Why do scientists test null hypotheses instead of hypotheses?

Question

Why do scientists test null hypotheses instead of hypotheses?

Answer 1

the null hypothesis is to determine STATISTICAL significance which is then used to prove or disprove the 'overall' hypothesis

Answer 2

Scientists test null hypotheses because science advances by disproving hypotheses, not proving them.  We can never proven something to be 100% fact 100% of the time.  We can, however, show certain things never happen.  

Example:

Hypothesis:  Plants can survive without water (or Plants need water to survive).  The basic hypothesis is an educated guess.  But then we break it down into the most simple components when we test it experimentally.

Null Hypothesis: Plants given water will have equal survival rate as plants deprived of water.

Alternative Hypothesis: Plants given water will differ in survival rate than plants deprived of water.

After sufficient experimentation, we will probably find that plants without water will die. Therefore we reject our null hypothesis (and by default we accept our alternative hypothesis).  The next step would be to test other factors that might affect plant survival (sunlight, nutrients, etc).  

If we were to accept our alternate hypothesis, it may lead us to believe that water is the only thing plants need in order to survive.  By accepting our null hypothesis we realize that water is important to plant survival, but we do not rule anything else out.  So basically, by testing a null hypothesis scientists break down questions into the most simple format.  This insures scientists do not come to conclusions without proper experimental evidence.  

Answer 3

I assume you're not just joking here..

I don't think the issue is so much one of testing the null hypothesis.  Rather, if you hypothesize a mechanism to explain an observed phenomenon, an alternative hypothesis is just that the phenomenon happened by chance (the null hypothesis).  In most cases, in order for a hypothesis to be proven, the null hypothesis has to be disproven.  In general, this is done statistically.  For example, in most biomedical research, if there's less than a 2% chance of the observed finding to have occurred by chance, the null hypothesis is rejected.

Answer 4

i don't understand that question... wat d'ya mean??? an hypothesis is an educated quess based on observations.... wat u mean by null hypothesis?