Using a general concept to prove a specific claim

This has been on my mind for a while. Sometimes people give opinions that they fail to support with specific evidence, but instead, claim that because some general principle or trend may apply to the situation, that their specific claim is correct or likely to be correct.

Example:

Amy: Violent video games cause gamers, specifically males, to become more violent.

Brent:  Where's your evidence for this?

Amy:  Well , it's a well-known fact that media can affect the way we perceive the world and the people in it. Video games are a form of media, therefore they affect the way we perceive the world and its people - so they do cause more violence.

I'm thinking possible ad-hoc rescue (since Amy has no real reason to believe what she does), or appeal to probability (in disguise; she states that media can affect the way people think, and therefore since VGs are media, affect people in the specific way that she claims).

I plan to post more questions in the future, so I'll thank you in advance for making me feel welcome. I'll also thank Dr Bennett for designing this wonderful website; I've been a lurker for some time now.

Hello Rationalissimo and welcome.

First, establishing causality is quite difficult and done through controlled experiments. Amy clearly has not done any experiments nor is she referencing any, so right out of the gate we can stop her there.

Here is Amy's argument:

P1: Media can affect the way we perceive the world and the people in it.

P2: Video games are a form of media.

C. Therefore, video games affect the way we perceive the world and its people - so they do cause more violence.

The second problem is that we moved from a possibility in P1 to a certainty in the conclusion. "Media can affect" to "video games (do) affect." We can't do this. At best, we can say video games can affect, preserving the possibility. This is the Appeal to Possibility .

Third, we have an ambiguity problem. In P1 we refer to "media" and in P2 we move to a form of media. This is like saying cats make great pets, lions are a form of cats, therefore lions make great pets. Without specificity, we can hide absurdity in ambiguity. This is the Ambiguity Fallacy .

Finally, we have a classic Non Sequitur . "So they do cause more violence" is just thrown on the end of the argument (ad hoc as you say), without support. If it were logically demonstrated that video games affect how we see the world, we have a long way to go to conclude that it makes gamers more violent.