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Premises and Conclusions

Arguments consist of two main components: premises and conclusions.

Premises​

Premises are statements that are presented as reasons or evidence to support a conclusion. They are the starting points of an argument, which are assumed to be true or supported by evidence.

Properties of premises:

  • They can be explicit (expressly formulated) or implicit (unspoken but presupposed)
  • They should be relevant to the conclusion
  • Their truth or plausibility influences the strength of the argument

Examples of premises:

  • "All humans are mortal." (Premise 1)
  • "Socrates is a human." (Premise 2)

Conclusions​

The conclusion is the statement that is derived from the premises and that the argument is intended to support. It is what the arguer wants to establish as true.

Properties of conclusions:

  • They follow logically from the premises (in a valid argument)
  • They are often introduced by indicators like "therefore", "consequently", "thus", or "hence"
  • They can serve as premises in further arguments

Example of a conclusion:

  • "Therefore, Socrates is mortal."

Identifying Premises and Conclusions​

To identify premises and conclusions in an argument, the following strategies can be helpful:

  1. Look for conclusion indicators:

    • "Therefore", "consequently", "thus", "hence", "it follows that", "this shows", "this proves"
    • These words often introduce the conclusion

  2. Look for premise indicators:

    • "Because", "since", "for", "due to", "given that", "the reasons are"
    • These words often introduce premises

  3. Ask "Why?":

    • The conclusion answers the question "What is being claimed?"
    • The premises answer the question "Why should one believe this?"

  4. Reconstruct the argument:

    • Identify the main statement that needs to be justified (conclusion)
    • Identify the statements that are presented as justification (premises)

Example of Argument Analysis​

Let's consider the following argument:

"Since all planets in our solar system orbit the sun and Pluto orbits the sun, Pluto must be a planet in our solar system."

Analysis:

  • Premise 1: "All planets in our solar system orbit the sun."
  • Premise 2: "Pluto orbits the sun."
  • Conclusion: "Pluto is a planet in our solar system."

This argument contains a logical error, as it confuses a necessary condition (orbiting the sun) with a sufficient condition. Not everything that orbits the sun is automatically a planet (e.g., asteroids, comets).