2. Person B: Ofcourse you would say that. You are a banker! And definitely bankers are expected to promote such views.

A's argument's truth is irrelevant to any fact about A; in this case his job. Even if A supports that claim because he is a banker, B should attack the argument using economic, financial, or other relevant, terms. The key is that in such terms, B is able to objectively criticize A's claim.

"Are ad hominem arguments always fallacious?" you may ask. Yes, in most cases. However, there is an exception. The above cases are cases in which person A was making an argument. A's credibility was irrelevant. In cases of a statement of fact, however, that is when A is making a testimony, A's credibility is of utmost importance and needs to be assessed.