Logic > Umar Iqbal 2
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PRESENTATION OF LOGIC PRESENTED to : MADAM FOZIA PRESEMTED BY : UMAR IQBAL
INFERENCE
Inference is the act or process of deriving a conclusion based solely on what one already knows. Inference is studied within several different fields. Human inference. Logic studies the laws of valid inference
The accuracy of inductive and deductive inferences
The conclusion inferred from multiple observations is made by the process of inductive reasoning. The conclusion may be correct or incorrect, and may be tested by additional observations. In contrast, the conclusion of a valid deductive inference is true if the premises are true. The conclusion is inferred using the process of deductive reasoning. A valid deductive inference is never false. This is because the validity of a deductive inference is formal. The inferred conclusion of a valid deductive inference is necessarily true if the premises it is based on are true.
Valid inferences
Inferences are either valid or invalid, but not both. Philosophical logic has attempted to define the rules of proper inference, i.e. the formal rules that, when correctly applied to true premises, lead to true conclusions. Aristotle has given one of the most famous statements of those rules in his Organon
REASONING
Reasoning is the process of looking for reasons on which to base one's beliefs or actions. In philosophy, the study of reasoning typically focuses on what makes reasoning good or bad, appropriate or inappropriate. Philosophers do this by either examining the form or structure of the reasoning within arguments, or by considering the broader methods used to reach particular goals of reasoning, such as beliefs or actions. Psychologists, in contrast, tend to study how people actually reason, and how those methods of reasoning help or hinder people.
Reasoning and forms of argument
One approach to the study of reasoning is to identify various forms of reasoning that may be used to support or justify conclusions. The main division between forms of reasoning that is made in philosophy is between deductive reasoning and inductive reasoning. Formal logic has been described as 'the science of deduction' (Jeffrey, 1991, 1). The study of inductive reasoning is generally called either 'informal logic' or 'critical thinking'.
Deductive reasoning
Deductive arguments are intended to have reasoning that is valid. Reasoning in an argument is valid if the argument's conclusion must be true when the premises (the reasons given to support that conclusion) are true. One classic example of deductive reasoning is that found in syllogisms like the following: All humans are mortal. Socrates is a human. Therefore, Socrates is mortal.
VALIDITY
Validity is a property of the reasoning in the argument, not a property of the premises in the argument or the argument as a whole. In fact, the truth or falsity of the premises and the conclusion is irrelevant to the validity of the reasoning in the argument. The following argument, with a false premise and a false conclusion, is also valid, (it has the form of reasoning known as modus ponens). If green is a colour, then grass poisons cows. Green is a colour. So, grass poisons cows.
Inductive reasoning
Inductive reasoning contrasts strongly with deductive reasoning. Even in the best, or strongest, cases of inductive reasoning, the truth of the premises does not guarantee the truth of the conlusion. Instead, the conclusion of an inductive argument follows with some degree of probability. Relatedly, the conclusion of an inductive argument contains more information than is already contained in the premises. Thus, this method of reasoning is ampliative. A classical example of inductive reasoning comes from the empiricist David Hume: The sun has risen in the east every morning up until now. So, the sun will also rise in the east tomorrow.
Abductive reasoning
However, as the conclusion in an abductive argument does not follow with certainty from its premises it is best thought of as a form of inductive reasoning. What separates abduction from the other forms of reasoning is an attempt to favor one conclusion above others, by attempting to falsify alternative explanations or by demonstrating the likelihood of the favored conclusion, given a set of more or less disputable assumptions.
Fallacious reasoning
Flawed reasoning in arguments is known as fallacious reasoning. Reasoning within arguments can be bad because it commits either a formal fallacy or an informal fallacy.
INFERENCE
Inference is the act or process of deriving a conclusion based solely on what one already knows. Inference is studied within several different fields. Human inference. Logic studies the laws of valid inference
The accuracy of inductive and deductive inferences
The conclusion inferred from multiple observations is made by the process of inductive reasoning. The conclusion may be correct or incorrect, and may be tested by additional observations. In contrast, the conclusion of a valid deductive inference is true if the premises are true. The conclusion is inferred using the process of deductive reasoning. A valid deductive inference is never false. This is because the validity of a deductive inference is formal. The inferred conclusion of a valid deductive inference is necessarily true if the premises it is based on are true.
Valid inferences
Inferences are either valid or invalid, but not both. Philosophical logic has attempted to define the rules of proper inference, i.e. the formal rules that, when correctly applied to true premises, lead to true conclusions. Aristotle has given one of the most famous statements of those rules in his Organon
REASONING
Reasoning is the process of looking for reasons on which to base one's beliefs or actions. In philosophy, the study of reasoning typically focuses on what makes reasoning good or bad, appropriate or inappropriate. Philosophers do this by either examining the form or structure of the reasoning within arguments, or by considering the broader methods used to reach particular goals of reasoning, such as beliefs or actions. Psychologists, in contrast, tend to study how people actually reason, and how those methods of reasoning help or hinder people.
Reasoning and forms of argument
One approach to the study of reasoning is to identify various forms of reasoning that may be used to support or justify conclusions. The main division between forms of reasoning that is made in philosophy is between deductive reasoning and inductive reasoning. Formal logic has been described as 'the science of deduction' (Jeffrey, 1991, 1). The study of inductive reasoning is generally called either 'informal logic' or 'critical thinking'.
Deductive reasoning
Deductive arguments are intended to have reasoning that is valid. Reasoning in an argument is valid if the argument's conclusion must be true when the premises (the reasons given to support that conclusion) are true. One classic example of deductive reasoning is that found in syllogisms like the following: All humans are mortal. Socrates is a human. Therefore, Socrates is mortal.
VALIDITY
Validity is a property of the reasoning in the argument, not a property of the premises in the argument or the argument as a whole. In fact, the truth or falsity of the premises and the conclusion is irrelevant to the validity of the reasoning in the argument. The following argument, with a false premise and a false conclusion, is also valid, (it has the form of reasoning known as modus ponens). If green is a colour, then grass poisons cows. Green is a colour. So, grass poisons cows.
Inductive reasoning
Inductive reasoning contrasts strongly with deductive reasoning. Even in the best, or strongest, cases of inductive reasoning, the truth of the premises does not guarantee the truth of the conlusion. Instead, the conclusion of an inductive argument follows with some degree of probability. Relatedly, the conclusion of an inductive argument contains more information than is already contained in the premises. Thus, this method of reasoning is ampliative. A classical example of inductive reasoning comes from the empiricist David Hume: The sun has risen in the east every morning up until now. So, the sun will also rise in the east tomorrow.
Abductive reasoning
However, as the conclusion in an abductive argument does not follow with certainty from its premises it is best thought of as a form of inductive reasoning. What separates abduction from the other forms of reasoning is an attempt to favor one conclusion above others, by attempting to falsify alternative explanations or by demonstrating the likelihood of the favored conclusion, given a set of more or less disputable assumptions.
Fallacious reasoning
Flawed reasoning in arguments is known as fallacious reasoning. Reasoning within arguments can be bad because it commits either a formal fallacy or an informal fallacy.
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