Logic is the study of the principles of valid inference and demonstration. The word derives from Greek ?????? (logike), fem. of ??????? (logikos), "possessed of reason, intellectual, dialectical, argumentative", from ????? logos, "word, thought, idea,

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Logic is the study of the principles of valid
inference and demonstration. The word derives
from Greek ?????? (logike), fem. of ???????
(logikos), "possessed of reason, intellectual,
dialectical, argumentative", from ????? logos,
"word, thought, idea, argument, account, reason,
or principle".
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Philosophy is centered around arguments A The
study of arguments is called logic, which is the
process of supporting a thesis called the
conclusion with reasons called premisesB An
argument consists of at least two declarative
sentences called prepositions one of which (the
conclusion) logically follows from the others
(the premises)i.     This connection in which
the conclusion follows from the premises is
called an inference
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Deductive arguments
A.     Valid one that follows a correct logical
form - if the premises are true, the conclusion
is also true 1 Preserves truth-if statements are
true, the form is correct, then conclusion will
always be true 2        Example. the subject is
Socrates, the predicate is mortal, and the middle
term which connects the two previous terms is
man. When using all three terms, if you were to
state that Socrates is a man, and that all men
are mortal you would be lead to a true conclusion
that states that Socrates is a mortal. B
Invalid having an improper form and cannot yield
a valid conclusion
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        Inductive Arguments
.        a.     Not truth preserving- no
guarantee that if the premises are true that the
conclusion will be true b.     Only bring
probability c.     Premises are considered
evidence for the conclusion   i.      If evidence
is substantial, then the argument is a strong
inductive argument   ii.      If evidence is
weak, so is the argument as a wholed.     Can be
misleading i.      Prejudice- generalizing from
an inadequate sample e.     Reasoning by analogy-
reasoning from the similarity of two things in
some relevant respects to their similarity in an
unexpected respect. i.      Example being lost
in a forest, wanting to determine if I should eat
a certain mushroom because Im hungry. I note
that it is similar in shape, color, and
constituency with other mushrooms that turned out
to be edible. Thus I infer that this mushroom
will probably be edible too.
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Difference Deduction/Induction
Deductive reasoning refers to the process of
concluding that something must be true because it
is a special case of a general principle that is
known to be true. For example, if you know the
general principle that the sum of the angles in
any triangle is always 180 degrees, and you have
a particular triangle in mind, you can then
conclude that the sum of the angles in your
triangle is 180 degrees. Inductive reasoning is
the process of reasoning that a general principle
is true because the special cases you've seen are
true. For example, if all the people you've ever
met from a particular town have been very
strange, you might then say "all the residents of
this town are strange". That is inductive
reasoning constructing a general principle from
special cases. It goes in the opposite direction
from deductive reasoning
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Sound/Unsound Arguments
Soundness if an argument that has a valid form
and all of its premises are true Unsound if an
argument has at least one false premise Example
1. if Mary is a mother, she must be a woman 2.
Mary is a mother (for she has given birth to a
baby) 3. Mary is a mother- if Mary hasnt given
birth, then premise 2 is false and the argument
is unsound.
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Reductio ad Absurdum Reduce to an Absurdity or
Contradiction
Zeno's paradoxes were a major problem for
ancient and medieval philosophers, who found most
proposed solutions somewhat unsatisfactory. More
modern solutions using calculus have generally
satisfied mathematicians and engineers. Many
philosophers still hesitate to say that all
paradoxes are completely solved, while pointing
out also that attempts to deal with the paradoxes
have resulted in many intellectual discoveries.
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