PLEASE READ•All observed brown dogs are small dogs. Therefore, all small dogs are brown.

All observed basketball players are tall, so all basketball players must be tall.

PLEASE READAll Christians believe in Jesus Christ. Daniel is a Christian. Therefore, He believes in Jesus Christ.

All students in Socio-Philo are intelligent and smart. I am one of the students in Socio-Philo. Therefore, I am intelligent and smart.

heheheheh

PLEASE READAll carabaos are hardworking. Filipinos are hardworking. Therefore, Filipinos are carabao.

A guy sees his new neighbor out in his backyard, so he decides to get acquainted. After introductions, he asks the new neighbor what he does for a living.The new neighbor says, "I'm a professor." The first neigbhbor then asks, "Oh yeah, what do you teach?""Logic," the professor reponds."What is that?" the neighbor inquires."Well, let me see if I can give you an example...you have a dog, right?""Yeah, that's right," neighbor #1 responds."And you have children too, right?" says the professor."Wow, right again!" exclaims the neighbor."So, then you must be married and that would make you a heterosexual, right?'' proclaims the professor."Unbelievable, you're absolutely correct. How do you know all this about me?""Well," the professor says, "I observed there was a dog house in your backyard, so you must have a dog. I also saw bicycles next to your garage, so you must have children. And if you have children, you are probably married and if your married, you are most likely heterosexual... it was all logical!"The next afternoon, the neighbor runs into his old friend. His friend asks if he has met the new neighbor. The man says that he met him yesterday."What's he like?""Well," the man says, "he's nice and he is a professor of logic.""Oh," says the friend, "what's logic?""Maybe I can give you an example. Do you have a dog house?""Why, no, I do not," responds the friend."Well, then," proclaims the man, "you must be gay!"

A couple wants a divorce, but first they must decide who will be the main guardian of their child. The jury asks both the man and woman for a reason why they should be the one to keep the child. So the jury asks the woman first. She says, "Well I carried this child around in my stomach for nine months and I had to go through a painful birth process, this is my child and apart of me." The jury is impressed and then turns to ask the man the same question. The man replies, "OK, I take a coin and put it in the drink machine and a drink comes out, now tell me who does the drink belong to me or the machine"

LOGIC: ITS NATURE AND CHARACTERISTICS

By Marver O. Bolonia

LOGIC Logic (from the Greek  logike) has two meanings: first, it describes the use of valid reasoning in some activity; second, it names the normative study of reasoning or a branch thereof. In the latter sense, it features most prominently in the subjects of philosophy, mathematics, and computer science.

a proper or reasonable way of thinking about or understanding something

the science that studies the formal processes used in thinking and reasoning

a science that deals with the principles and criteria of validity of inference and demonstration : the science of the formal

principles of reasoning

a particular mode of reasoning viewed as valid or faulty

interrelation or sequence of facts or events when seen as inevitable or predictable

Logic is the study of the methods and principles used in distinguishing correct from incorrect reasoning.

Reasoning is an art as well as a science: it is something we do as well as understand. The mental recognition of cause-and-effect relationship is called ‘reasoning’.

Logical Reasoning

It may be prediction of an event from an observed cause or the inference of a cause from an observed event.It is a process of passing from the known to the unknown. It is the process of deriving a logical inference from a hypothesis through reasoning.

LOGIC IS OFTEN DIVIDED INTO 2 BROAD METHOD OF REASONING

INDUCTIVE REASONING

DEDUCTIVE REASONING

DEDUCTIVE REASONING Deductive reasoning happens

when a researcher works from the more general information to the more specific.

Sometimes this is called the “top-down” approach because the researcher starts at the top with a very broad spectrum of information and they work their way down to a specific conclusion.

"All men are mortal. Marver is a man. Therefore, Marver is mortal.“

Every day, I leave for work in my car at eight o’clock. Every day, the drive to work takes 45 minutes I arrive to work on time. Therefore, if I leave for work at eight o’clock today, I will be on time.

An example of deductive reasoning can be seen in this set of statements:

For example, the argument, "All bald men are grandfathers. Harold is bald. Therefore, Harold is a grandfather," is valid logically but it is untrue because the original statement is false

It's possible to come to a logical conclusion even if the generalization is not true. If the generalization is wrong, the conclusion may be logical, but it may also be untrue

Syllogism

A common form of deductive reasoning is the syllogism, in which two statements — a major premise and a minor premise — reach a logical conclusion. For example, the premise "Every A is B" could be followed by another premise, "This C is A." Those statements would lead to the conclusion "This C is B." Syllogisms are considered a good way to test deductive reasoning to make sure the argument is valid.

INDUCTIVE REASONING Inductive reasoning is the opposite of

deductive reasoning. Inductive reasoning makes broad generalizations from specific observations.

This is sometimes called a “bottom up” approach. The researcher begins with specific observations and measures, begins to then detect patterns and regularities, formulate some tentative hypotheses to explore, and finally ends up developing some general conclusions or theories.

Robert is a teacher. All teachers are nice. Therefore, it can be assumed that Robert is nice.•Suzy is a doctor. Doctors are smart. Suzy is assumed to be smart.

•All observed police officers are under 50 years old. John is a police officer. John is under 50 years old.

EXAMPLE OF INDUCTIVE REASONING

While inductive reasoning is commonly used in science, it is not always logically valid because it is not always accurate to assume that a general principle is correct.

Even if all of the premises are true in a statement, inductive reasoning allows for the conclusion to be false. Here’s an example: "Harold is a grandfather. Harold is bald. Therefore, all grandfathers are bald." The conclusion does not follow logically from the statements.

By nature, inductive reasoning is more open-ended and exploratory, especially during the early stages. Deductive reasoning is more narrow and is generally used to test or confirm hypotheses.

Most social research, however, involves both inductive and deductive reasoning throughout the research process. The scientific norm of logical reasoning provides a two-way bridge between theory and research. In practice, this typically involves alternating between deduction and induction.

ACTUAL PRACTICE AND ITS USE

Inductive reasoning has its place in the scientific method. Scientists use it to form hypotheses and theories. Deductive reasoning allows them to apply the theories to specific situations.

ACTUAL PRACTICE AND ITS USE

THANK YOU FOR LISTENING

PROPERTIES OF LOGICAL SYSTEMS Consistency, which means that no

theorem of the system contradicts another.

Validity, which means that the system's rules of proof never allow a false inference from true premises.

Completeness, of a logical system, which means that if a formula is true, it can be proven (if it is true, it is a theorem of the system).

Soundness, Soundness refers to logical systems, which means that if some formula can be proven in a system, then it is true in the relevant model/structure . This is the converse of completeness. A distinct, peripheral use of soundness refers to arguments, which means that the premises of a valid argument are true in the actual world.