Jumping to Conclusions

When we draw a conclusion without taking the trouble to acquire all the relevant evidence, we commit the fallacy of jumping to conclusions, provided there was sufficient time to assess that extra evidence, and that the effort to get the evidence isn't prohibitive.

Example:

This car is really cheap. I'll buy it.

Hold on. Before concluding that you should buy it, you ought to have someone check its operating condition, or else you should make sure you get a guarantee about the car's being in working order. And, if you stop to think about it, there may be other factors you should consider before making the purchase. Are size or appearance or gas mileage relevant?