Syllogism, heuristic and algorithm

First of all I  want to talk about syllogism. It  is a kind of logical argument in which one proposition (the conclusion) is inferred from two or more others (the premises) of a specific form.There are two basic premises: Major premise and minor premise. To understand better I want to give examples:

Major premise: "All birds are animals"

Minor premise: "All parrots are birds"

Conclusion: "All parrots are animals".

Major premise: People have fun in Disnaland.

Minor premise: John is in Disnaland

Conclusion: John has fun

Major premise: All men are animals

Minor premise: Some animals are aggressive

Conclusion: Some men are aggressive

Sadly, the logic and truth that we assume is not always right.for example.

Major premise: All men are animals

Minor premise: Some animals are female

Conclusion: Some men are female

Now the conclusion appears to be ridiculous and false - yet the reasoning is exactly the same as in the first example. The first example thus has a false conclusion. The animals who are aggressive are not necessarily men.

Algorithm is a rule that, if applied appropriately, guarantees a solution to a problem. We can use an algorithm even if we cannot understand why it works. For example, formulas in  mathematics and physics. It helps as to do exersices, but it much more difficult to find formula to solve our own problems, but we‘r able to use heuristics to help us. A heuristic is a cognitive shortcut that may lead to a solution. I want to indroduce you with two types of heuristic. Firstly, representativeness heuristic. It is a rule we apply when we judge people by the degree to which they represent a certain category or group of people.

Example No.1.  If I meet three people from a company and they are all aggressive, I will assume that the company has an aggressive culture and that most other people from that firm will also be aggressive.

Example No.2. If I meet someone with a laid back attitude and long hair, I might assume they are Californian, whereas someone who is very polite but rigid may be assumed to be English.

The availability heuristic involves judging the probability of an event on the basis of how

easily the event can be recalled from memory.

Example No.1 : A person argues that cigarette smoking is not unhealthy because his grandfather smoked three packs of cigarettes a day and lived to be 100. The grandfather's health could simply be an unusual case that does not speak to the health of smokers in general.

Example No.2. A lot of  people‘re using iPods” so they think it’s very popular, so more people buy it, more popular it becomes.

In conclusion, I want to say that people do the same things like in these examples all the  time. It seems difficult to understand everything from deffinition, but it shows that we faceing with making desision evryday.


References: Robert S. Feldman  Essentials of Understanding Psychology, eight edition, higher education, 2008, p. 243.
http://www.wikihow.com/Understand-Syllogisms
http://en.wikipedia.org/wiki/Syllogism
http://en.wikipedia.org/wiki/Heuristic