Suppose some claim is put before you. Suppose, for example, that somebody says

  - There is no largest prime number.

  - Ground rhino horn cures impotence.

  - Wooden flutes sound better than metal ones.

Should you agree? Well, only if the claim is true. So you need to think about whether the claim is true. That, roughly, is what we mean by evaluating a claim: making up our mind as to whether it is true or false.

Note that you will normally be evaluating a claim from your own perspective. That is, you are making up your own mind about it, given everything you know, your situation in the world, etc. You are not putting yourself in the shoes of the other person, and asking whether or not they believed it.

Truth and Confidence

In most cases – especially in complicated or important matters – you will not be able to know with absolute certainty that a claim is true, or that it is false. As a practical matter, the challenge is not to come up with a simple True/False verdict, but rather to assess how plausible the claim is, or put another way, what level of confidence you should have in it.

    To evaluate  a claim is to determine how confident you are that it

    is true (or false).

You may decide it is definitely true, highly likely, true ‘beyond reasonable doubt,’ etc.

Rational Evaluation

Very often, people decide whether a claim is true on the basis of an impulse, hunch or gut feeling. They just ‘know’ it is true in a flash, without further reflection. On other occasions, people accept claims as true on the say-so of some person in whom they place unquestioning faith, such as a parent, a religious leader, or a salesman.

Critical thinkers, by contrast, evaluate a claim carefully assessing it in the light of all relevant considerations, i.e., all relevant arguments plus any basis which may happen to apply. They attempt to determine what level of confidence a rational person should have in the claim, given the evidence available, and then accept that assessment, regardless of what they are being told, whether by another person or by their own gut feelings.

Balance of Considerations

Assuming all the relevant evidence is already at hand, evaluating a claim amounts to little more than assessing the balance of the considerations. Roughly, accept the claim to the extent that the balance of considerations supports it; reject the claim to the extent that the balance of considerations opposes it; and if the balance is more or less even, take no stand.

This makes it sound easy, but of course assessing the balance of considerations can be an involved matter, since it involves determining the strength of every individual argument and solidity of every basis bearing upon the claim, and weighing up the results.

Critical Inquiry

More typically, we are not presented with all the evidence, and may need to conduct our own investigations before making our assessment. Ideally, then, evaluating a claim involves the following major steps:

1.  Ask whether all relevant considerations have been identified and evaluated;

2.  If not, then actively seek out and evaluate all additional relevant considerations;

3.  Determine the balance of considerations;

4.  Assess your confidence in the claim, given the balance.

Needless to say, this can be quite a task. The extent to which we undertake it properly will depend on many things, such as how important the topic is, how much time we have, etc.

See also: Topics Proposition and Basis