This video is an overview and supplement to chapter 2 of David Morrow's book
Giving Reasons. Previously we had covered that knowledge is justified true belief.
In this chapter Morrow talks about how we justify our
beliefs, and he goes through five different methods that we use, five
different types of justification that we can offer for beliefs that we hold.
The first is justification by definition. This is where we justify a belief by
appealing to the meaning of the words involved. And as Morrow notes, this is
useful in mathematics and in some other abstract sciences, but it's not terribly
useful for establishing some really important claims in other more practical
fields. The second way is justification by perception. This amounts to appealing
to the evidence of my senses. I can see or feel or hear something for myself or
I can remember seeing or hearing or feeling it for myself. So if I believe
that it's raining I could say my justification for that is that I can see
and feel the rain right now, or that I can remember seeing and feeling the rain
a short time ago when I was last outside. The third type of justification is
justification by testimony. This amounts to trusting someone else's report of
what she saw or felt or heard. So if I believe that it's raining because my
sister came in from outside and told me that she had seen and felt the rain or
that she remembers seeing and feeling it some time ago, that would provide a
justification by testimony for my belief that it is raining, even though I don't
perceive the rain myself. This does have the additional requirement of evaluating
the truth or the honesty of the person whose testimony were choosing to trust.
The fourth type of justification is justification by authority, and this
amounts to appealing to experts. Now there is no one-size-fits-all expert
who is expert about everything, so we can't just go to one wise man and say
we'll take his word for everything on every subject. Instead we
have to decide who is going to be acceptable as an expert for a particular
claim or a particular field. And Morrow points out correctly that there are
really two tests that we need to apply before we rely upon justification by
authority. First, we need to satisfy ourselves that the expert involved is
well-informed, that he is knowledgeable, that he knows the truth about the
subject that we are accepting his word for. We might do this by looking at
someone's credentials or by the way in which other people have trusted them.
If a certain expert has given congressional testimony or has been trusted by
multiple diverse news outlets on a particular topic, this would stand in
favor of accepting them as an expert in this area, as someone who is
knowledgeable. The expert must also be impartial or unbiased, that is, he must
have a motivation to tell the truth to us about this topic at this particular
place and time. At the very least, he must not have any obvious motive to conceal
the truth or to mislead us. So I would want to evaluate my expert to
make sure he's not being paid by somebody to mislead me, that he's not
being blackmailed, that he's not in the grip of some ideological mania or
motivated by personal animus to mislead me in particular about the subject that
I'm trusting him on. If I do have an expert who is knowledgeable and
impartial, then I can use his testimony to establish the justification for a
belief on the basis of his authority. The fifth type of justification is
justification by reasoning. This means giving an argument or a series of
arguments to back up the belief or the claim that I'm evaluating. It means
giving reasons and showing that those reasons are good reasons for believing
the claim in question. This will often be a multi-step process; it will not be as
simple as simply pointing to an expert, establishing the expert's reliability and
expertise, and trusting him. It's going to mean getting down into the details of
the particular claims that I'm making and that I'm evaluating. This is, however, the
most important type of justification for philosophy, and for this course. We're
going to be looking at arguments that philosophers have given on a number of
topics going forward. That's all for today. Thanks for watching; goodbye.