About this video
This logical reasoning lesson works through a 'which must be true' question about genetic research funding. The instructor diagrams the premises as sets, then tests each answer choice by trying to build a scenario where it is false while every premise still holds. The option that cannot be false is the one that must be true.
You'll be able to
- diagram set-based premises such as almost all, some, and either-or statements.
- test an answer choice by constructing a scenario where it is false.
- tell the difference between what is plausible and what must be true.
Key words
- Must be true
- An answer that is guaranteed by the premises, so no possible scenario makes it false.
- Premise
- A statement given in the prompt that you assume is true when evaluating the answer choices.
- Diagram
- A sketch of sets, such as circles inside circles, showing how the premises relate to each other.
- Counterexample scenario
- A possible situation consistent with the premises that makes a given answer false, used to eliminate it.
- Almost all
- A quantifier meaning nearly every member of a group, which still leaves room for a few exceptions.
Transcript
- [Instructor] Almost all advances in genetic research give rise to ethical dilemmas. Government is the exclusive source of funding for most genetic research. Those projects not funded by government are funded solely by corporations. One or the other of these sources of funding is necessary for any genetic research.
Alright. If all of the statements above are true, then which one of the following must be true? Now before I even look at these choices, let's diagram this out a little bit. So this first statement says almost all advances in genetic research give rise to ethical dilemmas.
So let me draw a little diagram. So let's say that this is, this right over here, these are all the advances in genetic research. All advances from genetic research. Now they're not saying all of the advances lead to ethical dilemmas, they're saying almost all of the advances.
So I would say almost all. So this is almost all of them. So these are the ones we could say lead to ethical dilemmas. Ethical dilemmas. Alright, now what do they go on to say? They say government is the exclusive source of funding for most genetic research. Those projects not funded by government are funded solely by corporations.
One or the other of these sources of funding is necessary for any genetic research. Okay, so this is interesting. So the next thing we want to think about is well, not all research leads to advances. So, let's do it like this. So this is all of the research, a subset of which leads to advances.
So that's all the research, all of the genetic research. And then this research is going to be funded either by government or by corporations. They make that very clear. One or the other of these sources of funding is necessary for any genetic research. So this is going to be government or corporations.
Alright, now that we've diagrammed this out a little bit-- And we're assuming that, we have to assume that all of this is true. This might not actually be true, but if we assume they're all true, which of theses statements must be true? Most advances in genetic research occur in projects funded by government rather than corporations.
Well, that might be the case, but it doesn't have to be true. It's possible that the corporate funding is actually responsible for most of the actual advances. Maybe they fund better in some way, or they're more effective in some way. So that one definitely does not have to be true, even if we assume all of these statements are true, you could have a world in which the corporations somehow fund the research that has all the advances in it while the government funding isn't as effective.
So I would rule that one out. Most genetic research funded by government results in advances that give rise to ethical dilemmas. They're saying that research is funded either by government or by the private sector or by corporations. So this is the research right over here.
They're saying that look, some of it is funded by government, and some of it is funded by corporations. Now they say most genetic research funded by government results in advances that give rise to ethical dilemmas. Well we don't know that most of the research funded results in advances.
It might be a small amount of either that result in actual advances. Once again we have to pick the thing that must be true. So if we can figure out a situation that well, it doesn't have to be true, then we can rule it out. At least some of the advances in genetic research occur in projects funded by corporations.
Well once again we're not picking something that might be true or that sounds reasonable, we're trying to pick something that must be true. And I can construct a situation where all of the advances are sitting squarely on the government's side of what they are funding.
On this diagram right over here, maybe this is the stuff that the government is funding, and all of the corporate research doesn't lead to any advances. Now it might not seem likely or reasonable, but that could actually be the case that all of the advances are happening on the government side.
So we don't have to say that at least some of the advances in genetic research occur in projects funded by corporations. It feels like a reasonable statement, but it doesn't have to be true. No ethical dilemmas resulting from advances in genetic research arise without government or corporate funding.
So these statements up here they're saying we have these ethical dilemmas from advances in genetic research. That's this green area here. These are ethical dilemmas from the advances. And they're saying no ethical dilemmas resulting from advances in genetic research arise without government or corporate funding.
So if we took away the government and the corporate funding, the statements up here tell us that corporate and government funding are the only sources of research. Well then this research won't happen, in which case these advances won't happen, in which case you will not have these ethical dilemmas from the advances.
So this statement must be true. Now let's look-- Let me delete some of this marking up I did. So this needs to be true. Now let's look at this last choice. As long as government continues to fund genetic research, that research will give rise to ethical dilemmas.
Well, once again it might feel like a reasonable statement, something that might be true, but it doesn't have to be true. For example, all of the advances might be occurring in the corporate research. So if this one right over here, that might be the government and this might be the corporate.
All of the advances are happening in the corporate research, and some of them are causing the external ethical dilemmas. Maybe all of the government research is very inefficient. And in that case, that research will not give rise to ethical dilemmas. So this does not have to be true.
We definitely wanna go with D.
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