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experiences of similar occasions
on which we have found things
like balls to fall to the ground
when we release them.
Deductive reasoning
Another form of reasoning,
which philosophers contrast with
induction, is deductive reasoning.
While induction moves from the
particular case to the general,
deduction moves from the general
case to the particular. For instance,
a piece of deductive reasoning might
start from two premises, such as:
“If it is an apple, then it is a fruit
(since all apples are fruit)” and
“This is an apple.” Given the nature
of these premises, the statement
“This is an apple” leads inescapably
to the conclusion “It is a fruit.”
Philosophers like to simplify
deductive arguments by writing
them out in notation. So the general
form of the argument above would
be “If P then Q; since P, therefore
Q.” In our example, “P” stands for
“It is an apple”, and “Q” stands for
KARL POPPER
untrue, even though the argument
itself is valid, the conclusion is
also untrue. Other worlds can be
imagined in which cats are in fact
banana-flavored, and for this reason
the statement that cats
are not banana-flavored is said to
be contingently true, rather than
logically or necessarily true, which
would demand that it be true in
all possible worlds. Nevertheless,
arguments that are valid and have
true premises are called “sound”Every solution to a
problem creates new
unsolved problems.
Karl Popper“It is a fruit.” Given the starting
points “If P then Q” and “P”, then
the conclusion “Q” is necessary, or
unavoidably true. Another example
would be: “If it is raining, the cat
will meow (since all cats meow
in the rain). It is raining, therefore
the cat will meow.”
All arguments of this kind are
considered by philosophers to be
valid arguments, because their
conclusions follow inevitably from
their premises. However, the fact
that an argument is valid does not
mean that its conclusions are true.
For example, the argument “If it is
a cat, then it is banana-flavored;
this is a cat, therefore it is banana-
flavored” is valid, because it follows
a valid form. But most people would
agree that the conclusion is false.
And a closer look shows that there
is a problem, from an empirical
perspective, with the premise “If it
is a cat, then it is banana-flavored”,
because cats, in our world at least,
are not banana-flavored. In other
words, because the premise isAn example of the
problem of induction is
that no matter how reliably
a tennis ball behaves in
the present, we can never
know for certain how it
will behave in the future.
Experiment A Experiment B Experiment C66°48° 48°66°??