Deductive Reasoning, Essay Example

For a Deductive Argument to be valid, the Premise itself must first be valid. No valid conclusion can be reached if the initial premise is invalid.

An example of invalid Deductive Reasoning is as follows:

1. All blue-eyed people are male
2. I have blue eyes
3. Therefore, I must be a male

This is clearly a fallacious line of reasoning. The premise that “all blue-eyed people are male” is invalid; therefore, the conclusion is invalid.

An example of valid Deductive reasoning is as follows:

1. Two brown-eyed parents cannot give birth to a child with blue eyes
2. Both of my parents have brown eyes
3. Therefore, I cannot have blue eyes

This example is valid Deductive Reasoning. It is a biological fact that two brown-eyed parents cannot give birth to blue-eyed offspring; brown eyes are caused by a “dominant gene,” while blue eyes are caused by a “recessive gene.” This means that the beginning of the Deductive Argument is based on a valid premise, and leads to a valid conclusion.