First from last month, Alex B. Berezow in the LA Times:
Psychology isn't science.
Why can we definitively say that? Because psychology often does not meet the five basic requirements for a field to be considered scientifically rigorous: clearly defined terminology, quantifiability, highly controlled experimental conditions, reproducibility and, finally, predictability and testability.
Happiness research is a great example of why psychology isn't science. How exactly should “happiness” be defined? The meaning of that word differs from person to person and especially between cultures. What makes Americans happy doesn't necessarily make Chinese people happy. How does one measure happiness? Psychologists can't use a ruler or a microscope, so they invent an arbitrary scale. Today, personally, I'm feeling about a 3.7 out of 5. How about you?
The failure to meet the first two requirements of scientific rigor (clear terminology and quantifiability) makes it almost impossible for happiness research to meet the other three.
Next, Ashutosh Jogalekar responds in the Scientific American blog The Curious Wavefunction:
At the heart of Berezow’s argument is psychology’s lack of quantifiability and dearth of accurate terminology. He points out research in fields like happiness where definitions are neither rigid nor objective and data is not quantifiable.
Happiness research is a great example of why psychology isn’t science. How exactly should “happiness” be defined? The meaning of that word differs from person to person and especially between cultures. What makes Americans happy doesn’t necessarily make Chinese people happy. How does one measure happiness? Psychologists can’t use a ruler or a microscope, so they invent an arbitrary scale. Today, personally, I’m feeling about a 3.7 out of 5. How about you?
This is absolutely true. But you know what other fields suffer from a lack of accurate definitions? My own fields, chemistry and drug discovery. For instance there has been a longstanding debate in our field about how you define a “druglike” molecule, that is, a chemical compound most likely to function as a drug. The number of definitions of “druglike” that have sprung up over the years are sufficient to fill a phonebook. The debate will probably continue for a long time. And yet nobody will deny that work on druglike compounds is a science; the fact is that chemists use guidelines for making druglike molecules all the time and they work. In fact why talk about druglike compounds when all of chemistry is sometimes regarded as insufficiently scientific and rigorous by physicists? There are several concepts in chemistry – aromaticity, hydrophobic effects, polarizability, chemical diversity – which succumb to multiple definitions and are not strictly quantifiable. Yet nobody (except perhaps certain physicists) denies that chemistry is a science.