Code Toad is right. And it’s just common sense. New businesses and business expansions incur risk. You’re spending money with no guarantee that your risk will be rewarded. Lower taxes encourage business investment because the reduced tax burden they provide reduces the headwinds a business faces and change the risk/reward calculus. Just common sense.
And where do stock buybacks fit into this?
"The underlying logic for the TCJA was that allowing companies to keep a greater share of profits, would stimulate investments in long term growth. Instead, the dominant company response to the TCJA was stock buybacks. For the first three quarters of 2018, buybacks were $583.4 billion (up up 52.6% from 2017). In contrast, aggregate capital investment increased 8.8% over 2017, while R&D investment growth at US public companies increased 12.5% over 2017 growth." source