I used to enjoy reading some of my brother's textbooks when he was doing his Bachelor of Psychology. This one tied together a lot of ideas I had gathered intuitively through life, built upon them, and organised them into a cohesive framework. Since it is such a useful book I have taken notes on it and included them here, for personal reference.

The first 8 chapters cover the foundations of logic, argumentation, psychological biases and fallacies, using plenty of real-world case studies. The book then introduces the SEARCH formula - a critical thinking framework for analysing any kind of claim - ranging from mundane to paranormal:

1. State the claim as specifically as possible without using weasel words. It is important to avoid these, since they make arguments appear specific or meaningful, while actually being ambiguous and allowing the person proposing the claim to later deny any specific meaning when the claim is challenged.
2. Evaluate the claim using reason and/or evidence: Did it actually happen? If not then consider why. Was the claim a sound argument? A sound argument involves premises and a conclusion that must follow solely from the premises. Premises must be known facts.
3. Consider Alternative hypotheses. Humans have a lot of inbuilt biases. For example, our brains are good at pattern recognition, but we often latch on to a pattern that seems correct without ever testing it (doing this is known as confirmation bias). We have many other kinds of biases inherent in our brains too, however this does not mean we are doomed to ignorance. There are philosophical tools we can use to overcome our biases. The best way to avoid confirmation bias is to search for disconfirming evidence. Having an open mind means being willing to consider any possibility and changing your view in light of good reasons.
4. Rate, according to the Criteria of adequacy, each Hypothesis:
   • Testability - can the hypothesis be tested? Is there any possible way to determine whether the hypothesis is true or false? If a claim is not testable then it does not mean its false - it means it is worthless. Hypotheses that are testable are preferable to those that are not.
   • Fruitfulness - Does the hypothesis yield observable surprising predictions that explain new phenomena? Those that do are preferable to those that do not.
   • Scope - How many different phenomena can the hypothesis explain? The more the better.
   • Simplicity - is the hypothesis the simplest explanation for the phenomenon? Generally, the simplest hypothesis that explains the phenomenon is the best. For a hypothesis to be the simplest then it must make the fewest assumptions.
   • Conservatism - Is the hypothesis consistent with well founded beliefs? I.e. is it consistent with empirical evidence and with knowledge we have from verifiable scientific experiments? If the hypothesis conflicts with a highly confirmed theory then the hypothesis must be regarded as improbable until good evidence shows that the hypothesis is right and the theory is wrong.

These 4 steps are a general guide for assessing any claim. You might not always be able to discard a claim, or to tell if a claim is definitely true, but you can always weigh it against other claims and see which one stacks up best.