why flaw?

mc_meatt

"The editorial board of this law journal has written on many legal issues. Tom is on the editorial board, so he has written on many legal issues."

It sounds like a valid reasoning... Why is it flawed?

Thanks in advance!

Pacifico

If there are more people than just Tom on the editorial board then he doesn't have to write anything for the board itself to write on many legal issues. Picture an actual law journal at a school that has 10 students on the editorial board. One or two or nine of those students could write on many legal issues satisfying your first sentence, and Tom could be a total slacker and not write anything, or he writes a lot but only about one legal issue. This is a classic part versus whole flaw where what is true of the whole does not have to be true of each individual part. What is true of the editorial board as a whole does not have to be true of each member.

mc_meatt

@Pacifico Thanks! How about this one? "The students at this school take math. Mike is a student at this school, so he takkes math."

Could you explain how that is different from this? Thank you!

DumbHollywoodActor

It’s a whole-to-part flaw, While the editorial board has written on many issues and Tom is on the editorial board, it’s entirely possible he’s only written on one issue. Maybe his role on the board is purely ceremonial and he does no writing whatsoever.

Hope it helps.

runiggyrun

The second one means "ALL students at the school take math". Each and every one. Including Mike. For part-vs-whole arguments it is crucial to distinguish whether a characteristic presented describes the whole or whether it describes each of the parts.
Here's another example:
Premed students take organic chemistry. Premed students major in a variety of disciplines. Mary is a premed student. You can see that this means she takes organic chemistry (characteristic describing all of the students) but probably only majors in one discipline (the variety of majors is a characteristic of the whole, not of each part)

MrSamIam

@DumbHollywoodActor Beat me to it.
As a whole, the BOARD has written on many legal issues. So, if there are 5 members on the board, we know that all together, those 5 members have written on many legal issues. Tom could be that lazy jerk who doesn't contribute much.
For instance, if 500 = "many" and the board as written on 500 legal issues, than they wrote on many legal issues. But what if the breakdown went a little something like this:
Jeff: Wrote on 100
Tom: Wrote on 100
Sarah: Wrote on 100
Lezlie: Wrote on 199 (she's a trooper...don't ask)
And then we have lazy Jeff: Wrote on 1.

Did the group, as a whole, write on many legal issues? Yup, 500 to be exact. How about Jeff? Absolutely not, he was watching Netflix the entire time, and managed to only push out 1 article.